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Constipation is defined as having infrequent passage of stools or difficulty eliminating stools. About 15% of the population experience it, with a higher prevalence in people designated female at birth and 65 and above.
Common symptoms of constipation include the following:
Inadequate fluid and fiber intake and lack of physical activity are some of the causes of constipation.
Other causes include metabolic disturbances, medications, neurological disorders, muscle-related diseases, and structural disorders, as follows:
Regular bowel movements are essential for digestive health because they help remove waste products from your body and prevent the build-up of toxins.
The following article covers the uses of magnesium for constipation and its safety concerns.
Magnesium is a nutrient and mineral that plays a vital role in many processes in the body, including the following functions:
The amount of magnesium that you need daily depends on your age and other factors, such as the following:
Magnesium comes in the following forms:
Magnesium in aspartate, citrate, lactate, and chloride forms is generally more easily absorbed than the oxide and sulfate forms.
Foods are a fantastic way to get your magnesium needs met. Foods that are sources of magnesium include the following:
Magnesium is recognized as a gentle and effective remedy for relieving constipation. The recommended maximum tolerable intake of magnesium for adults is 350 mg per day to prevent overdose.
While generally safe when used as directed, certain precautions are necessary. Individuals with diagnosed kidney disease, elevated magnesium and potassium levels, and low calcium levels should be cautious and refrain from using magnesium for constipation.
Although considered safe for short-term use, prolonged reliance on magnesium may result in dependence.
If you have ongoing digestive issues, contact your healthcare provider or ask for a referral to a registered dietitian nutritionist for further guidance about what foods and other techniques may support your digestive health and well-being.
Certain medical conditions, such as alcoholism, poorly controlled diabetes, Crohn’s disease, ulcerative colitis, and chronic kidney disease, can increase the risk of magnesium deficiencies.
Some medications can lower magnesium levels, including the following:
Early signs of magnesium deficiency include the following:
More severe symptoms include:
The use of magnesium supplements can help address magnesium deficiencies. However, organic-bound magnesium salts such as the following are recommended for treating magnesium deficiency due to their higher absorption rate:
Magnesium works as an osmotic laxative to relieve constipation by increasing the water content and volume of the stool. As a result of magnesium’s ability to draw water into the intestines, the stool softens, and the swollen stool stimulates intestinal motor activity, promoting bowel movements.
Several guidelines recommend the use of magnesium salts for constipation. However, some guidelines from Germany do not recommend the use of osmotic laxatives, such as magnesium hydroxide, for chronic constipation due to possible side effects.
A study was conducted in 34 female subjects with an average age of 40 and mild to moderate constipation. The results showed that using magnesium oxide for four weeks improved overall constipation symptoms. However, the sample size was small and limited to female subjects from Japan.
Another study conducted in 90 people with chronic constipation found that overall symptom improvement was observed in 69.2% of the senna group (stimulant laxative), 68.3% in the magnesium oxide group, and 11.7% in the placebo group (an inactive substance). However, the majority of the research subjects were female. Therefore, the results might not be the same in other populations.
Various magnesium salts are used as osmotic laxatives, but few studies compare the different salt forms. The following includes the recommended forms of magnesium supplements for constipation relief, their pros and cons, dosage, and more.
As suggested, magnesium oxide has been studied for constipation. The following includes its typical dosage and its pros and cons:
The following dosage of magnesium hydroxide is based on 400 mg of magnesium hydroxide per 5 milliliters (mL) suspension:
Each dose should be taken with 1 full cup of water (8 liquid ounces) once a day at bedtime or in divided doses. Pros and cons include:
Magnesium citrate has been used for constipation as well. The following includes its typical dosage:
Drink 1 cup of liquid with each dose. Magnesium citrate may be taken as a single daily dose or in divided doses. Pros and cons include:
Magnesium sulfate, commonly known as Epsom salts, has also been used for constipation. The following includes its typical dosage:
Magnesium sulfate can be taken as a single daily dose or in divided doses.
To improve the taste, you may add some lemon juice. Pros and cons include:
The following magnesium salts are considered saline laxatives:
They draw water into the intestines, softening the stool and making it easier to pass.
