[2026 Edition] Top 3 Constipation Medications Frequently Prescribed by Doctors | Comparing Effects, Side Effects, and Usage
[2026 Edition] Top 3 Constipation Medications Frequently Prescribed by Doctors | Comparing Effects, Side Effects, and Usage
"Since all constipation medications are for passing stool, aren't they all basically the same in how they work?"
Many people may think this way. However, constipation medications prescribed at hospitals work on the intestines in different ways depending on the drug.
Some drugs draw water into the intestines to soften the stool, some cause water to be secreted from the intestinal surface, and others utilize the action of bile acids to help with intestinal water content and movement.
Therefore, the number one constipation medication frequently prescribed by doctors is not necessarily the most recommended medication for everyone.
When choosing a constipation medication, it is necessary to consider not just "how many days it has been since the last bowel movement," but also the following information comprehensively:
Whether the stool is hard or soft
Whether you have the urge to defecate but it is difficult to pass
Whether you feel like you haven't fully emptied your bowels after defecation
Whether you have abdominal pain or bloating
Whether you experience diarrhea or nausea when taking the medication
Whether your kidney function is impaired
Whether you are pregnant or there is a possibility of pregnancy
Whether you are taking any other medications
Therefore, in this article, based on the 2026 doctor survey provided, we will introduce the top 3 medications frequently prescribed for chronic constipation.
In addition to the ranking, we will explain in an easy-to-understand manner what each constipation medication does in the intestines, what symptoms to watch out for as side effects, and what you should consult with your doctor or pharmacist about.
Note that the rankings introduced in this article are not in order of "highest effectiveness" or "highest safety." Furthermore, this does not recommend the use of any specific constipation medication. Do not increase, decrease, stop, or change the dosage of prescribed medication on your own judgment, and if you have any concerning symptoms, please consult your doctor or pharmacist.
Top 3 Medications for Chronic Constipation Frequently Prescribed by Doctors in 2026
In the 2026 survey, the top 3 medications frequently prescribed by doctors for chronic constipation are as follows:
1st Place: Magnesium Oxide
2nd Place: Elobixibat
3rd Place: Lubiprostone
Although all three types of medication are used for constipation, they do not act on the same areas or through the same mechanisms.
Magnesium oxide, ranked first, is a type of medication called an osmotic laxative. Rather than directly and strongly stimulating the intestines, it draws water into the intestines to soften hard stool, preparing it for easier bowel movements.
Goofice, ranked second, has the generic name elobixibat hydrate. It inhibits the mechanism by which bile acids are reabsorbed in the final part of the small intestine, increasing the amount of bile acid that reaches the large intestine. As a result, water secretion and intestinal movement within the large intestine are promoted. Typically, 10 mg of elobixibat is taken once daily before meals, and the dosage is adjusted according to symptoms.
Amitiza, ranked third, has the generic name lubiprostone. It acts on chloride channels in the epithelium of the small intestine to promote water secretion into the intestinal tract. Typically, 24 μg of lubiprostone is taken twice daily, after breakfast and dinner, and the dosage may be reduced depending on symptoms.
This ranking is not a list of 'recommendations'.
The most important point to understand when looking at this ranking is that the medication prescribed most frequently is not necessarily the best medication for an individual.
When doctors prescribe medication, they check various conditions, including not only the effectiveness of the drug but also the patient's age, stool consistency, underlying diseases, kidney function, other medications being taken, and the effectiveness and side effects of constipation medications used in the past.
Furthermore, prescription frequency can be influenced by factors such as ease of dosage adjustment, the doctor's familiarity with the drug, the price of the medication, and the frequency of administration.
For example, although magnesium oxide is ranked first, it is not a medication that everyone can continue taking unconditionally. The package insert for magnesium oxide lists hypermagnesemia as a serious side effect.
Caution is especially required for those with reduced kidney function, the elderly, and those taking it for long periods. Furthermore, serious hypermagnesemia has been reported even in individuals with normal kidney function or those taking less than the standard dose. Regular monitoring of serum magnesium levels is required for long-term use or administration to the elderly.
On the other hand, Amitiza and Goofice are medications that improve constipation through mechanisms different from that of magnesium oxide.
When magnesium oxide does not provide sufficient results in adjusting stool consistency, or when it is necessary to consider not only stool consistency but also intestinal movement, medications with different actions may be considered.
However, it is not possible to simply decide based on symptoms alone, such as 'this medication because the stool is hard' or 'this medication because there is no urge to defecate.' A doctor's judgment is necessary, including consideration of side effects like abdominal pain or diarrhea, and the possibility of underlying diseases.
