You’ve likely heard that magnesium is an essential mineral that’s involved in hundreds of bodily processes—including muscle and nerve function. It’s also been having a moment lately because of its relaxing and sleep-inducing effects (looking at you, sleepy girl mocktail). What you might not know, though, is that when you’re backed up, magnesium may actually help you poop.

While most people can get all of the magnesium they need (anywhere from 320 to 420 milligrams per day) by eating magnesium-rich foods—including nuts, seeds, leafy greens, beans, whole grains, salmon, bananas, and potatoes—some people may need a magnesium supplement if they’re deficient or have certain health concerns, like constipation, per the National Institutes of Health (NIH).

Here’s the lowdown on how magnesium helps you poop, the best kind to take for constipation, how much to take, and when it’s time to go to your doc about being backed up.

Does magnesium help constipation?

If you’re having trouble pooping, magnesium can help by making your stool softer and easier to pass. “In the GI tract, non-absorbed magnesium is an osmotic laxative, which means it secretes more water and electrolytes into the gut to help things move forward and improve constipation,” says Elena Ivanina, DO, MPH, founder of the Center for Integrative Gut Health in New York City.

Magnesium is actually a common ingredient in over-the-counter (OTC) laxatives like MiraLax, Milk of Magnesia, and Citroma. But you can get the same benefits just from taking a magnesium supplement, says Dr. Ivanina. You just need to take the right type of magnesium.

The best magnesium for constipation relief includes:

• Magnesium oxide: This may be your best bet, according to recent guidelines from the American College of Gastroenterology and the American Gastroenterological Society. There’s good evidence to show it works to relieve chronic constipation, so if adding more fiber to your diet isn’t cutting it, you can try magnesium oxide before moving on to a stimulant laxative or other products.
• Magnesium citrate: This type can relieve occasional constipation by softening your stool and encouraging your intestinal muscles to move poop out, says the Cleveland Clinic.
• Magnesium sulfate: It also has laxative properties that can help you poop, per the Mayo Clinic.

In general, you shouldn’t take magnesium or other laxatives for more than a week unless you’ve been told by your doctor to do so, says the National Library of Medicine (NLM). If you’re regularly relying on laxatives to help you poop, that could be a sign of an underlying GI problem that needs to be addressed.

Other types of magnesium and their uses

There are actually a bunch of different types of magnesium supplements, and different types can be used for different health problems. Here are the most common, which you can often find in the vitamin aisle at your local drugstore:

• Magnesium chloride (for low magnesium levels, per the NIH)
• Magnesium aspartate (for low magnesium levels, per the NIH)
• Magnesium glycinate (which may support mood and sleep, per the Mayo Clinic)
• Magnesium hydroxide (which may relieve heartburn, and can also have a laxative effect, per the Harvard T.H. Chan School of Public Health. This type is also found in the OTC medication Milk of Magnesia.)
• Magnesium lactate (for low magnesium levels, per the NIH)
• Magnesium malate (which may help with muscle pain, per Mount Sinai)
• Magnesium sulfate (which may help with muscle pain, per the Mayo Clinic)

How much magnesium should I take for constipation?

Most magnesium supplements come in 500-milligram tablets or capsules, per Michigan Medicine. Most experts recommend starting with 500 milligrams, but ask your doctor about the right amount for you. Dr. Ivanina recommends taking it in the evening (maybe after dinner, because it could cause irritation if you take it on an empty stomach). “In general it can often help produce bowel movements the next day,” she says.

The NLM also recommends taking magnesium with 8 ounces of water if you’re constipated, because downing some extra fluids can also help move things along. And if you’re on any prescription meds, take them at least 2 hours apart from the magnesium to avoid any potential interactions.

A TIP:

Talk to your doctor if you’re unsure about whether you can take magnesium with your current prescription medications.

Can you take too much magnesium?

