Magnesium is an essential mineral found naturally in many foods and your body. However, as with most supplements and nutrients, there are risks associated with taking in too much.
While magnesium from food sources is generally considered safe because the kidneys filter out excess amounts, you need to pay attention to the amount of the mineral in any supplements you take.
Risk of Magnesium Overdose
The risk of ever experiencing a magnesium overdose is low for a healthy person, and taking magnesium via quality dietary supplements should be safe if you follow the guidelines and ensure you're taking modest doses. It always pays to be prepared, however, so read on for more...
A magnesium overdose can lead to a condition known as hypermagnesemia, which occurs when there is too much magnesium in your blood.
So, how easy is it to overdose on magnesium? What are the benefits of this mineral when taken appropriately? And how best should you take it to benefit from its full effects?
Before adding magnesium supplements to your diet, it is recommended to consult with a healthcare professional.
Find out all you need to know in this article!
Key Takeaways
- Magnesium is essential for muscle function, bones, blood pressure, and energy production, but too much can still be harmful.
- A true magnesium overdose (hypermagnesemia) is rare and usually linked to excessive supplemental intake or impaired kidney function.
- Most people are more likely to be low in magnesium than to get too much from food alone, making smart supplementation helpful.
- Staying within evidence-based daily doses and choosing well-absorbed forms reduces the risk of side effects like diarrhea, nausea, or low blood pressure.
- Magnesium taken correctly can safely support relaxation, sleep quality, and overall health as part of your nightly routine.
What is Magnesium and Magnesium Deficiency?
Magnesium serves many functions in the body, including protein synthesis, bone formation, blood pressure regulation, energy production, muscle function, and nerve function.
Many of us can manage to get an adequate intake of magnesium through diet alone, however, deficiency is still quite common, so supplementation is often necessary.
Magnesium Intake in the United States
Dietary surveys in the United States consistently show that many people do not consume enough magnesium.
Data from the National Health and Nutrition Examination Survey (NHANES) 2017–March 2020 show that around 30–50% of U.S. adults fall below the Estimated Average Requirement (EAR) for magnesium, even when intake from food and supplements is included. This suggests that inadequate magnesium intake remains common across the population. (1)
As well as dietary factors, particular risk factors for magnesium deficiency are alcohol abuse, older ages, people with malabsorption conditions, and people with Type 2 diabetes mellitus. (2)
Magnesium deficiency can lead to symptoms such as muscle cramps, fatigue, and may contribute to osteoporosis and serious health issues like heart irregularities and seizures. Additionally, magnesium deficiency has been linked to an increased risk of heart disease and hypertension. (3, 4)
Supplementation of magnesium has been shown to possibly:
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Keep bones strong and protect against osteoporosis
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Help with depression and anxiety
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Lower blood pressure
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Alleviate headaches and migraines
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Improve sleep. (5)
How Much Magnesium to Take?
The recommended daily intake of magnesium for healthy adult men is 400-420mg and 310-320mg for healthy adult women.
The recommended daily allowance (RDA) for magnesium includes magnesium from all sources, including food and supplements.
Pregnant women are recommended to consume a higher dose of magnesium than women who aren’t pregnant (350-360mg), but should be cautious with supplementation to avoid exceeding recommended dosages or magnesium overdose.
Please speak to a healthcare professional about prenatal vitamins. It is important to monitor levels of magnesium during pregnancy to ensure both deficiency and excess are avoided. (6)
Too much magnesium from food does not appear to typically pose any health risks, so ensure you are topping up your dietary magnesium before opting for a supplement.
Dietary Magnesium: Magnesium Rich Foods
Some of the best sources of magnesium rich foods include:
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Almonds
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Cashews
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Peanuts and peanut butter
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Spinach
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Bread
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Soy milk
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Black beans
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Pumpkin seeds
The body typically absorbs only 30% to 40% of dietary magnesium, making dietary overdose unlikely. (7)
Magnesium also has a laxative effect which helps to expel excess magnesium. Regular bowel movements play a key role in eliminating excess magnesium from the body, especially when using magnesium-containing medications like laxatives or antacids. (8)
Understanding Magnesium Overdose and Excess Magnesium
Magnesium overdose, or hypermagnesemia, happens when there is too much magnesium in the bloodstream.
This condition is most often linked to taking high doses of magnesium supplements or using magnesium-containing medications.
Individuals with certain health conditions or impaired kidney function have a higher risk for magnesium toxicity and should be especially cautious with supplementation.
Healthy kidneys usually filter out excess magnesium, but when kidney function is compromised, magnesium absorption can build up to dangerous levels. (9, 10)
The symptoms of magnesium toxicity can range from mild to severe cases.
