Some Types of Magnesium Can Cause Diarrhea—Here's One That Won't

Fact checked by Nick Blackmer

• Some forms of magnesium may be more likely to cause diarrhea based on how the body absorbs them.

• Magnesium oxide and magnesium citrate are two kinds of magnesium that may prompt this reaction.

• Magnesium glycinate, on the other hand, is less likely to cause someone to have diarrhea.

Is your magnesium supplement giving you diarrhea?

Magnesium supplements have grown popular on social media, with users claiming the mineral can support several health functions.

Many Americans are deficient in the nutrient: Some estimates suggest that up to 75% of people in the US don’t get enough magnesium through their diet.

“Most adults are not getting as much magnesium as they should,” Ayanna Lewis, MD, a gastroenterologist at Mount Sinai Health System, told Health.

Recent research has spotlighted the nutrient and its many potential benefits.

“There have been a lot of interesting studies on how magnesium affects different [conditions], from depression to restless leg syndrome,” Lewis said.

However, some people who start taking magnesium supplements may experience gastrointestinal issues like nausea, diarrhea, and abdominal cramping.

Here’s why magnesium may prompt diarrhea, as well as which forms of the supplement are less likely to have this effect.

Related: Before You Buy Magnesium Supplements From TikTok, Here’s What You Need to Know

The More Magnesium You Take, the More Likely It Is You’ll Get Diarrhea

It’s common knowledge that magnesium can make some people feel the need to go to the bathroom.

“In [our field] we actually use it to treat constipation,” Lewis explained.

This is because of magnesium’s effect on the gut, Saurabh Sethi, MD, a gastroenterologist based in Fremont, California, told Health.

“Magnesium attracts water into the intestines, leading to increased bowel movements,” he explained.

The more magnesium you take, the higher your chances of experiencing this side effect.

“Higher dosages are more likely to induce diarrhea,” Sethi said.

When considering any supplement—magnesium included—it’s important to understand dosage recommendations.

Women are supposed to get 310 to 320 milligrams of magnesium each day; men are supposed to get 400 to 420 milligrams. It's wise to not exceed these recommended amounts. And, the recommendations differ for people who are pregnant and for teens who are breastfeeding.

In general, it’s important to speak with a healthcare provider before you start new medications, including supplements.

“The key is to do this with your doctor, not in isolation,” Lewis said. “[You should] discuss them with your doctor because sometimes they have unintended effects.”

Magnesium Oxide and Magnesium Citrate More Likely to Cause Diarrhea

Two types of magnesium may be more likely to cause diarrhea than others.

“Magnesium oxide…works as an osmotic laxative, which means it draws liquid into the colon [and] into stool and gives the stool more bulk for people who are constipated,” Rabia De Latour, MD, a gastroenterologist at NYU Langone, told Health.

This type of magnesium is commonly used to treat constipation, so if you aren’t experiencing constipation and you take magnesium oxide, it could cause diarrhea.

“If you have normal bowel movements [and you try magnesium oxide], it can cause diarrhea by the same effect,” De Latour said.

Another common constipation treatment—magnesium citrate—may also be more likely to cause diarrhea.

“Magnesium citrate is absorbed better than others, and because it’s absorbed better, it can [have the effects of] higher doses,” Lewis explained.

Some people can avoid diarrhea by taking a form of magnesium called magnesium glycinate.

“Magnesium glycinate is often better tolerated,” Sethi explained. “The magnesium is combined with the amino acid glycine, making it more gentle on the gastrointestinal tract and more easily absorbed into the body… A lot of people find magnesium glycinate to be gentler on the digestive system.”

That said, taking too much of any kind of magnesium may cause diarrhea.

“Regardless of the formulation, if you take enough, it will have a laxative effect,” Lewis said. “If you take a lot of it, you’re going to get diarrhea.”

This, she said, is why it’s crucial to take only the recommended amount of supplemental magnesium.

Related: What Causes Diarrhea? 4 Possibilities

What to Do If Your Magnesium Supplements Are Causing Diarrhea

If you suspect your magnesium supplements are causing diarrhea—or if you’re looking to increase your magnesium intake and don’t want to take more pills—there are many ways to get more magnesium through your diet.

“Magnesium sources from food are probably better than magnesium supplements alone,” Dr. Lewis said. “The preference should be to try to get it from dietary sources.”

The following foods are good sources of magnesium:

• Legumes

• Nuts

• Seeds

• Whole grains

• Green leafy vegetables

• Fortified foods, such as some breakfast cereals

• Milk

• Yogurt

If you suspect your magnesium supplement is causing diarrhea and you need or want to continue taking supplemental magnesium, Sethi recommends trying a lower dose. It may also be worth trying magnesium glycinate if you’ve been taking another type.

If neither of those tips works, speak with a doctor to determine what to do next.

It’s important to seek help quickly if you’re having diarrhea and it doesn’t go away, since you can become severely dehydrated as a result.

“Always talk to your healthcare professional for personalized advice,” Sethi said.

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