{"id":635846,"date":"2026-04-14T09:30:28","date_gmt":"2026-04-14T13:30:28","guid":{"rendered":"https:\/\/www.singlecare.com\/blog\/?p=635846"},"modified":"2026-08-13T10:47:57","modified_gmt":"2026-08-13T14:47:57","slug":"side-effects-of-too-much-magnesium","status":"publish","type":"post","link":"https:\/\/www.singlecare.com\/blog\/side-effects-of-too-much-magnesium\/","title":{"rendered":"8 side effects of too much magnesium"},"content":{"rendered":"

Magnesium is an essential mineral and electrolyte involved in hundreds of processes in your body. Among its health benefits<\/a>: It supports nerve and muscle function, helps the body produce energy, helps regulate blood pressure, aids in controlling blood sugar levels, contributes to bone health, and even aids in producing DNA and RNA. In short, it\u2019s a powerhouse.<\/p>\n

While you can get magnesium<\/a> from food sources like spinach, legumes, and brown rice, many people turn to supplements for the added benefit. Be advised: You can absolutely get too much of a good thing. In fact, it can be dangerous. Here, we\u2019ll break down eight mild, severe, and sometimes, well, inconvenient<\/i>, side effects of taking too much magnesium.\u00a0<\/p>\n

8 side effects of too much magnesium<\/h2>\n

\u201cWhen I first started taking magnesium, I took a higher dose before bed, thinking a little more would help me recover from working out. Wrong!\u201d says Ashley Kitchens, RDN<\/a>, registered dietitian and owner of Plant Centered Nutrition in Durham, North Carolina.\u00a0<\/p>\n

There are many known side effects of taking too much magnesium, ranging from mild to extremely dangerous:<\/p>\n

1. Diarrhea<\/h3>\n

\u201cThe most typical signs of too much magnesium are diarrhea and abdominal cramping,\u201d says Erika Gray, Pharm.D.<\/a>, founder and chief medical officer at ToolBox Genomics.com<\/a>. This happens because when magnesium doesn\u2019t get absorbed, the excess sits in your intestines and pulls water into your bowels. This has a laxative effect, causing loose, runny stool.\u00a0<\/p>\n

\u201cThe next morning after taking too much magnesium, I woke up, and my digestive system had very urgent opinions,\u201d warns Kitchens. \u201cThis is why I recommend starting low and going slow, because it may save you an urgent trip to the bathroom.\u201d<\/p>\n

Not all magnesium is created equal. Using certain forms of magnesium, such as magnesium citrate,<\/a> magnesium oxide, or magnesium hydroxide, can increase the risk of diarrhea due to their osmotic effects in the gut. If you already have bowel issues, talk to your provider about trying magnesium glycinate<\/a>, which has a high absorption rate.\u00a0<\/p>\n

2. Abdominal cramping, nausea, and vomiting<\/h3>\n

If you\u2019re spared the diarrhea, you may still experience side effects like stomach cramps and nausea. In more severe cases, vomiting may occur. There are a few reasons this could happen. The first is that unabsorbed magnesium acts as an osmotic laxative, pulling water into your intestines. This can lead to bloating and cramping (and, eventually, diarrhea).\u00a0<\/p>\n

The second reason you may feel nauseous after taking a magnesium supplement<\/a> is that the mineral can sometimes irritate the lining of your stomach. The mineral also relaxes smooth muscles, including those in the gut. Slower gut motility can disrupt your normal digestion, potentially making you feel sick to your stomach (literally).\u00a0\u00a0<\/p>\n

3. Fatigue<\/h3>\n

If you live with chronic fatigue and stress, your medical provider might recommend taking magnesium. Fatigue and stress are highly connected, and research has shown magnesium may help reduce cortisol levels<\/a>, especially among people with a magnesium deficiency.<\/p>\n

On the flip side, taking too much magnesium can actually cause fatigue. Although the mineral may regulate gamma-aminobutyric acid (GABA), a neurotransmitter that slows brain activity, fatigue may be a sign of hypermagnesemia. High magnesium levels could lead to weakness, lethargy, and drowsiness, which may need medical attention.\u00a0<\/p>\n

4. Low blood pressure<\/h3>\n

If you take magnesium and suddenly the room is spinning, it\u2019s likely because the mineral has caused a drop in your blood pressure. This is a rare side effect, but it’s possible. Magnesium relaxes everything, including your blood vessels. Some people even take magnesium to prevent high blood pressure. Unfortunately, taking too much could lead to hypotension<\/a>, which can cause confusion, dizziness, and even difficulty breathing.\u00a0<\/p>\n

This is a potentially serious side effect of too much magnesium and something you should discuss with your healthcare provider.<\/p>\n

5. Muscle weakness<\/h3>\n

Is too much relaxation a thing? Yes, it is, especially when it comes to your muscles. Magnesium relaxes your muscles<\/a>, acting as a balance to calcium, which triggers muscle contractions. This balance is key for normal muscle movement.<\/p>\n

Unfortunately, too much magnesium can have toxic effects, resulting in muscle weakness and slower reflexes. Magnesium toxicity is rare and a higher risk in people with kidney disease or those taking excessive amounts of magnesium.<\/p>\n

6. Arrhythmia (irregular heartbeat)<\/h3>\n

Of the many hats magnesium wears, one of the most interesting is its role in regulating your heartbeat<\/a>. The electrolytes magnesium, calcium, and potassium control the electrical signals in your heart:<\/p>\n