Updated 20th July 2023
Can magnesium help with constipation?
Magnesium can help relieve constipation, and it’s available over the counter. You might see it as “magnesium citrate” in laxative medications.
It’s a mineral that supports the chemical reactions that control your blood sugar, blood pressure, and how your nerves and muscles work. Magnesium also plays other roles in your body.
If you’re finding it hard to poop or don’t often feel the urge, you might have constipation. And while magnesium can help, there are other approaches to consider.
Laxative medications shouldn’t be your first choice, Dr. Will Bulsiewicz, a board-certified gastroenterologist and U.S. medical director of ZOE, explained on a recent ZOE Science & Nutrition podcast episode.
“It's common for people to head straight to the pharmacy to pick up whatever medication is available to treat their constipation. And sadly, in many cases in our healthcare systems, the doctors will recommend these things,” he said. “But I personally think that we need to start with diet and lifestyle.”
How magnesium works
When magnesium reaches your intestines, it helps draw in water. Your dry poop absorbs the water, which makes the poop easier to pass. This type of laxative is called an osmotic.
There are different types of magnesium, and not all work as laxatives. Here are the ones that help you poop:
magnesium hydroxide (milk of magnesia)
How long does it take to work?
If you don’t notice a bowel movement in this time frame — and you’ve tried other ways to make pooping easier — speak with a doctor.
If laxatives aren’t doing anything, it could point to an underlying issue that needs investigating.
Other ways to make pooping easier
As Dr. B mentioned, making changes to your diet and routines can help provide some regularity to your poops.
Here are some strategies to try before you take constipation medication or supplements:
Drinking plenty of water
Dehydration is a common cause of constipation. Try starting with 6–8 cups of water a day, and see if that helps.
Eating more whole plant foods
Adding high-fiber plant foods, like apples, chia seeds, green vegetables, kiwis, and legumes, can move your poop along.
“By increasing our whole plant food intake, we’re actually increasing our fiber intake,” Dr. B said.
“And when we reduce our ultra-processed food intake in combination with this, we ultimately are guiding ourselves toward a poop that’s more microbiome-friendly.”
Snacking on prunes
Having certain dried fruits, like prunes, is a great way to up your fiber intake.
Prunes also provide sorbitol, a sugar alcohol with laxative effects. In one small study, a daily serving of 100 grams of prunes provided chronic constipation relief.
The reason for this isn’t clear yet, but exercise might make your stomach muscles work harder or release gut hormones that promote pooping.
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Probiotics are live bacteria that can benefit your health. They naturally exist in some fermented foods, like some yogurts and sauerkrauts. Manufacturers can also add them to foods or sell them as supplements.
Unpublished ZOE research suggests that people who eat probiotics poop more often.
In our study — the largest nutrition science study in the world — we saw that participants who ate more probiotics had more bowel movements than those who didn’t eat any.
The odds of pooping most days went up by around 10% when participants consumed one type of probiotic. This increase was around 15% if they ate fermented dairy, other fermented foods, and took probiotic supplements.
Responses to coffee vary from person to person.
For some, it might make pooping easier. A review of research indicates that coffee can encourage the movement of food through the gut, in some cases.
While there’s no guarantee that coffee will have this effect on you, it may be a low-risk option.
Scientists aren’t sure why coffee gets the bowels moving for some people. It may stimulate gut muscles, but overall, we need more research.
To hear more about what Dr. B has to say about constipation, you can listen to the ZOE Science & Nutrition podcast episode here.
If changing your diet and routine don’t have the desired effect, you might consider an over-the-counter magnesium laxative.
|Try half to a whole 10-fluid-ounce bottle.
|Try 2–6 teaspoons.
|Try 2–4 tablespoons.
|Try a third to half a bottle.
|Try 1–2 tsp.
|Try 1–2 tbsp.
|2–6 years of age
|Speak with a doctor first.
|Speak with a doctor first.
|Try 1–3 tsp.
You can take each of these as a single dose or divide them throughout the day. Drink a full glass of liquid with each dose.
Side effects and risks
Consuming a lot of magnesium from a laxative can lead to these side effects:
nausea and vomiting
There’s far more magnesium in laxatives than in foods that contain the mineral. One tbsp of magnesium hydroxide provides 500 milligrams of magnesium.
If you consume very high doses of magnesium — more than 5,000 mg a day — there’s also a risk of magnesium poisoning.