Even with the same constipation medication, the way they affect the intestines differs.
The differences between the three types can be summarized simply as follows.
Magnesium oxide draws water into the intestines.
Amitiza acts on the surface of the intestines to make it easier for water to be released into the intestinal tract.
Goofice promotes not only water secretion but also intestinal movement by making it easier for bile acids to reach the large intestine.
While all are medications that ultimately aim for a state that facilitates bowel movements, the mechanisms to reach that point differ. Therefore, the symptoms likely to appear as side effects, the appropriate timing for administration, and the people who need to be especially careful also differ.
When comparing constipation medications, it is important not just to look at the ranking order, but to check the following four points.
What is the mechanism of action for this medication?
What are the potential side effects?
When should it be taken, such as before or after meals?
Are there any precautions regarding my underlying conditions or other medications I am taking?
From the next chapter onwards, we will explain in detail the effects, side effects, usage, and points to discuss for the 3rd place Amitiza, 2nd place Goofice, and 1st place Magnesium Oxide, in that order.
3rd Place: Amitiza is a laxative that promotes water secretion into the intestines
In the 2026 doctor survey, the 3rd place medication was the generic name 'lubiprostone,' brand name 'Amitiza'.
Amitiza is a medication that helps soften hard stools and assists in bowel movements by making it easier for water to be released into the intestines.
Some people may have the image that 'laxatives are drugs that force stool out by stimulating the intestines.' However, Amitiza is not the type that directly stimulates the intestines to cause strong movements. It acts on the surface of the small intestine to increase the water content within the intestinal tract, thereby preparing the stool to move more easily through the intestines.
However, being in 3rd place does not mean it is less effective. This ranking is simply the result of a survey asking doctors which medications they prescribe most frequently. Depending on the patient's stool condition, underlying diseases, the effects of previously used medications, and side effects, Amitiza may be considered as a candidate for prescription.
Amitiza acts on chloride channels in the small intestine
Technically speaking, Amitiza is a medication that activates 'ClC-2 chloride channels' located on the epithelial cells of the small intestine.
Chloride channels are pathways on the surface of the intestine involved in the movement of chloride ions. When Amitiza acts on these pathways, water secretion into the intestinal tract is promoted.
When the water content in the intestines increases, hard stool becomes softer and moves more easily through the intestinal tract. As a result, bowel movements are promoted. The package insert published by the PMDA also indicates that it has the effect of promoting water secretion into the intestinal tract to soften stool and enhance transport within the intestinal tract.
In simple terms, Amitiza is not a 'drug that forces stool out,' but a 'drug that adjusts the water environment in the intestines so that stool can move easily'.
Therefore, it is sometimes used for constipation symptoms such as hard stool that is difficult to pass or the need to strain strongly during bowel movements. However, since the causes and symptoms of constipation vary from person to person, it does not necessarily mean that 'if the stool is hard, Amitiza will always be a good fit'.
The main side effects of Amitiza are diarrhea, nausea, and abdominal pain
When taking Amitiza, the water content in the intestinal tract increases, which may cause the stool to become too soft, leading to diarrhea. Nausea, abdominal pain, abdominal discomfort, abdominal bloating, and vomiting may also occur.
The frequency of major side effects listed in the package insert is 30% for diarrhea, 23% for nausea, and 6% for abdominal pain. While these do not occur in everyone, nausea and diarrhea are symptoms to be particularly aware of while taking the medication.
If diarrhea persists, if you cannot eat due to nausea, or if abdominal pain interferes with your daily life, do not endure it and continue taking the same dose; instead, consult the prescribing doctor or pharmacist.
Amitiza comes in 24μg and 12μg formulations, and doctors may consider reducing the dose depending on symptoms and side effects. However, changing the frequency or dosage on your own can lead to insufficient effectiveness or make it difficult to evaluate your symptoms. It is important not to reduce, pause, or stop the medication on your own judgment, but to follow your doctor's instructions.
Although rare, anaphylaxis is also listed as a serious side effect. If you experience clear abnormalities such as difficulty breathing or generalized hives after taking the medication, you should consult a medical institution immediately.
Amitiza is usually taken after breakfast and dinner.
For adults, Amitiza is usually taken as 24μg of lubiprostone twice a day, after breakfast and dinner. Depending on the symptoms, the dosage may be reduced at the doctor's discretion.
The important thing is to follow the prescribed instruction to take it after meals.
Patient medication materials explain that taking it on an empty stomach makes nausea more likely, while taking it after a meal makes nausea less likely. If you skip breakfast, do not decide on your own to take it on an empty stomach; instead, check with your doctor or pharmacist on how to handle such situations.
