Magnesium for Constipation: Types, Benefits, Side Effects, and Dosage - GoodRx (2024)

Magnesium is the fourth most common mineral in the body. It’s important in helping the body work properly. It’s key in more than 300 different bodily functions — from muscle relaxation to maintaining a steady heartbeat.

In the right form and amounts, taking magnesium for laxative effects can also help your bowel movements stay regular. Let’s take a look at how magnesium can treat constipation, and what you should know before you try it.

Does magnesium make you poop?

Yes, magnesium can help you poop. When you take magnesium supplements, much of the mineral stays in the gut. This draws water into the bowels, which helps keep things moving. This is sometimes called an “osmotic effect,” and it’s why magnesium can be an effective laxative.

People take magnesium these days for many different reasons, from heart health to migraine relief. People have been using it for constipation for centuries. There are several formulations of magnesium supplements out there, and it helps to know the difference when it comes to treating constipation.

Types of magnesium for constipation

Magnesium supplements are easy to find over the counter. But there are a lot to choose from. They can come in the form of a liquid or tablet, and some are absorbed better than others. Let’s take a look at the different options.

1. Magnesium oxide

Magnesium oxide comes in the form of a powder or capsule.

Pros: It’s less expensive than other types of magnesium. And because it stays in the gut more than other formulations, it decreases the risk of developing dangerously high levels of magnesium in the blood.

Cons: Magnesium oxide for constipation can still cause high levels of magnesium in the blood, especially if taken over a long period of time. For this reason, people with abnormal kidney function or kidney disease shouldn’t take it.

Dosage: It typically comes in a 400 mg tablet. For some people, 1 tablet a day is enough to relieve constipation. But many people take it 2 to 3 times a day.

2. Magnesium hydroxide

Magnesium hydroxide is the liquid form of magnesium oxide, and is better known by its name Milk of Magnesia. It also comes as a tablet and chewable tablet, though this is less common.

Pros: It’s easy to find. And because it’s available in a chewable tablet and liquid, it may be a better option for children or people who don’t swallow pills easily.

Cons: For some people, the taste is very unpleasant. And similar to magnesium oxide, there’s a risk of magnesium toxicity.

Dosage: Each 15 mL of liquid contains 1,200 mg of magnesium. For adults and children 12 years and older, the dosage is generally 30 mL to 60 mL each day. This can be divided into two or three doses over the course of the day. The dosage for children 6 to 11 years old is half that amount — 15 mL to 30 mL a day.

3. Magnesium sulfate

Magnesium sulfate is better known in the U.S. as Epsom salt. Unlike in other countries, it’s not readily available in an oral form. But it can be found in certain mineral waters and can help with constipation.

Pros: Since some mineral waters naturally contain magnesium sulfate, some people consider it a more natural way to supplement magnesium.

Cons: It’s more difficult to find in an oral form in the U.S.

Dosage: This depends on the product because it comes in different strengths. But a typical dose of Epsom salt for constipation is 2 to 4 teaspoons dissolved in 8 oz of water taken once or twice per day.

4. Magnesium citrate

Magnesium citrate is another liquid form of magnesium that comes in a bottle.

Pros: It’s easy to find, and it can be mixed with other liquids (like juice) to make it taste better. Some people say it tastes like carbonated soda.

Cons: Taking magnesium citrate for constipation can require drinking a large volume of liquid. So even if it tastes better than other forms, it can still be hard to get down.

Dosage: The dosage for this form varies by age:

• Adults and children older than 12 years: The recommended dosage is 6.5 oz to 10 oz each day. This can be taken all at once, or divided throughout the day.

• Children between 6 and 11 years old: The dosage ranges from 3 oz to 7 oz.

• Children between 2 and 5 years old: The recommended dosage is 2 oz to 3 oz a day.

5. Magnesium glycinate

Magnesium glycinate is the combination of magnesium with an amino acid, called glycine. It’s more commonly used when someone has low levels of magnesium. This is because, unlike some of the other forms of magnesium above, this one gets absorbed into the bloodstream more readily than the other forms, which tend to stay more in your gut. This is why it can help raise magnesium levels in the blood.

Pros: Magnesium glycinate is a very absorbable form of magnesium. This is good for people who have low magnesium levels. It also means it has less gastrointestinal side effects for people who need it for this reason.

Cons: This formulation may be less effective if you’re taking it as a laxative. It can also lead to high levels of magnesium in the blood, which can potentially be dangerous.

Dosage: Magnesium glycinate typically comes in 100 mg to 400 mg capsules. Often people start with 100 mg but can work up to 400 mg.

Which magnesium is best for constipation?

There isn’t necessarily one type of magnesium that works better for constipation than others. It helps to try a few different types and see which one is most tolerable to you. People will have different preferences based on:

• Cost and availability at their local pharmacy

• The taste and form — some people may prefer a pill, while others may prefer a liquid

• The way it affects their body — you may find one form works better for you than others, or causes fewer side effects

So you can experiment with different forms. But if you’re wondering where to start, the easiest supplement to take is usually magnesium oxide in a pill form.

For children, the liquid formulations of magnesium hydroxide or magnesium citrate may be easier to swallow. And for smaller kids who may not drink a lot, magnesium hydroxide will likely be the best choice.

How long does it take for magnesium to start working to relieve constipation?

For most people, magnesium starts working when it reaches the bowel. You may see results as soon as 30 minutes, but it may take up to 6 hours. In cases of severe constipation, it may take longer.

What are the side effects of taking magnesium for constipation?

In general, magnesium at recommended amounts is safe. However, if you take too much, you may experience:

• Diarrhea

• Nausea or vomiting

• Abdominal pain

• Flushing

• Low blood pressure

In severe cases, it can cause breathing to slow, and the heart to beat irregularly. And there are some health conditions that increase the risk of health complications from magnesium supplements.

Can magnesium cause constipation?

Magnesium typically doesn’t cause constipation. If you’re having trouble with constipation and a magnesium supplement isn’t helping, it may be worth talking with your doctor or primary care professional.

Who should avoid taking magnesium for constipation?

People shouldn't take magnesium if they have the following conditions:

• Kidney disease: The kidneys play an important role in filtering excess magnesium out of the blood. So if someone has reduced kidney function, they’re at greater risk of dangerously high magnesium levels.

• Myasthenia gravis: Magnesium relaxes muscles. And this can be dangerous for people who have conditions that affect how their nerves control muscle contraction, such as myasthenia gravis. Extra magnesium in the body may cause them to become very weak.

It’s also important to know that magnesium can interfere with how other medications work. These include:

• Insulin

• Antibiotics and antivirals

• Heart medications, like digoxin

• Diuretics, like hydrochlorothiazide and furosemide

• Reflux medications, like omeprazole

If you take any of these medications, talk with your healthcare professional or pharmacist before taking any magnesium.