5 serious side effects of magnesium supplement

Not everyone needs a magnesium supplement – most people can meet their needs through food. But if you take one, be aware of potential side effects: diarrhea is common and, in rare cases, excess magnesium can cause potentially fatal toxicity.

1. Diarrhea and stomach aches

Taking too much magnesium can cause diarrhea because it can act as an osmotic laxative, attracting water into the intestine. You can also have other gastrointestinal symptoms such as nausea, vomiting and cramps.

Certain forms of magnesium, such as oxide, are more likely to cause diarrhea because they are not well absorbed. Other types such as glycinate, lactate, l-theonate and malatic are less likely to cause gastrointestinal side effects because they are better absorbed by the body.

Any supplement with more than 350 mg of magnesium can also trigger diarrhea, which can cause dehydration if it persists over time.

2. Cardiac problems

High doses of magnesium can disturb the electrical system of the heart, which could be particularly dangerous if you have irregular heartbeat.

Although magnesium is an essential electrolyte that supports normal heart function, excess magnesium could cause symptoms such as chest pain, palpitations, low blood pressure and in serious cases, cardiac arrest.

3. Respiratory removal

Very high doses of magnesium can interfere with signals which control breathing, leading to respiratory depression – a slow or irregular breathing rate. This can happen if excess magnesium weakens or paralyzes the muscles used for breathing.

In serious cases, magnesium overdose can cause respiratory stop, which can be fatal without immediate medical care.

‌4. Neurological effects

Very high levels of magnesium can affect the brain and the nervous system, leading to symptoms such as drowsiness, confusion, lethargy and depression. This can also cause muscle weakness, abnormal reflexes, paralysis and convulsions.

In serious cases, the toxicity of magnesium can alter consciousness or lead to a coma, and these effects can be irreversible or even fatal without rapid treatment.

5. Complications related to the kidneys

Although magnesium deficiency can be dangerous for people with chronic kidney disease, having an excess magnesium can also affect the kidney function.

When the body cannot eliminate excess magnesium, it can accumulate at dangerous levels. People with chronic kidney disease or kidney failure are more at risk of serious side effects and should consult a health care provider before taking magnesium supplements.

Can you die of magnesium toxicity?

A dangerously high level of magnesium in the blood – called hypermagnesisemia – can be fatal. In rare cases, people can die of magnesium overdose, especially if they have underlying health problems.

Children, the elderly and people with an altered renal or hepatic function are more at risk because their bodies may not effectively erase magnesium, increasing the probability of serious complications.

How much magnesium is too much?