If you forget to take a dose, do not take two doses at once. Since the appropriate action may change depending on the time until your next scheduled dose, please check the instructions you received when the prescription was filled or the information on the medication bag.
Also, Amitiza is not a medication that should be taken aimlessly in the same amount even after symptoms have improved. The package insert indicates that if continuous symptom improvement is achieved or if side effects occur, reducing, pausing, or stopping the medication should be considered based on the symptoms.
People who are pregnant or may be pregnant cannot take this medication.
As a point of caution for Amitiza, the restrictions regarding pregnancy are particularly important.
Amitiza is contraindicated for pregnant women or women who may be pregnant. This is not just a medication to be used with caution; it falls under the contraindications in the package insert.
Because animal studies have reported fetal transfer and fetal loss, when prescribing to women who may become pregnant, it must be confirmed that they are not pregnant, and contraception must be used while taking the medication. If you discover you are pregnant or if there is a possibility of pregnancy while taking the medication, do not wait until your next appointment; contact your prescribing doctor immediately.
Use while breastfeeding is not treated the same as during pregnancy. A doctor will decide whether to continue or stop breastfeeding by considering the therapeutic necessity and the benefits of breastfeeding. Do not start taking the medication without informing your doctor that you are breastfeeding.
It also cannot be used by people who have confirmed intestinal obstruction due to tumors or hernias, or by those suspected of having intestinal obstruction. If you experience severe abdominal pain or vomiting that is different from your usual constipation, it is important to consult a medical institution rather than waiting to see if constipation medication helps.
Reasons why doctors prescribe Amitiza
In the survey presented, the following opinions were cited as reasons why doctors prescribe Amitiza:
There are 24μg and 12μg formulations, making it easy to adjust the dosage.
It is used for patients who do not get sufficient effects from magnesium oxide.
It is felt to be easy to use long-term.
However, these are opinions based on the prescribing experience and evaluations of the doctors who responded to the survey. This does not mean that Amitiza is easy for all patients to use or that no problems will occur if taken for a long period.
When actually using the medication, it is necessary to check not only whether constipation symptoms are improving, but also whether side effects such as diarrhea, nausea, or abdominal pain are occurring. A doctor will determine the dosage and whether to continue treatment while balancing the benefits and side effects.
5 points to discuss while taking Amitiza
If you are taking Amitiza, communicating the following items to your doctor or pharmacist will make it easier to review your treatment plan.
Whether you experience nausea, diarrhea, or abdominal pain after taking it
How your bowel movement frequency and stool consistency have changed
Whether there are many days when you cannot eat breakfast or dinner
Whether you are pregnant or there is a possibility of pregnancy
Whether you have been told that you have reduced kidney or liver function
Do not think, "I'm not sure if it's working" or "I have nausea, but it's tolerable so I don't need to mention it"; be sure to communicate any changes you are concerned about specifically.
Amitiza is a constipation medication that softens stool by secreting water into the intestinal tract. On the other hand, an important point to note is that diarrhea and nausea are relatively common, and it cannot be used by women who are pregnant or may be pregnant.
It is important to check with your doctor or pharmacist whether the prescription is right for you, including your stool condition, side effects, underlying medical conditions, and impact on your daily life, rather than focusing on the ranking of the medication.
2nd Place: Goofice is a constipation medication that uses bile acids to assist intestinal moisture and movement
The medication that ranked 2nd in the 2026 doctor survey is the generic name "elobixibat hydrate," brand name "Goofice."
To explain Goofice simply, it is a constipation medication that utilizes the function of bile acids naturally present in the body to increase the amount of water in the large intestine and promote intestinal movement.
Amitiza and magnesium oxide are also medications that increase the amount of water in the intestines to create a state where it is easier to have a bowel movement, but their methods are not the same. Goofice has a unique mechanism of reducing the amount of bile acid reabsorbed in the small intestine, thereby increasing the amount of bile acid that reaches the large intestine.
As a result, the secretion of water and electrolytes into the large intestine is promoted, and the movement of the digestive tract is also activated. In other words, Goofice is a medication that not only softens stool but also relates to the intestinal movement that leads to bowel movements.
However, being in 2nd place does not mean it is less effective than magnesium oxide or superior to Amitiza. This ranking is based on the medications frequently prescribed by the doctors who responded to the survey. Which medication is actually suitable depends on stool consistency, frequency of bowel movements, presence of abdominal pain, underlying conditions, and concomitant medications.
Goofice inhibits IBAT, which reabsorbs bile acids
Bile acid is a substance produced in the liver. It plays a role mainly in helping the digestion and absorption of fats and is secreted into the small intestine in accordance with meals.
