Can Magnesium Make You Poop or Help With Constipation?

Key takeaways:

• Magnesium, a mineral, is essential for many bodily functions.
• Magnesium helps muscles in the colon move food through the digestive system.
• While magnesium citrate is sometimes prescribed for constipation, magnesium oxide may put you at less risk of taking too much magnesium.

Magnesium is frequently used in various forms to treat constipation. This mineral is crucial in managing many bodily functions and also helps regulate muscles and nerves. Magnesium occurs naturally in the body, but some people need an extra boost from time to time.

Magnesium treats constipation by increasing water absorption in the small intestine. That increased water helps food move through the digestive tract, which can relieve constipation.

In general, magnesium oxide is thought to provide better dosing with less risk of too much magnesium. We’ll explore some of the ways magnesium interacts with your digestive system and identify symptoms that should prompt a call to your doctor.

Does magnesium help with constipation?

Magnesium has been used to treat constipation since the 17th century, when magnesium sulfate was discovered in Epsom, England.

This discovery became known as Epsom salts. Magnesium is available in different preparations, with magnesium oxide commonly recommended for the treatment of constipation.

Does magnesium cause more frequent bowel movements?

Magnesium acts on the smooth muscles of the intestine to increase the movement of food through the colon. As a result, bowel movements can be more frequent after taking magnesium supplements.

How long it takes for magnesium to affect bowel movements

It can take 30 minutes to six hours for magnesium to affect your bowel movements.

Choosing the right magnesium for digestive health

A variety of magnesium preparations are available to improve your digestive help and relieve constipation. Stomachache, nausea, vomiting, and diarrhea are common side effects.

Magnesium oxide

Magnesium oxide is often prescribed for constipation. It has a low side effect profile. Magnesium oxide is cheaper than many other forms of magnesium used to relieve constipation.

It also tends to remain in the digestive tract longer than other preparations. A recent study showed magnesium oxide to be effective for the relief of mild to moderate constipation.

Magnesium citrate

Magnesium citrate is often used as a bowel prep for colonoscopy. It can also be used for occasional constipation. It is in a class of laxatives called saline laxatives, which work by drawing water into the colon through osmosis.

Magnesium citrate works by promoting the retention of water in the stool. This softens the stool, allowing for easier passage of bowel movements. It also increases the number of bowel movements. It usually works quickly, sometimes within 30 minutes.

Magnesium hydroxide

Magnesium hydroxide is also known as Milk of Magnesia. It comes as a liquid, tablet, or chewable tablet.

Thirty milliliters of the liquid contains 2400 grams of magnesium. Adults and children over 12 usually take 30–60 milliliters daily for constipation. The dose can be divided throughout the course of the day.

Magnesium sulfate

Magnesium sulfate is better known as Epsom salts. Epsom salts are not available for oral consumption in the U.S.

However, many mineral waters contain magnesium sulfate, which can help regulate bowel movements and treat constipation.

Magnesium glycinate

Magnesium glycinate is usually used to supplement magnesium levels in people with hypomagnesemia (low magnesium.)

It usually has fewer gastrointestinal side effects than other forms of magnesium. However, it may also be less effective than other forms of magnesium for the treatment of constipation.

Foods with high magnesium levels

Foods with a high fiber content, like whole grains, legumes, fruits, and vegetables, usually have a high magnesium content. Coffee, meat, dairy products, seeds, and nuts are good sources of magnesium. Mineral water typically contains magnesium.

Potential side effects of magnesium supplements

Magnesium is critical for many bodily functions, including healthy bone formation, muscle and nerve function, and food movement through the intestine. Magnesium supplements are commonly used to treat a variety of conditions. However, magnesium can result in the following side effects:

Stomach upset

Although magnesium can relieve constipation and reduce stomach acid, it can also cause an upset stomach and nausea or vomiting in some people.

Diarrhea

Because magnesium works by drawing water into the colon and speeding up food transportation through the digestive tract, it can sometimes cause diarrhea. If this happens, stop taking your supplements until the diarrhea resolves.

Hypermagnesemia

If you take too much magnesium, you might experience hypermagnesemia, or magnesium toxicity.

