Taking too many magnesium supplements or magnesium-containing medications can result in a magnesium overdose or toxicity. A magnesium overdose, which results from high levels of magnesium in the blood, is called hypermagnesemia .
Magnesium is a vital mineral that aids in muscle and nerve function and energy production. It also helps to keep bones strong and has a role in regulating blood sugar and blood pressure. Most people can get all the magnesium they need from their diet, while others take magnesium supplements to meet their daily requirements. 10389-08-9
Symptoms of too much magnesium in the body are gastrointestinal troubles, muscle weakness, headache, low blood pressure (hypotension), and facial flushing. Untreated hypermagnesemia can lead to severe symptoms, and extremely high levels of magnesium can be fatal for some people.
Magnesium overdose or toxicity is rare in most healthy people but can occur in people taking magnesium supplements or those with impaired kidney function. Some laxative and antacid medications contain high amounts of magnesium and should not be taken in high doses or for long periods.
This article will cover the symptoms of too much magnesium, sources of magnesium, toxic levels, treatment for overdose, and more.
The symptoms of hypermagnesemia typically won’t be felt until magnesium levels are incredibly high. When there are signs or symptoms, they may include:
More severe signs and symptoms of hypermagnesemia include:
People do not get too much magnesium through diet alone because the kidneys excrete excess magnesium into the urine. However, if taking magnesium supplements or medications that contain magnesium, it is possible to take too much and have health consequences.
The tolerable upper intake levels for magnesium from supplements or medications are:
These levels are the same for people of all sexes, including those who are pregnant or lactating (breastfeeding). Exceeding these levels may result in diarrhea, cramping, and nausea. These levels do not include magnesium from dietary sources, only magnesium from supplements or medications.
Taking amounts of 5,000 mg per day can result in magnesium toxicity. This might happen by taking a very large dose of laxatives or antacids that contain magnesium. Toxicity can produce severe symptoms, including low blood pressure, weakness, difficulty breathing, irregular heartbeat, and death.
Most people can get all the magnesium they need from their diet, while others take magnesium supplements to meet their daily requirements.
Magnesium is widely available in plant and animal food sources. The best dietary sources are leafy green vegetables (i.e., spinach), nuts, seeds, legumes, and whole grains. Tap and mineral water also have magnesium, but the amounts vary by source and brand.
It is not possible to get a magnesium overdose from diet alone. This is because the kidneys will eliminate any excess amounts during urination.
Magnesium supplements come in various forms, including
Magnesium is also found in over-the-counter (OTC) medications, especially laxatives and antacids. These include:
If you take supplements or OTC medications, follow the product’s labeling or your healthcare provider's instructions. Do not take more than the recommended daily amounts.
Magnesium toxicity is rare because your kidneys help rid the body of excess magnesium. An overdose might occur in someone with poor kidney function, especially if they take medications that contain high levels of magnesium or are taking supplements.
Toxic levels may occur in people who have been taking high doses of magnesium supplements for long periods. Risks are also higher for people with heart problems or gastrointestinal diseases.
A pregnant person who is being treated for preeclampsia (high blood pressure in pregnancy) is at risk for hypermagnesemia if they have been prescribed a high dose to prevent seizures. But this is rare because the magnesium is prescribed for a short period, usually less than 24 hours. A healthcare provider will also monitor you for signs of toxicity during treatment.
People who take laxatives and antacids for extended periods may have an increased risk for hypermagnesemia. Lower amounts and doses of these medicines are generally not dangerous, and the body will usually flush them out with urination and bowel movements.
However, larger doses of laxatives and antacids (more than 5,000 mg per day) can lead to magnesium toxicity. Accidental poisonings can occur when a child or adult ingests too much of these products. While rare, such excessive amounts of magnesium in the body could be fatal.
If you think you or someone else might be experiencing symptoms of a magnesium overdose, seek medical attention. This is especially important if you have been taking high doses of magnesium supplements, have a kidney disorder, or have another chronic disease.
The first treatment for magnesium toxicity is to stop taking supplements or medicines containing magnesium. Magnesium levels can decrease within a day or two after supplements or magnesium-containing medicines have been stopped. With lower levels, symptoms should improve.
A person with severe hypermagnesemia is often treated with calcium gluconate with an intravenous (IV) drip (through a vein in the arm) to block any toxic effects of the magnesium.
Diuretics (medicines that cause the kidneys to excrete excess fluid through urination) might also be given orally or by IV to help increase urination and help the body filter out the excess magnesium levels.
If you have a kidney disorder, your kidneys cannot process magnesium efficiently. In this case, severe hypermagnesemia will need to be treated with dialysis to clear the magnesium.
Kidney dialysis is a process of removing excess water and toxins from the kidneys. It uses a filtering machine that removes waste and fluid from the blood and then returns the filtered blood back to the body.
You can take magnesium supplements to meet your daily magnesium requirements. A healthcare provider might prescribe supplements if you have a magnesium deficiency.
You should talk to your healthcare provider before starting a supplement. They can assess your blood magnesium levels and advise you whether it is safe to take supplements based on your unique health situation.
Research shows that around half of Americans do not get enough magnesium in their diets. This can lead to uncomfortable symptoms and severe health problems.
Fatigue, loss of appetite, muscle cramps, weakness, and stiffness are early signs of low magnesium levels, or a magnesium deficiency, but these symptoms can worsen if not treated. Severe symptoms of a deficiency include abnormal heart rhythms and seizures.
The Office of Dietary Supplements at the National Institutes of Health recommends the following dietary allowances for magnesium for adults:
Magnesium recommendations for children are much lower, as follows:
Verywell Health acknowledges that sex and gender are related concepts, but they are not the same. To reflect our sources accurately, this article uses terms like “female,” “male,” “woman,” and “man” as the sources use them.
People sometimes take magnesium supplements to address specific health concerns, such as migraine, bone and joint health, high blood pressure, and type 2 diabetes.
It is important to check with a healthcare provider to see whether these supplements are recommended for you and what level will be safe to take. Also, magnesium might interact with medications, including bisphosphonates (used to treat osteoporosis) and antibiotics, reducing the absorption of these medications.
Magnesium is a key electrolyte, but that doesn't mean everyone needs a supplement. A registered dietitian can work with you to create an eating pattern that contains enough magnesium. If you are considering a magnesium supplement, chat with your doctor first.
Magnesium is a vital element for your overall health and well-being. But too much of it could lead to health problems, including digestive troubles, low blood pressure, and an irregular heartbeat.
Magnesium toxicity and overdose are rare. However, some people have a higher risk, including people with impaired kidney function and those taking high-dose magnesium supplements or magnesium-containing medications (such as antacids or laxatives) for long periods. You cannot overdose on magnesium from diet.
Severe hypermagnesemia could be fatal in someone with a kidney disorder. However, early treatment can improve outcomes. Treatment includes stopping supplements, intravenous calcium gluconate, diuretics, and dialysis in people with impaired kidney function.
If you are taking magnesium supplements and suspect you are experiencing magnesium toxicity, you should seek medical help immediately. You should not start magnesium supplements without first talking to your healthcare provider.
You can get magnesium from your diet. Supplements might help you meet your daily recommended amounts or correct a magnesium deficiency.
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By Lana Barhum Lana Barhum has been a freelance medical writer since 2009. She shares advice on living well with chronic disease.
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