Normally, most of the secreted bile acid is reabsorbed in the terminal ileum, located at the end of the small intestine, and used again in the body. The "IBAT," or bile acid transporter, is involved in this reabsorption of bile acid.
Goofice inhibits the function of this IBAT. As a result, bile acids that would normally be reabsorbed in the small intestine are more likely to reach the large intestine. The increase in bile acids flowing into the large intestine promotes the secretion of water and electrolytes, stimulates gastrointestinal motility, and creates a state that facilitates bowel movements.
To put it simply, Goofice is a medication that delivers bile acids to the large intestine and utilizes their power for bowel movements.
While magnesium oxide primarily draws water into the intestines to soften stool, Goofice works through bile acids to affect both water secretion and intestinal motility. This difference in action serves as a criterion when selecting a constipation medication.
Goofice is typically taken once daily before meals.
For adults, Goofice is typically taken as 10 mg of elobixibat once daily before a meal. The doctor may adjust the dosage according to symptoms, but the maximum daily dose is 15 mg.
Since Goofice tablets are 5 mg each, actual prescriptions may be adjusted within the range of 5 mg, 10 mg, and 15 mg. However, because the dosage is determined by the doctor based on bowel movement status, abdominal pain, diarrhea, etc., you must not increase or decrease the number of tablets on your own.
What is particularly important when taking Goofice is the timing: 'before a meal'.
When you eat, bile acids are released into the duodenum. Goofice is a medication that inhibits the reabsorption of these released bile acids at the terminal ileum. Therefore, it is considered important to take it before bile acids are released by a meal in order for it to work efficiently.
In domestic clinical trials, it was mainly administered before breakfast, but the approved usage is 'before a meal,' not 'before breakfast.' For those who do not eat breakfast, it may be taken before lunch or dinner depending on the prescribing doctor's instructions.
Taking the medication after meals, before bedtime, between meals, or as needed (PRN) is not an approved method of administration. If it is difficult to take it before a meal due to your lifestyle rhythm, do not change the timing on your own; consult your doctor or pharmacist.
Do not take two doses at once if you forget to take it.
If you forget to take Goofice before a meal, you must not take two doses at once.
Information for medical professionals from the pharmaceutical company indicates that if you forget to take it before a meal, it should be taken before the next meal. However, it may be better to confirm the appropriate response based on your usual dosing time, the interval until the next meal, and instructions received from your doctor.
In particular, if someone instructed to take it before dinner forgets to do so, the guidance is to wait until the next meal rather than taking it before bedtime on the same day.
If you are unsure what to do when you realize you have forgotten to take your medication, check the medicine bag or patient materials, or contact the medical institution or pharmacy that prescribed it.
If you think, 'I want to make up for the missed dose,' and take two doses at once, you may experience severe abdominal pain or diarrhea. As a general rule for all prescription medications, not just Goofice, do not take a double dose on your own judgment.
The main side effects of Goofice are abdominal pain and diarrhea.
The side effects to be particularly aware of with Goofice are abdominal pain and diarrhea.
The electronic package insert states that abdominal pain occurs in 23.2% of cases and diarrhea in 14.4%. Other symptoms that may occur include lower abdominal pain, abdominal bloating, nausea, upper abdominal pain, abdominal discomfort, loose stools, and urgency of defecation.
Goofice is a medication that promotes water secretion and gastrointestinal motility in the large intestine. Therefore, if the medication's effects are strong, your stool may become too soft, you may experience sudden urges to defecate, or you may have stomach pain.
Even if symptoms are mild abdominal pain or loose stools, if they persist daily or affect your work or outings, please inform your doctor or pharmacist.
Consultation is especially necessary as soon as possible in the following situations:
Severe abdominal pain that interferes with daily life
Persistent watery diarrhea
Sudden urge to defecate that prevents you from going out
Inability to consume enough food or fluids due to diarrhea
Accompanied by nausea or vomiting
Symptoms gradually worsening since starting the medication
The electronic package insert states that if abdominal pain or diarrhea occurs, consideration should be given to reducing the dose, pausing, or discontinuing the medication depending on the symptoms. It also indicates that administration should not be continued indefinitely without confirming the necessity.
Just because there are side effects does not necessarily mean you should stop taking the medication immediately. Since symptoms may subside by reducing the dosage, it is important to convey the specific situation to your prescribing doctor and follow their judgment.
Do not just monitor the situation with constipation medication alone if you have severe abdominal pain or vomiting.
Goofice cannot be used by people who have confirmed intestinal obstruction due to tumors or hernias, or by those suspected of having intestinal obstruction. This is because it may worsen the obstruction.
