Magnesium is an essential mineral that’s important for literally hundreds of bodily functions including muscle function, blood sugar control, and blood pressure regulation.
About half of Americans don’t get enough magnesium from food and beverages alone, so supplements could be helpful to fill in the gaps of your magnesium intake.
However, supplements often come in much higher doses than what you’d get from foods, so the risk of magnesium overdose (or hypermagnesemia) is much higher.
At best, magnesium overdose can cause diarrhea and abdominal cramps, but at worst it could lead to difficulty breathing, irregular heartbeat, and death. Severe magnesium toxicity isn’t all that common, but symptoms like diarrhea are more common if you’re taking a high dose supplement.
In this article, learn how much magnesium is safe to take, symptoms of a magnesium overdose, and what to do if you think you’ve taken too much magnesium.
Magnesium does so much for our bodies, so it’s important to consume enough of it. Amongst hundreds of other functions, we need magnesium to turn food into energy and to generate protein. You can find it in foods like nuts, seeds, green leafy vegetables, and whole grains, but if you don’t eat those foods very much then a supplement can help you meet your magnesium needs.
Magnesium supplements may also help with migraines, constipation, anxiety, and sleep.
The amount of magnesium you need each day depends on your age, sex, and whether you’re pregnant or lactating. Keep in mind that the recommendations below are for total intake of magnesium from foods and supplements combine:
- Birth to 6 months: 30 milligrams (mg)
- 7–12 months: 75 mg
- 1–3 years: 80 mg
- 4–8 years: 130 mg
- 9–13 years: 240 mg
- 14–18 years: 410 mg for males; 360 mg for females; 400 mg if pregnant; 360 mg if lactating
- 19–30 years: 400 mg for males; 310 mg for females; 350 mg if pregnant; 310 mg if lactating
- 31–50 years: 420 mg for males; 320 mg for females; 360 mg if pregnant; 320 mg if lactating
- 51+ years: 420 mg for males; 320 mg for females
To prevent a magnesium overdose, it’s important to be aware of the tolerable upper intake levels (ULs) for magnesium. These are purely for magnesium supplements, not foods, and they vary based on your age.
Taking a magnesium supplement could cause some unpleasant side effects, even if you’re not exceeding the UL. Diarrhea is one of the most common side effects since magnesium can draw water into the stool to soften the stool. These digestive side effects are more likely with magnesium oxide or magnesium citrate since these forms are commonly used for treating constipation.
The symptoms of magnesium overdose can be quite severe because of all the roles magnesium plays in the body. In fact, overdosing on magnesium can lead to muscle paralysis and serious cardiac issues like cardiac arrest.
Earlier signs of magnesium overdose include nausea, dizziness, weakness, and confusion. If magnesium levels continue rising, symptoms like slowed reflexes, headache, flushing, and blurred vision can occur.
Magnesium overdose actually isn’t that common, but certain groups are at higher risk of magnesium overdose. They include:
- Those with impaired kidney function: The kidneys help excrete magnesium, so those with acute kidney injury or chronic kidney disease are more likely to experience magnesium overdose.
- Those taking magnesium supplements: Not surprisingly, consuming high doses of supplemental magnesium—often for treating constipation—makes it more likely you’ll overdo it.
- Those taking certain medications: Some medications, like anticholinergics or opioids, can increase magnesium absorption, which increases the chance of a magnesium overdose.
- Pregnant people with eclampsia: Since high doses of intravenous magnesium are commonly used to help prevent eclamptic seizures, pregnant people with eclampsia are considered a high-risk group for magnesium overdose.
