For those with kidney issues, magnesium supplements can pose significant danger. The kidneys are responsible for filtering excess minerals from the body — and when they aren’t functioning properly, magnesium can build up to toxic levels in the bloodstream.
According to medical professionals, this buildup can trigger a range of alarming symptoms:
- Irregular heartbeat
- Confusion or disorientation
- Extremely low blood pressure
- Weak or slowed breathing
- In severe cases, even coma or death
As WebMD explains, people with impaired kidney function simply can’t clear magnesium efficiently. That means even small doses that are safe for most people can become dangerous.
Doctors urge anyone with chronic kidney disease, reduced kidney function, or past kidney injury to avoid magnesium unless it’s specifically prescribed and closely monitored by a healthcare provider.
2. People Without a Magnesium Deficiency Don’t Need It
This warning might surprise many: if you’re not deficient in magnesium, taking extra won’t give you extra health benefits.
While magnesium deficiency is fairly common — estimates suggest that between 9% and 17% of adults, and up to 20% of teenagers, may have low magnesium levels — many people already get enough through diet. Foods like leafy greens, nuts, seeds, beans, and whole grains are rich sources of the mineral.
But despite the growing popularity of supplements, experts say that taking magnesium when you don’t need it is not only unnecessary — it can also cause uncomfortable side effects such as:
- Diarrhea
- Nausea
- Stomach cramping
- Vomiting
And if taken in very high doses, those mild symptoms can progress to more dangerous reactions like an irregular heartbeat or low blood pressure.
Dr. Noorhan Nassar, a primary care physician at Houston Methodist, explained:
“The data supporting benefits of magnesium supplementation in otherwise healthy adults isn’t complete. The results are mixed, and the design of many studies isn’t ideal.”
He also pointed out that magnesium is known to act as a natural laxative, which can cause digestive upset even at moderate doses.
Simply put, if you aren’t deficient, magnesium isn’t likely to improve your health — and in some cases, it may make you feel worse.