If you experience severe abdominal pain different from your usual constipation, significant abdominal distension, repeated vomiting, or symptoms where neither gas nor stool is passed, do not take additional Goofice to try to defecate; instead, consult a medical institution.
Furthermore, the indication for Goofice is "chronic constipation excluding constipation caused by organic diseases." If it has become difficult to pass stool due to diseases of the intestine itself, such as colorectal cancer or intestinal obstruction, it is necessary to address the underlying disease.
If you notice changes such as long-standing constipation suddenly worsening, stools becoming thinner, blood in the stool, or weight loss, do not just adjust your constipation medication; be sure to mention these during your consultation.
Inform your doctor in advance if you are pregnant, elderly, or have severe liver impairment.
Goofice is not a drug contraindicated for pregnant women like Amitiza. However, it is intended to be used in pregnant women or women who may be pregnant only if the doctor determines that the benefits of treatment outweigh the risks.
If you are breastfeeding, it is also necessary to consider whether to continue or discontinue breastfeeding, taking into account the necessity of treatment and the benefits of breastfeeding. If you are pregnant, may be pregnant, or are breastfeeding, please be sure to inform your doctor before the prescription is issued.
Additionally, since elderly patients often have reduced physiological functions, caution such as dose reduction is considered necessary.
In people with severe liver dysfunction who have biliary obstruction or reduced bile acid secretion, it is possible that the full effects of Goofice may not be obtained. This is because Goofice is a drug that utilizes bile acids, so if there is little bile acid secreted into the small intestine to begin with, the mechanism of the drug becomes difficult to utilize.
There are some drug interactions to be aware of with Goofice
When getting a prescription for Goofice, be sure to inform your doctor or pharmacist about all medications you are currently taking, including those other than constipation medicine.
The electronic package insert states that caution is required when using it in combination with ursodeoxycholic acid (a bile acid preparation), antacids containing aluminum, or bile acid sequestrants such as cholestyramine or colestimide.
Additionally, the effects of digoxin and dabigatran may be intensified, while the effects of midazolam may be weakened.
If you are using over-the-counter stomach medicine or other non-prescription drugs, do not assume that you do not need to mention them because they are not prescription drugs; instead, record them in your medication notebook or check with a pharmacist while having the product name available.
While it may sometimes be prescribed alongside other constipation medications, domestic clinical trials at the time of approval were generally conducted with Goofice alone, and there is not sufficient data on the efficacy and safety of using it in combination with other constipation treatments. Avoid adding concomitant medications on your own judgment.
Reasons why doctors prescribe Goofice
In the survey presented, the following opinions were cited as reasons why doctors prescribe Goofice:
It is easy to use with once-daily dosing
It is easy to adjust the dosage within the 5mg, 10mg, and 15mg range
It not only softens stool but also relates to intestinal movement
It has a different mechanism of action than magnesium oxide and others
The once-daily dosing frequency can be a factor that makes it easier to continue treatment for people who find it difficult to take medication twice a day, in the morning and evening.
Furthermore, the ability to consider reducing the dose if abdominal pain or diarrhea is severe, and increasing the dose if the effect is insufficient and there are no issues with side effects, is also considered one of the reasons why doctors prescribe it.
However, these are opinions based on the prescribing experience of the doctors who responded to the survey. It does not mean that it is easy for everyone to use because it is once daily, or that side effects can be prevented because it can be adjusted in three stages.
It is necessary to evaluate not only the low frequency of dosing but also whether your lifestyle rhythm allows for taking it before meals, and whether abdominal pain or diarrhea is affecting your daily life.
Points to discuss while taking Goofice
If you are taking Goofice, it will be easier to adjust your treatment if you communicate the following information during consultations or medication guidance:
How long after taking it do you experience bowel movements or abdominal pain?
How many times a week do you have diarrhea or loose stools?
Do you experience sudden urges to defecate that affect your outings or work?
Are you able to consistently take the medication before meals?
Has your constipation improved with the current dosage?
Are you taking any other constipation medications or over-the-counter stomach medicines concurrently?
Do you have any concerns regarding pregnancy, breastfeeding, or liver dysfunction?
There is no need to endure it by thinking, 'I have abdominal pain, but since I can pass stool, it can't be helped.' Conversely, it is also dangerous to increase the dosage on your own, thinking, 'It's not working because I don't have a bowel movement right away.'
Be sure to communicate not only the frequency of bowel movements but also specific details such as stool consistency, abdominal pain, diarrhea, the timing of the urge to defecate, and any sensation of incomplete evacuation, so that your doctor can help you balance the benefits and side effects.