Symptoms of this condition include a rapid heart rate, low blood pressure, muscle weakness, and respiratory depression. In some cases of overdose, arrhythmia, coma, and death can occur.

Read our guides on how to encourage bowel movements and foods that can help you pass a bowel movement for more.

When to see a doctor about infrequent bowel movements or constipation

You should see your doctor about any change in your bowel movement that lasts a long time or doesn’t respond to home remedies or supplements. Below are some key concerns that should prompt a call to your healthcare provider.

You should see a doctor if you have any of the following associated with your constipation:

• Blood in your stools
• Constipation lasting longer than two weeks
• Constipation that doesn’t improve with home remedies or over-the-counter supplements
• Stomach pain associated with your constipation

You should go to the emergency room if, along with constipation, you:

• Cannot pass gas or stool
• Have severe or constant abdominal pain
• Have low back pain
• Have blood in your stool or rectal bleeding
• Have a fever or chills
• Are vomiting

Questions to ask your doctor about infrequent bowel movements or constipation

Asking your doctor the following questions may help you understand how to relieve your constipation.

• How can you determine the cause of my constipation?
• Do I need to change the food I eat to prevent future constipation?
• How much fluid should I drink to prevent constipation?
• Should I add fiber to my diet? If so, how much fiber do I need?

Frequently asked questions: magnesium and bowel movements

Magnesium affects many systems in the body, but its effects on bowel movements are essential. People taking magnesium or considering adding a magnesium supplement to prevent constipation often ask the following questions.

How can you tell if you are pooping too much after taking magnesium?

Diarrhea is defined as more than three or more loose or watery stools in 24 hours. If you are taking magnesium and develop frequent loose stools, the two may be correlated. Specific forms of magnesium, including magnesium oxide and magnesium citrate, are more likely to cause diarrhea.

Can too much magnesium make you constipated?

Magnesium has laxative effects, so it will not typically cause constipation if you take too much.

However, the effects of too much magnesium (hypermagnesemia) include nausea and vomiting, urinary retention, low blood pressure, and facial flushing. These effects can progress to muscle weakness, cardiac arrhythmia, difficulty breathing, coma, and death in extreme cases.

What if your stool changes color after taking magnesium?

If your stool changes color and remains that way for longer than a day, call your doctor.

There may be an underlying condition causing your stool to change color. If your stool is black, tarry, or bloody, you should call your doctor immediately or seek urgent care.

Take-home message: magnesium and constipation

Magnesium is essential for many bodily functions. Magnesium supplements are frequently used to treat constipation. Too much magnesium supplementation, however, can have harmful effects, so consult with your doctor before you start taking these kinds of supplements. If you experience any troublesome symptoms, call your doctor.

General Medicine follows a strict editorial process, including using real experts to write our articles, vetted primary sources, fact-checking, a secondary medical review, and updates as necessary. This article was medically reviewed and fact checked by Dr. Adam Carewe, MD.

Sources

Akhtar, Mohammad Irfan, et al. “Magnesium, a drug of diverse use.” JPMA. The Journal of the Pakistan Medical Association vol. 61,12 (2011): 1220-5.

Mori, Hideki, et al. “Magnesium Oxide in Constipation.” Nutrients vol. 13,2 421. 28 Jan. 2021, doi:10.3390/nu13020421

"Magnesium Citrate: MedlinePlus Drug Information." MedlinePlus - Health Information from the National Library of Medicine, National Library of Medicine, Apr. 2019, medlineplus.gov/druginfo/meds/a619019.html#why. Accessed 8 Nov. 2024.

Mori, Sumire, et al. “A Randomized Double-blind Placebo-controlled Trial on the Effect of Magnesium Oxide in Patients With Chronic Constipation.” Journal of Neurogastroenterology and Motility vol. 25,4 (2019): 563-575. doi:10.5056/jnm18194

Siegel, Jonathan D, and Jack A Di Palma. “Medical treatment of constipation.” Clinics in colon and rectal surgery vol. 18,2 (2005): 76-80. doi:10.1055/s-2005-870887