Risks of Magnesium Supplements

Magnesium is essential to overall health 12. The mineral is involved in hundreds of reactions in the body, and adequate intake can help prevent chronic illnesses such as cardiovascular disease, Type 2 diabetes, osteoporosis, asthma, migraine headaches and depression. Magnesium can be found in most foods such as green vegetables, legumes and whole grains. Getting too much magnesium from food is rare, but most Americans do not get enough from their diets and often turn to supplements to fill in the gaps. However, too much supplemental magnesium can lead to serious health issues 1.

Abdominal Distress

Too much supplemental magnesium has been known to cause diarrhea, nausea, upset stomach and abdominal cramping. Magnesium carbonate, chloride, gluconate and oxide are most associated with these symptoms. Consuming large amounts of milk of magnesia, Epsom salts taken as laxatives or antacids can cause these symptoms.


Taking large amounts of supplemental magnesium -- typically more than 5,000 milligrams per day -- can lead to a serious health issue called hypermagnesemia, in which the level of magnesium in the blood reaches a toxic level. It can lead to extremely low blood pressure, nausea, vomiting, difficulty breathing, cardiac arrest and death. The risk of developing hypermagnesemia increases for those with reduced kidney function as the kidneys help remove excess magnesium from the body.

Drug Interactions

Magnesium supplements can interact with certain medications, potentially interfering with the medications' effects or the ability to absorb or excrete magnesium from the body. Magnesium supplements have been known to interact with medications for diabetes, blood pressure, diuretics and hormone replacement therapy. In addition, magnesium supplements can interact with antibiotics such as tetracycline, doxycycline and Cipro (ciprofloxacin). Talk with your doctor before taking magnesium supplements if you're on medication.

The Recommended Dietary Allowance for adults ages 19 to 30 is 310 milligrams of magnesium for women and 400 milligrams for men each day. After the age of 30, the daily requirements for magnesium increase to 320 milligrams for women and 420 milligrams for men. It's best to get magnesium from food as it is available in a variety of vegetables, fruits, whole grains, nuts, seeds and legumes. Men and women over the age of 19 should take no more than 350 milligrams of magnesium from supplements each day because of the risks associated with too much magnesium from supplements.