Goofice is a constipation medication that suppresses the reabsorption of bile acids and increases the amount of bile acids reaching the large intestine, thereby promoting water secretion and intestinal movement.
While it can usually be taken once a day before meals and allows for dosage adjustments based on symptoms, it is characterized by a relatively higher likelihood of causing abdominal pain and diarrhea.
It is important not to judge solely by the ranking, but to consult with your doctor or pharmacist, taking into account whether you can take it before meals, whether sudden urges or abdominal pain are affecting your daily life, and whether there are any issues with concurrent medications.
No. 1: Magnesium oxide is a medication that draws water into the intestines to soften stool.
The top-ranked medication in the 2026 doctor survey is 'magnesium oxide.' It is prescribed as a medical drug under brand names such as 'Magmitt,' and there are also over-the-counter constipation medications containing the same ingredient.
To explain magnesium oxide simply, it is a medication that draws water into the intestines to soften hard stool, preparing it for easier evacuation.
Some constipation medications are 'stimulant laxatives' that stimulate the nerves of the intestines to strengthen peristalsis. Magnesium oxide, on the other hand, is not a drug that directly and strongly stimulates the intestines to push out stool. It is classified as an 'osmotic laxative' that adjusts stool consistency by increasing the water content in the intestines.
Therefore, it may be prescribed in cases where stool is hard, there is a need to strain strongly during bowel movements, or the anus is painful due to hard stool.
However, just because it is ranked first does not mean it is the optimal and safely sustainable constipation medication for everyone. With magnesium oxide, it is necessary to consider factors including kidney function, age, duration of use, dosage, and interactions with other medications.
Magnesium oxide is classified as an 'osmotic laxative'.
After reacting with stomach acid and other substances, magnesium oxide increases osmotic pressure in the intestines, creating a state where water is easily retained within the intestinal tract.
The term 'osmotic pressure' might sound difficult, but in the context of constipation treatment, it is easy to understand as 'a mechanism that draws water into the intestines to soften hard stool.'
When stool contains water, hard and dry stool becomes softer and moves more easily through the intestines. The increase in stool volume can also stimulate the intestines, leading to a bowel movement.
Magnesium oxide is used not only for constipation but also as an antacid to neutralize stomach acid. Regarding adult dosage for constipation, the electronic package insert typically states that it should be taken in three divided doses before or after meals, or once before bedtime. However, since the actual dosage is adjusted based on age and symptoms, it is essential to follow the prescribed amount and timing.
Since tablets come in various strengths, the total amount differs depending on the content per tablet, even if the number of tablets is the same. You should not compare the number of tablets with others or adjust the dosage based on your own judgment by referring to previous prescriptions.
Being ranked first does not mean it is suitable for everyone
The reasons why magnesium oxide is frequently prescribed include the ease of adjusting the dose according to stool consistency, its long history of use, and its relatively low cost.
In the doctor survey presented, reasons for prescribing included opinions such as "it is easy to adjust the dose," "it is relatively inexpensive," and "it gives the impression of causing less abdominal pain."
However, these are opinions based on the prescribing experience and impressions of the doctors who responded to the survey. It does not mean that "magnesium oxide has no side effects" or that "it is always safe to take for a long period."
In addition to the possibility of diarrhea, hypermagnesemia is listed as a serious side effect of magnesium oxide. While taking it, it is important to check not only if your constipation has improved but also if your stool has become too soft and if there are any changes in your physical condition.
What is hypermagnesemia, which requires special attention?
Hypermagnesemia is a condition in which the concentration of magnesium in the blood becomes too high.
A portion of magnesium oxide is absorbed into the body from the digestive tract. The absorbed magnesium is mainly excreted from the body through the kidneys, but if kidney function is impaired, it may accumulate in the body, causing blood concentrations to rise.
In the early stages of hypermagnesemia, symptoms such as nausea, vomiting, dry mouth, low blood pressure, slow pulse, skin redness, muscle weakness, and strong drowsiness may appear. If it becomes more severe, it can progress to conditions such as weakened breathing, loss of consciousness, and arrhythmia, which may potentially lead to cardiac arrest.
If you experience any of the following symptoms while taking magnesium oxide, you should be cautious:
Persistent nausea or vomiting
Stronger drowsiness than usual
Difficulty exerting strength throughout the body
Feeling mentally foggy or confused
Feeling that your pulse is slow
Blood pressure dropping to the point where you cannot stand
Feeling short of breath or having weak breathing
The electronic package insert instructs patients to stop taking the medication and seek medical attention immediately if symptoms such as vomiting, bradycardia, muscle weakness, or drowsiness occur. Do not judge these symptoms as mere fatigue or constipation-related discomfort; inform your medical institution about the medication you are taking.
