Magnesium is a generally safe supplement with a great deal of health benefits. However, with its popularity rising, it’s a fair question to ask: can you overdose? Will the combined dosage of magnesium from supplements and in food sources be enough to cause an overdose? Let’s unpack this.
Magnesium Benefits
Magnesium (Mg) is not only beneficial but necessary for basic bodily functions. It’s critical for things like bone health, nerve action, DNA synthesis, and energy production. Remember learning how the “mitochondria is the powerhouse of the cell” in biology class? Magnesium is a key player in many of those cellular processes.
Luckily, it’s available in lots of common food sources. The body also stores about 25 gm of magnesium on average, much of which is held in the bones and soft tissues, with only a small amount available in the blood.
Consuming enough magnesium is important to staying healthy in the long run. Consistent magnesium deficiency may contribute to things like osteoporosis, heart disease, and hypertension. It’s likely that Americans are widely magnesium deficient.
Many people have begun adding magnesium supplements into their diet for a variety of reasons. Mg aids in bodily processes that help promote sleep and reduce fatigue. There’s also reason to suspect it may aid in reducing anxiety symptoms.
However, like all things in life, there must be a balance. Too little magnesium isn’t good, but that doesn’t mean overloading on supplements is good, either. Let’s take a look at what happens when you get too much magnesium.
Is it possible to eat too much dietary magnesium?
It’s unlikely that a magnesium overdose would come from only eating too many magnesium-rich foods. While many foods contain this essential nutrient— like pumpkin seeds, brown rice, and spinach — the body typically only absorbs 30% to 40% of dietary magnesium.
The reason for this low absorption is that food in the gut readily bonds to magnesium, like fiber and phosphates. However, the status of Mg in the body also determines absorption— the body will absorb more if its status is low. Magnesium also has a laxative effect.
The recommended daily allowance (RDA) for magnesium from all sources is 310-360 mg per day for adult women and 400-420 mg for men (source). This includes the magnesium you get from food sources as well as supplements.
The recommended upper limit for only magnesium supplements/medications is 350 mg a day for anyone over the age of 19.
Taking magnesium supplements that are better absorbed by the body— like solutions that dissolve easily in water — can increase the amount of absorbed magnesium. Therefore, it’s important to be mindful when adding magnesium supplements into the diet and consult with a healthcare professional.
Types of Magnesium
There are several different types of magnesium, including but not limited to:
- Magnesium oxide which is often prescribed as a laxative
- Magnesium citrate which has a higher rate of absorption
- Magnesium L-threonate which delivers Mg to the brain effectively
- Magnesium acetyl taurate which has been associated with lowering anxiety indicators
What happens if you take too much magnesium?
The body uses magnesium to maintain balance with concentration gradients. When the concentration of Mg is too high in the blood, it causes an imbalance, and the body’s fluids act to return the concentration to normal. So in practice, if you take too much magnesium, you could end up with diarrhea.
If the body cannot filter out the magnesium, then the body’s gradients cannot regain balance, and processes such as nervous system action are affected.
If you have a kidney-related health condition, excess magnesium could cause severe side effects. However, if you take too much magnesium and have healthy kidneys, it will filter out of your body with time. Regardless, monitor the situation and call the Poison Help line immediately if symptoms of an irregular heartbeat, extreme drowsiness, or muscle weakness occur.
Can you overdose on magnesium?
It is rare but possible to overdose on magnesium supplements. If you have a condition that affects your kidneys, then you may be at a greater risk for magnesium overdose as your kidneys filter out excess Mg in your body.
Hypermagnesemia is a condition where the concentration of magnesium in the blood is much higher than is normal. It’s more likely to occur when the kidneys are malfunctioning. If the kidneys are healthy, taking too many magnesium supplements may result in symptoms like nausea and abdominal cramps, but is usually not a reason for concern.
High doses of magnesium in laxatives and antacids may also contribute to too much magnesium in the body when taken to excess.
Other conditions that increase the likelihood of magnesium overdose include:
- Hypothyroidism
- Milk-alkali syndrome
- Eclampsia
Magnesium Overdose Symptoms
Symptoms of initially taking too much magnesium include:
- Nausea
- Diarrhea
- Stomach cramping
More severe symptoms of magnesium overdose include:
- Irregular heartbeat
- Muscle weakness
- Urinary retention
- Low blood pressure
- Shortness of breath
- Headache
- Blurred vision
Have a question we didn’t cover? Call the Missouri Poison Center
Magnesium is an important nutrient, and having enough in the diet can have many health benefits. Consulting with a healthcare professional is the best course of action when deciding to add supplements to your diet, especially if you are part of a group that is susceptible to hypermagnesemia.
If you suspect a magnesium overdose or have any concerns about magnesium toxicity, call the Missouri Poison Center at 1-800-222-1222. Our experts are available 24/7 to provide free, confidential advice.
Magnesium Supplement Safety: Frequently Asked Questions
| Question | Answer |
|---|---|
| Can I overdose on magnesium if I take it with food? | While taking magnesium with food can help reduce gastrointestinal side effects, it doesn’t prevent overdose. Always follow the recommended dosage on the label or as prescribed by your healthcare provider. If you suspect an overdose, call the Poison Help line immediately at 1-800-222-1222. |
| Are there any household products that contain high levels of magnesium that could be dangerous if ingested? | Yes, some laxatives, antacids, and Epsom salts contain high levels of magnesium. Keep these products out of reach of children and pets. If accidental ingestion occurs, don’t wait for symptoms to appear – call the Poison Help line right away. |
| How quickly do symptoms of magnesium overdose appear? | Symptoms of magnesium overdose can appear within 30 minutes to a few hours after ingestion. However, the onset and severity can vary depending on the amount ingested and the individual’s health status. If you suspect an overdose, seek medical attention immediately. |
| If I miss a dose of my magnesium supplement, should I double up the next time? | No, never double up on doses of magnesium supplements. Taking too much magnesium at once can lead to toxicity. If you’re unsure, consult your healthcare provider or call the Poison Help line for guidance. |
| Can magnesium interact with other medications I’m taking? | Yes, magnesium can interact with various medications, including antibiotics, bisphosphonates, and some blood pressure medications. Always inform your healthcare provider about all medications and supplements you are taking. If you’re concerned about a potential interaction, don’t hesitate to call the Poison Help line at 1-800-222-1222. |
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Suggested APA citation:
Missouri Poison Center Trending Topics Blog. (2025, February 5). Can You Overdose on Magnesium and What Are the Symptoms?. Missouri Poison Center. https://missouripoisoncenter.org/magnesium-overdose/