Studies suggest magnesium citrate is a more potent saline laxative. Besides being used for constipation, magnesium citrate is also used to empty the bowel in preparation for colonoscopy, a procedure used to screen for colon cancer and any abnormalities in the bowel.
Although magnesium oxide is associated with diarrhea, its low absorption rate suggests that it may have less of a tendency to cause high magnesium levels in the body than other forms of magnesium.
Each salt form comes in different formulations, such as tablets, powder, suspension, liquid, and granules, and may have other uses in addition to constipation.
For example, magnesium hydroxide (milk of magnesia) is also used as an antacid.
Therefore, the form of magnesium used for constipation is individualized.
Magnesium hydroxide, citrate, and sulfate generally produce a bowel movement within 30 minutes to six hours.
Magnesium supplements can cause diarrhea, nausea, and vomiting.
The types of magnesium most commonly reported to cause diarrhea include magnesium carbonate, chloride, gluconate, and oxide.
Symptoms of magnesium toxicity include the following:
Avoid magnesium if you're allergic to it or its components (parts). Seek immediate medical attention if you have a severe allergic reaction (itching, hives, shortness of breath).
The kidneys are responsible for regulating magnesium levels in the blood. However, if you have kidney problems, the risk of magnesium buildup increases.
Therefore, people with poor kidney function should avoid magnesium due to an increased risk of heart block or increased magnesium levels in the blood.
When taking magnesium, caution should be taken if you:
The risk of developing high magnesium levels in the blood increases with decreased kidney function and large daily doses of magnesium supplements.
Guidelines from Japan recommended that blood magnesium concentrations be measured periodically in older adults and people using magnesium oxide for prolonged periods.
Magnesium decreases the efficacy of certain medications and supplements, including:
Be sure to space out the time between taking magnesium supplements and antibiotics (doxycycline, ciprofloxacin, and azithromycin) and other medications by at least two hours.
High doses of zinc supplements can interfere with magnesium absorption in the body.
Diuretics or water pills, such as Lasix can increase the loss of magnesium in the urine.
The use of proton-pump inhibitors (acid-reducing drugs) such as Nexium (esomeprazole) or Prevacid (lansoprazole) for more than a year can cause low magnesium levels.
The laxative effect of magnesium oxide is decreased when taken with acid-reducing drugs, such as Pepcid (famotidine) or Prilosec (omeprazole).
The following drugs may increase magnesium levels in the blood:
In the United States, the Food and Drug Administration (FDA) does not regulate supplements like prescription drugs. This means some supplement products may not contain what the label says.
When choosing a supplement, look for third-party-tested products and consult a healthcare provider, registered dietitian nutritionist (RDN or RD), or pharmacist.
Approaches recommended to prevent and manage constipation include the following:
Maintaining a regular bowel movement is important for digestive health.
Various forms of magnesium, such as magnesium oxide, hydroxide, citrate, and sulfate, are used for constipation due to their ability to draw water into the intestines.
Please consult with your healthcare provider before starting magnesium supplements if you have certain medical conditions, such as kidney problems, or take certain drugs.
Magnesium oxide, hydroxide, magnesium citrate, and magnesium sulfate are classified as saline laxatives. Studies comparing the various forms of magnesium among each other are needed to clarify which type of magnesium is best for constipation. However, magnesium citrate is generally suggested to have a stronger laxative effect than other magnesium preparations.
Magnesium works for constipation by retaining fluids in the intestines, which softens the stool and makes it easier to pass. Because magnesium interacts with some medications and should be avoided in people with certain medical conditions, please consult your healthcare provider to determine if a magnesium-based laxative is appropriate.
How much magnesium citrate is used for constipation?For adults and children 12 years of age and over, the dose is half a bottle to one bottle (10 fluid ounces). For children six to 11 years of age, the dose is one-third to one-half of a bottle (3 to 5 ounces). For children under 6 years of age, please consult a healthcare provider. Be sure to drink 8 ounces of water with each dose (can be taken as a single daily dose or in divided doses).
11 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
By Trang Tran, PharmD
Tran is a Doctor of Pharmacy and an integrative health and wellness freelance writer based in Oregon.