Hypermagnesemia can occur even if kidney function is normal
It is not appropriate to assume that "as long as your kidneys are healthy, there is no problem with continuing to take magnesium oxide."
People with impaired kidney function need to be especially careful, as they cannot excrete magnesium sufficiently and are more likely to develop hypermagnesemia.
However, the electronic package insert warns that for patients with constipation, there have been reports of serious outcomes even when kidney function is normal or when the medication is taken at or below the usual dosage. Therefore, it is required to limit use to the minimum necessary and, if taking it for a long period, to take measures such as periodically measuring serum magnesium levels.
You should be especially careful if you are one of the following:
A person who has been told they have reduced kidney function
An elderly person
A person who has been taking magnesium oxide for a long time
A person who is taking magnesium from both prescription and over-the-counter medications
A person who has problems with heart function
A person who has persistent diarrhea or dehydration
In elderly patients, the individual may not be able to properly report abnormalities, or symptoms like drowsiness or muscle weakness may be mistaken for signs of aging. If a family member is managing the medication, pay attention to changes in appetite, state of consciousness, gait, vomiting, and bowel movement status.
The electronic package insert indicates that when administering to the elderly, one should consider reducing the dosage and administer with caution, such as by performing periodic serum magnesium level measurements.
Consult about blood tests if you have been taking it for a long time
Magnesium oxide is a medication that is sometimes prescribed for long periods depending on the symptoms. However, just because you have been taking it for a long time does not mean its safety is guaranteed, nor does it mean that because there have been no problems so far, there will be no problems in the future.
As you age, develop other illnesses, or become dehydrated, your kidney function and ability to excrete medication may change. Additionally, the risk of hypermagnesemia or drug interactions may change due to the addition of other medications.
If you have been taking it for a long time, check the following points during your medical consultation:
Are there any issues with the results of your kidney function tests?
Is it necessary to measure your serum magnesium levels?
Is your current dosage the minimum necessary?
Can the dosage be reduced according to the stool consistency?
Is there an option to switch to another constipation medication?
Furthermore, the electronic package insert states that there have been reports of stones forming in the stomach or intestines, leading to intestinal obstruction, when magnesium oxide is taken in large amounts over a long period. It is important not to increase the dosage on your own and to have the cause re-evaluated if constipation does not improve.
Be cautious of drug interactions with antibiotics, osteoporosis medications, and iron supplements.
Magnesium oxide may affect the absorption or excretion of other drugs by adsorbing them or changing the environment within the digestive tract.
In particular, tetracycline antibiotics, new quinolone antibiotics, and bisphosphonate osteoporosis treatments may have reduced absorption and fail to provide sufficient effects if taken at the same time as magnesium oxide. For iron supplements, digitalis preparations, and fexofenadine used for allergy treatment, it may also be necessary to take measures such as spacing out the doses.
However, it is not the case that 'a 2-hour interval is sufficient for all medications.' The necessary dosing intervals and order depend on the medications being taken concurrently.
Additionally, magnesium may be contained not only in prescription drugs but also in over-the-counter stomach medicines, constipation medications, and supplements. If you are visiting multiple medical institutions, present your medication notebook and have them check for any duplication of the same ingredients.
If a new medication is added after magnesium oxide has been prescribed, you also need to reconfirm the drug interactions. Please consult your doctor or pharmacist, as changing the dosing time on your own may affect the effectiveness of other medications.
Do not adjust the dosage on your own if diarrhea occurs.
Since magnesium oxide is a medication that softens stool, it may cause loose stools or diarrhea if the effect is too strong. Also, for those who already have diarrhea, it may worsen the symptoms.
If the stool becomes too soft, some people reduce the number of tablets on their own or stop taking them for several days. However, if the dosing method becomes inconsistent, it can become easier to alternate between constipation and diarrhea, making it difficult to determine the appropriate dosage.
During consultations, convey not only 'whether you had a bowel movement' but also the hardness of the stool, the frequency of bowel movements, the frequency of diarrhea, and the presence or absence of abdominal pain. Keeping a record of your stool condition for several days will be helpful for the doctor when adjusting the dosage.
Reasons why doctors prescribe magnesium oxide
In the survey presented, the following opinions are cited as the main reasons why doctors prescribe magnesium oxide.
It is easy to adjust the amount according to the stool condition.
The price of the medication is relatively low.
There is an impression that it is less likely to cause abdominal pain.
It has been used for many years and there is extensive experience in prescribing it.