The symptoms include:
low blood pressure
nausea and vomiting
a fast or irregular heartbeat
Who shouldn’t take magnesium for constipation?
Magnesium products are available without a prescription. But speak with a doctor if you’re:
pregnant or trying for pregnancy
still constipated after using a different laxative for 1 week
currently taking other medication
aware that your bowel habits have been different for more than 2 weeks
having stomach pain, nausea, or vomiting
a person with kidney disease or diabetes
on a low-magnesium or low-salt diet
Food sources of magnesium
A balanced, nutritious diet will contain all the magnesium you need.
One study from the United States looked at dietary magnesium intake and chronic constipation.
After analyzing participants’ daily number of poops, the researchers found that consuming more magnesium was associated with less constipation.
It’s best to get the mineral through foods rather than supplements. Good sources of magnesium include:
|Magnesium per serving (mg)
|% of the daily value
|Roasted pumpkin seeds
|Dry roasted almonds
|Cooked black beans
|Shelled, cooked edamame beans
|Smooth peanut butter
|Cooked brown rice
The recommended daily allowances of magnesium are as follows:
males aged 14–18: 410 mg
males aged 19–30: 400 mg
males aged 31 and above: 420 mg
females aged 14–18: 360 mg
females ages 19–30: 310 mg
females ages 31 and above: 320 mg
If you’re pregnant, the recommended allowances are higher.
It’s worth noting that many of these foods have other benefits related to constipation. For example, chia seeds provide soluble fiber, which dissolves in water to form a gel that softens your poop.
Almonds, on the other hand, are an excellent source of insoluble fiber. This makes your poops heavier and easier to pass through your gut.
At ZOE, we know that each of us responds to foods differently. Our research shows that eating the best foods for you can keep your gut healthy and provide plenty of other health benefits.
To learn more about how our personalized nutrition program works, you can take our free quiz.
Laxatives that contain magnesium may help relieve constipation. But it’s better to see if adjusting your food choices, drinking more water, and being more physically active will do the trick before you try a medication.
You can get magnesium from your diet in certain whole plant foods, like pumpkin and chia seeds, almonds, and boiled spinach.
Magnesium citrate, hydroxide, and sulfate are medications that could help unleash your bowel movements within 6 hours.
But they can cause side effects, and certain people should speak with a doctor before trying them.
Association of dietary magnesium intake with chronic constipation among US adults: Evidence from the National Health and Nutrition Examination Survey. Food Science & Nutrition. (2021). https://onlinelibrary.wiley.com/doi/full/10.1002/fsn3.2611
Diet in irritable bowel syndrome: What to recommend, not what to forbid to patients! World Journal of Gastroenterology. (2017). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5467063/
Effects of coffee on the gastro-intestinal tract: A narrative review and literature update. Nutrients. (2022). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8778943/
Exercise therapy in patients with constipation: A systematic review and meta-analysis of randomized controlled trials. Scandinavian Journal of Gastroenterology. (2019). https://pubmed.ncbi.nlm.nih.gov/30843436/
Exploratory comparative effectiveness trial of green kiwifruit, psyllium, or prunes in US patients with chronic constipation. American Journal of Gastroenterology. (2021). https://pubmed.ncbi.nlm.nih.gov/34074830/
High fiber diet. StatPearls. (2023). https://www.ncbi.nlm.nih.gov/books/NBK559033/
Label: Epsom salt — magnesium sulfate granule. (2022). https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=e985e071-5541-456e-ae4d-dba85287fe75
Label: Magnesium citrate saline laxative — magnesium citrate liquid. (2022). https://dailymed.nlm.nih.gov/dailymed/lookup.cfm?setid=29091600-a3ca-4346-bdeb-651131b90e2f&version=4
Label: Magnesium hydroxide liquid. (2011). https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=c29995d6-e8f2-4e7b-aa03-6ce5aa0e7710
Magnesium. (2022). https://ods.od.nih.gov/factsheets/Magnesium-HealthProfessional/
Magnesium oxide in constipation. Nutrients. (2021). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7911806/
Risk factors for constipation in adults: A cross-sectional study. Journal of the American College of Nutrition. (2020). https://www.tandfonline.com/doi/abs/10.1080/07315724.2020.1727380
Rome IV criteria. (n.d.). https://theromefoundation.org/rome-iv/rome-iv-criteria/
Water, drinks and hydration. (2023). https://www.nhs.uk/live-well/eat-well/food-guidelines-and-food-labels/water-drinks-nutrition/
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