While it’s possible to take too much magnesium, the average healthy person would need to take a lot (think: 5,000 milligrams or more per day) in order to run into problems like magnesium toxicity, which can potentially be fatal. But even moderately high doses (like over the recommended 500 milligrams per day) can mess with your stomach and make you crampy, nauseous, or give you diarrhea, per the NIH.

Other potential signs of magnesium toxicity include the following, per the NIH:

• Nausea
• Vomiting
• Facial flushing
• Urine retention
• Lethargy
• Muscle weakness
• Shortness of breath

Call your doctor and seek emergency medical care if you feel any of these effects after taking magnesium.

Risks or side effects of too much magnesium

Again, high doses of magnesium can mess with your stomach and make you queasy or nauseous. And because it works as a laxative, there’s a good chance that overdoing it will give you diarrhea. Doses above 5,000 milligrams per day could be toxic, per the NIH.

It’s especially important to check in with your doctor before taking magnesium if you have a kidney problem, because the kidneys are responsible for getting rid of excess amounts of the mineral, says Dr. Ivanina. (So if they’re not working as well as they should, extra magnesium could build up in your body.)

Finally, keep in mind that magnesium can interact with other medications. These include the following, per the NIH:

• Biphosphonates (such as Fosamax and Boniva), used to treat osteoporosis
• Antibiotics
• Diuretics
• Prescription acid reflux medications
• Very high doses of zinc supplements

If you take any of these medications, check with your doctor before adding a magnesium supplement to your routine.

Other ways to poop easier

Magnesium supplements can help you poop when you’re really backed up. But if you’re dealing with regular or frequent constipation, lifestyle changes might be needed to really solve your poop problem. In this case, try to:

• Eat a high-fiber diet: Aim to get between 22 and 34 grams of fiber per day, from foods like beans, whole grains, fruits, and vegetables. Options like berries, peaches, apricots, plums, and ground flaxseeds are especially good for getting things moving, per the NLM.
• Drink plenty of fluids: Drinking enough water and/or other hydrating beverages can make your stool softer and easier to pass. In fact, an older and frequently cited study in Hepatogastroenterology¹ found that drinking around 8 cups of liquids per day with a high-fiber diet improved constipation more than a high-fiber diet alone.
• Exercise regularly: Moving your body can keep things moving in your gut, too, per Harvard Health Publishing. Try to do something active every day, even if it’s just taking a walk around your neighborhood or on the treadmill, or following a yoga or Pilates video.
• Check your position: Squatting, leaning back, raising your feet, or even rocking back and forth on the toilet can make it easier to poop, according to the Cleveland Clinic. (Squatty Potty, anyone?)

When to see a doctor about constipation

We all get constipated from time to time and it’s usually no big deal. But you should let your doctor know if you’ve gone more than three days without pooping, are in a lot of pain, have blood in your poop, or are constipated and also throwing up, according to the NLM. These could be signs of an underlying GI issue that needs to be treated.

FAQ

Is it okay to take magnesium daily?

It’s generally safe to take 500 milligrams of magnesium daily. That said, needing to take magnesium every day in order to poop is a red flag that something else might be going on. You could have an underlying GI problem that needs to be addressed, or you might just need to make some lifestyle changes (like more fiber!) to support better bowel habits, says Dr. Ivanina.

Can magnesium soften your stool?

Magnesium oxide is an osmotic laxative, which curbs constipation by bringing more water into your gut, which helps make your stool softer and easier to pass. Though keep in mind: it’s not categorized as a stool softener (like docusate sodium), which is a different type of medicine that “lowers the surface tension of stool, allowing more water to easily enter the stool,” says Dr. Ivanina.

What is the best stool softener for constipation?

Turns out, stool softeners like docusate sodium (i.e., Colace) actually aren’t that effective for helping you poop, so they’re not usually recommended by GI docs, says Dr. Ivanina. Magnesium oxide, which is a type of osmotic laxative, is actually a better choice, and the one that’s recommended by the American College of Gastroenterologists and the American Gastroenterological Society.

—reviewed by Jennifer Gilbert, MD, MPH