Can Magnesium Help With Constipation?
Most of us will experience constipation at some point in our lives. It’s the most common digestive complaint and the reason for millions of doctor visits each year. It happens when you have a bowel movement less than three times a week or when stools are hard and lumpy and uncomfortable or a strain to pass.
Magnesium is a mineral your body uses to regulate muscle and nerve function, blood sugar, and blood pressure, among other functions. When you take magnesium for constipation, it helps your small intestine absorb water. That increases the pulsing movement of the intestines (peristalsis) that enables bowel movements.
Here’s how to take magnesium laxatives safely and effectively.
What Are Some of the Reasons You Might Need Magnesium for Constipation?
Constipation can be due to several things, including:
- A lack of dietary fiber or water
- Not enough exercise
- Health conditions, including irritable bowel syndrome or some hormonal conditions
- Medication, including opioids and the weight loss and diabetes drugs GLP-1 agonists
The rise in popularity of GLP-1 medication for weight loss means more people might be having constipation as a side effect. According to Kyle Staller, MD, MPH, gastroenterologist at Massachusetts General Hospital and an expert for the American Gastrointestinal Association, “GLP-1 can cause constipation for people. Part of it is just a decreased calorie count, but there could be hormonal effects as well.”
GLP-1 medications reduce the amount of a hormone called glucagon-like peptide 1, which your body uses to stimulate insulin production. Insulin affects your digestion, and these medications can slow the movement of food through your digestive tract. That causes stool to remain in your system longer, where it can dry out and make it hard for you to go.
“Magnesium can be a relatively safe way to counteract that constipation,” says Staller. “It’s widely available and used in normal body processes. It certainly could be used for someone who's developed constipation as a result of taking these medications.”
If you are taking GLP-1 medication and have constipation, talk to your doctor. They may suggest several things, including:
- Dietary changes
- Exercise
- Increasing your water intake
- Eating more fiber
They can also advise you on magnesium or other laxatives.
What’s the Best Magnesium for Constipation?
There is more than one type of magnesium for constipation. Your choice of which one to take may come down to whether you prefer a pill, powder, or liquid. You may also find that one works better for you or has less side effects than another. They also vary in cost.
“I don't think there's a one size fits all when it comes to treating constipation,” says Staller. “The goal is to use things where there is some evidence that they work, don't cause too many side effects, and are not too expensive.”
Here's a comparison of different forms of magnesium:
Magnesium Oxide
Magnesium oxide is one of the most common forms of magnesium laxative and among the most studied. Like other forms of magnesium laxatives, it’s a salt made of magnesium and oxygen. Your intestines don’t absorb it as easily as some other forms of the mineral. This makes it less likely that your magnesium levels will become higher than they should be. It’s usually effective, inexpensive, and widely available. You take it as a capsule or tablet.
According to Staller, “I would say magnesium oxide is best is not because we know that it works better than the others, but we know what the normal dosing is that doesn't put you at risk for having too much magnesium. So magnesium oxide is the one that we tend to rely on.”
Magnesium Citrate
Magnesium citrate contains magnesium and citric acid. It’s easily absorbed in the intestines and usually comes as a liquid which can be further diluted. Doctors may prescribe it in higher doses than recommended for constipation to empty the bowels for a colonoscopy or other intestinal procedure.
Staller says, “It's never been studied for chronic constipation. Most people will be familiar with magnesium citrate as a rescue therapy. Meaning, when you really can't go, magnesium citrate can be a potent, over-the-counter treatment that can help people go.”
Magnesium Glycinate
Magnesium glycinate contains magnesium and the nonessential amino acid glycinate, which is an antioxidant found in high-protein foods. It’s available as a powder, gummy chew, or tablet. Your body absorbs it easily. But it’s usually taken by people who have low magnesium levels than for constipation. Magnesium glycinate has also become popular as a supplement to help treat symptoms of anxiety and insomnia, and there is some evidence it may offer benefits for those concerns.
No matter what form of magnesium you take, always follow the directions on the bottle or package for dosage and other instructions. These can include how much water to drink with it to avoid dehydration and help soften stool.
What’s the Best Time of Day to Take Magnesium for Constipation?
You can take magnesium before bed, as it may make you sleepy. But it can take anywhere from 30 minutes to 6 hours for a magnesium laxative to work. Take it when you know you’ll have easy access to a toilet and plenty of time to let the magnesium do its job. Also remember that it may lead to more than one bowel movement.
What About Milk of Magnesia?
Milk of Magnesia has been around since 1873 for use as a laxative and antacid. It is the liquid form of magnesium oxide and acts the same way as the capsules or tablets to relieve constipation. It is also available in a chewable tablet.
Are Epsom Salts Magnesium?
Yes, Epsom salts are magnesium, specifically magnesium sulfate. Epsom salts are widely available and usually come as a powder that you dilute with water to soak sore muscles. You can also mix it with water to take for constipation.
Magnesium for Constipation Dosage
Different forms of magnesium have different dosing instructions. It’s important to read them carefully and understand them for the type of magnesium laxative you plan to take. Follow the directions carefully.
Don’t take a magnesium laxative without talking to your doctor if you have:
- Stomach pain
- Nausea
- Vomiting
- Blood in your stool
Call your doctor if you don’t have a bowel movement after taking the medication if six hours have passed. If this happens, you may have a blockage or other underlying condition that needs medical attention.
Are There Side Effects of Too Much Magnesium?
Magnesium is generally considered safe, but it can sometimes cause diarrhea or cramping. It may also lead to nausea or vomiting.
Rarely, very high amounts of magnesium can cause severe side effects, including:
- Depressed breathing rate
- Irregular heartbeat
- Cardiac arrest
If you have kidney disease, you may not be able to take magnesium. This is because the kidneys filter excess magnesium out of the body. If your kidneys don’t work as well as they should, you’re at higher risk of your magnesium level getting too high.
Magnesium can also interact with other medications, including insulin and heart medications. So talk to your doctor about medications you are on before taking magnesium.
Chronic constipation is when you have difficulty with bowel movements about a quarter of the time. If this is true for you, talk to your doctor before taking magnesium for an extended period of time.
However, Staller notes, “There's always a worry that taking laxatives of any type could cause some damage to the colon. That's a common misconception. There's not a lot of evidence for these laxatives causing damage with long-term use. Using them according to the label, within the doses that were used in clinical trials, these are definitely something that could be used over the long term.”
If you don’t know what’s causing your chronic constipation, see your doctor. They’ll want to check for and address any underlying conditions.
Takeaways
Constipation, or lack of comfortable bowel movements, is very common. It can be due to a variety of causes, from lack of exercise or not enough fiber to GLP-1 agonist medications for obesity and diabetes.
Magnesium is a common and effective remedy for constipation. It’s available over the counter in several forms, including liquid, capsule, and powder. If your bowel movements are infrequent or difficult, magnesium could help.
You may have to try different types to see what works best for you. Magnesium oxide is one of the most common and least expensive forms of magnesium for constipation. But there are others, including magnesium citrate or magnesium sulfate (Epsom salts).
Make sure you follow the recommended dosage, and give yourself time to be near a bathroom when the medication takes effect. This can be anywhere from 30 minutes to 6 hours. You may have more than one bowel movement. Side effects can include diarrhea and nausea, although this is generally a safe medication.
