3 Signs You're Taking Too Much Magnesium, According to Dietitians
Magnesium is a valuable mineral for many reasons. Found in peanut butter, oatmeal, black beans, brown rice, yogurt, bananas and more, it can help with a variety of health concerns.
For example, maybe a dietitian or doctor encouraged you to get more magnesium to regulate your blood pressure, boost gut health, promote strong bones or maintain muscle function. After all, a magnesium deficiency might increase the risk of heart disease. Magnesium can also be transformational for sleep and anxiety. These are only some of the benefits. Getting enough magnesium every day is vital-enough said.
However, as beneficial as magnesium can be (and even though it's a "good" thing, a mineral), it is, in fact, possible to take too much. As the saying goes, you can have "too much of a good thing." You might not even realize that's happening, either, since the symptoms it can cause aren't specific to consuming too much magnesium. Plus, you might not realize that many well-loved foods are magnesium-rich (aka, you may not need a supplement). Further, taking too much magnesium can actually worsen your health in multiple ways, according to experts.
Ahead, dietitians share three signs you're taking too much magnesium, the dangers it can cause and how much magnesium is recommended.
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3 Signs You're Taking Too Much Magnesium, According to Dietitians
1. You have diarrhea
Dietitians are clear: The #1 sign you're taking too much magnesium is diarrhea.
"A lot of people don't realize certain forms [magnesium citrate] work almost like a laxative, so if you suddenly notice loose stools or stomach upset after starting a supplement, your body is probably telling you to scale back," says Jessica Brantley-Lopez, MBA, RDN, founder of The Eat Well Studio.
Kirsten Jackson, a UK-based registered consultant dietitian known as "The IBS Dietitian," explains why. "Magnesium that is not absorbed into the body ends up in the large bowel, where it draws in water that can lead to urgent loose stools."
2. You're dealing with nausea and stomach cramping
Along those lines, other GI problems can result from too much magnesium. You don't need to have diarrhea to be mindful of your magnesium intake.
According to Jackson, nausea and stomach cramping are "very common signs, particularly when someone is taking high doses or more poorly absorbed forms, such as magnesium oxide or citrate."
Related: Magnesium Glycinate Vs. Citrate: Which Magnesium Supplements Should You Be Taking?
3. Your blood pressure is low
GI issues aren't the only ones. Low blood pressure is, too, and it's "one of the more serious signs," according to Brantley-Lopez.
"Because magnesium helps relax blood vessels, too much can sometimes leave people feeling dizzy, lightheaded, weak, nauseous or even faint, especially if they already tend to run on the lower side with blood pressure, are dehydrated or take blood pressure medications," she explains.
She recalls experiencing this herself after receiving a vitamin IV supplement.
What Happens if You Take Too Much Magnesium?
Experiencing any of those three symptoms is bad enough. Not only are they unpleasant, but they can cause further problems. For example, diarrhea can lead to dehydration.
Related: The 3 Most Important Things Your Poop Reveals About Your Health, According to Gastroenterologists
When it comes to a magnesium overload, that's not all. "In more serious cases, especially for someone with kidney problems, excess magnesium can affect blood pressure, muscle function and even heart rhythm," Brantley-Lopez says.
Jackson adds muscle weakness, feeling unusually warm, extreme tiredness or drowsiness, slow heartbeat, confusion and even difficulty breathing (the latter in severe cases), particularly if someone overwhelms their body with magnesium for a long time.
However, for what it's worth, Brantley-Lopez clarifies that "true toxicity is rare" and more likely to happen because of magnesium supplements than magnesium-rich foods.
How Much Magnesium Is Recommended?
While too much magnesium is a problem, so is too little. What's the happy medium?
The Recommended Dietary Allowance says women need around 310 to 320 mg daily and men need around 400 to 420 mg daily. Brantley-Lopez recommends getting it from food sources, such as pumpkin seeds, leafy greens, beans, nuts, avocados, bananas and whole grains.
According to Jackson, most people get enough magnesium through their diet, and supplemental use is "not routinely recommended."
Related: ‘I'm a Family Medicine Doctor-Here Are the 2 Supplements I Take To Stay Healthy and Well'
With that said, she shares a warning: A magnesium deficiency usually doesn't happen on its own. "If someone is deficient, then they would also be deficient in multiple other micronutrients because magnesium is found in nuts, whole grains, a whole range of foods."
If you do take magnesium as a supplement, remember that different types exist, and the difference between them matters. For example, magnesium glycinate is more effective for sleep and relaxation, while magnesium citrate is often used for constipation.
"I always tell people not to just grab the highest dose on the shelf; the form matters, too," Brantley-Lopez says.
In short, more isn't always better-perhaps especially when it comes to magnesium.
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Sources:
- Jessica Brantley-Lopez, MBA, RDN, is the founder of The Eat Well Studio.
- Kirsten Jackson is a UK-registered consultant dietitian known as "The IBS Dietitian."
- Magnesium, Harvard T.H. Chan School of Public Health
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This story was originally published May 22, 2026 at 11:25 AM.