Magnesium oxide is a medication that has been widely used for the purpose of softening stool. The fact that there are multiple tablet strengths and that it is easy to adjust the dosage while observing the stool condition can be an advantage for the prescribing side.
On the other hand, because it is a familiar medication, caution is required regarding its continued, aimless prescription. The electronic package insert also indicates that it should be used to the minimum extent necessary to prevent hypermagnesemia.
7 Points to Discuss While Taking Magnesium Oxide
People taking magnesium oxide should check the following points during medical examinations or medication guidance.
Is the stool becoming too soft with the current dosage?
Are there any issues with the results of kidney function tests?
Is it necessary to measure serum magnesium levels?
Is it necessary to continue taking the same amount for a long period?
Are there any issues with drug interactions with antibiotics, osteoporosis medications, iron supplements, etc.?
Is there any overlap in ingredients with over-the-counter drugs or supplements?
Are symptoms such as nausea, muscle weakness, drowsiness, or a slow pulse appearing?
Magnesium oxide is a constipation medication that draws water into the intestines to soften hard stool. It is widely prescribed in medical settings because it works through a different mechanism than stimulant laxatives and is easy to adjust in dosage.
However, just because it is the number one prescribed medication does not mean it is the most suitable for everyone.
People with reduced kidney function, the elderly, and those taking it for a long period need to be particularly careful about hypermagnesemia. Furthermore, even if kidney function is normal and the patient is taking less than the standard dose, the possibility of serious hypermagnesemia cannot be ruled out.
To use magnesium oxide safely, it is important to check not only the hardness of the stool but also kidney function, age, duration of use, concomitant medications, and even blood test results.
Summary | Consider Constipation Medications Based on Whether They Suit Your Symptoms, Not Rankings
The top 3 medications for chronic constipation frequently prescribed by doctors in 2026 were as follows.
1st place is magnesium oxide, 2nd place is Goofice, and 3rd place is Amitiza.
However, this ranking is not in order of "highest effectiveness" or "recommended order." It is the result of a survey on which medications doctors prescribe most frequently to patients with chronic constipation. The number one medication is not necessarily the best for everyone.
To briefly summarize the differences between each medication, Amitiza is a drug that acts on the small intestine to promote water secretion into the intestinal tract. While it softens stool and makes it easier to move, diarrhea, nausea, and abdominal pain may occur. Also, it cannot be taken by pregnant women or those who may be pregnant.
Goofice is a medication that suppresses the mechanism by which bile acids are reabsorbed in the small intestine, increasing the amount of bile acid that reaches the large intestine. It is characterized by acting not only on water secretion in the large intestine but also on intestinal movement. It is usually taken once a day before meals, but abdominal pain, diarrhea, and sudden bowel movements may affect daily life.
Magnesium oxide is a medication that draws water into the intestines to soften hard stools. While it is widely used and the dosage is easy to adjust, those who take it for long periods, the elderly, and those with reduced kidney function need to be cautious of hypermagnesemia. It is also necessary to check for interactions with antibiotics, osteoporosis medications, and iron supplements.
When choosing a constipation medication, it is important to check not only the frequency of bowel movements but also the consistency of the stool, whether you need to strain hard, if you have a feeling of incomplete evacuation, and whether you are experiencing abdominal pain or diarrhea. Kidney function, the possibility of pregnancy, duration of use, and interactions with other medications are also important information for selecting a medication.
Avoid assuming that a medication will suit you just because it is highly ranked, or increasing the dosage on your own if you feel the effect is weak. Conversely, if you are concerned about side effects, do not stop taking it suddenly on your own judgment; instead, inform your doctor or pharmacist about what symptoms are appearing and when they started after taking the medication.
Additionally, if you experience severe abdominal pain that is different from usual, repeated vomiting, bloody stools, sudden changes in bowel habits, or unexplained weight loss, it is important to see a medical institution rather than just monitoring the situation with constipation medication.
Constipation medications should be considered by matching the medication's action with your own physical condition, rather than by ranking. If you are unsure whether your current medication is right for you, bring your medication notebook and consult your doctor or pharmacist about your stool condition, side effects, underlying conditions, and the medications you are currently taking.
Reference
Nikkei Medical 'Nikkei Medical Prescription Drug Encyclopedia / Doctor Survey'
https://medical.nikkeibp.co.jp/leaf/mem/pub/series/survey/202604/592903.html
*The ranking in this article is based on the survey mentioned above. The ranking does not indicate the effectiveness, safety, or recommendation level of the medications. For information regarding the actions, dosage and administration, side effects, and contraindications of the medications, please check the latest electronic package inserts for each drug.
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