Symptoms of Magnesium Toxicity
Early signs of too much magnesium may include:
- Diarrhea
- Nausea
- Abdominal cramps
- Muscle weakness.
As magnesium levels rise, more serious effects can develop, such as:
- Low blood pressure
- Facial flushing.
- Lethargy.
Severe symptoms of magnesium overdose or severe hypermagnesemia can cause:
- Irregular heartbeat
- Difficulty breathing
- Extreme low blood pressure.
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Severe toxicity can also result in confusion, loss of reflexes, coma, and cardiac arrest.
The first treatment for magnesium toxicity is to stop taking supplements or medicines containing magnesium.
Upper Limit for Magnesium Supplements
Due to the danger of excess magnesium, the NIH Office of Dietary Supplements recommends that the most an adult should ingest from supplements alone is 350 mg daily. This is the Upper Limit for Magnesium from supplements, and doesn’t include other sources. (11, 12)
As you can see, the effects of magnesium toxicity can range from mild digestive issues to life-threatening complications as blood levels rise.
Life-threatening magnesium toxicity typically occurs at very high doses, such as 5,000 mg per day, often from misuse of magnesium-based laxatives or antacids. A person with severe hypermagnesemia is often treated with calcium gluconate through an intravenous drip.
These complications highlight the importance of being cautious with magnesium supplementation and recognizing the signs of too much magnesium.
Note that high doses of magnesium can interfere with the absorption of certain antibiotics, bisphosphonates, and blood pressure medications.
Always consult a healthcare provider before starting or increasing your magnesium intake, especially if you have any underlying health conditions or are taking other supplements or medications. Prompt recognition and treatment of magnesium toxicity are crucial to prevent severe complications.
Special Considerations
Certain groups of people need to take extra care when it comes to magnesium supplements and the risk of magnesium overdose.
Pregnant women, for example, should always consult their healthcare provider before taking magnesium supplements, as high doses can increase the risk of complications during pregnancy and childbirth.
As I mentioned, individuals with kidney disease or kidney failure also have risk factors, since their bodies may not be able to clear excess magnesium efficiently. For these individuals, close monitoring of magnesium levels and careful adjustment of supplement dosages are essential.
The Best Time to Take Magnesium
Magnesium supplements can be taken at any time during the day, provided you take them consistently to reap the benefits.
For some, taking them first thing in the morning is beneficial, for others, with their evening meal or before bed.
Depending on what you may be taking magnesium for, it may be more beneficial to take it shortly before bedtime, if you are seeking a natural sleep aid.
Learn more about “Best Time to Take Magnesium” here!
Magnesium as a Sleep Aid: Study Conclusions
Find out what clinical trials say about the impact of magnesium on sleep...
"Supplementation of magnesium appears to improve subjective measures of insomnia such as ISI score, sleep efficiency, sleep time and sleep onset latency... in elderly people." - 2012 clinical trial. (13)
"The results of this study point out that persons with mental and physical stress can benefit from a daily intake of magnesium. This might... prevent restlessness, irritability, lack of concentration, sleep disorder or depression." - 2016 study of 90-day magnesium supplementation on heart rate variability. (14)
Best Magnesium Supplement Sleep Aid
If you're looking to take a magnesium supplement for sleep issues or potential leg cramps during the night, we recommend Performance Lab Sleep.
With a modest 100mg of magnesium, it also contains natural melatonin from Montmorency tart cherries, lemon balm for anti-stress, and L-Tryptophan. All designed to help you gain a better night's sleep.
The level of magnesium included here is well underneath the Upper Limit suggested by experts.
An immediate change in quality and consistency of sleep. I highly recommend it.Stephanie B
The Bottom Line
Magnesium is one of the most essential nutrients for multiple bodily functions and overall health. While it is generally a safe supplement to take when following the dosage guidelines, you may be at risk of overdosing or experiencing side effects if you take high doses. If that happens, seek medical attention.
Be sure to check the dosage of any supplement you take and avoid taking super high doses. Stick to the recommended maximum intake of 350mg per day or less to avoid any potential side effects or risk of overdose.
Looking for a natural sleep aid containing magnesium? Performance Lab Sleep has got you covered, containing a combination of magnesium, melatonin, and L-tryptophan to help relax muscles and enhance nightly cell renewal for revitalized next-day performance!
We also have a dedicated magnesium supplement, Performance Lab Magnesium, which provides 137mg of magnesium. Again, well under the Upper Limit.
References
- National Institutes of Health, Office of Dietary Supplements. “Magnesium: Fact Sheet for Health Professionals.” https://ods.od.nih.gov/factsheets/Magnesium-HealthProfessional/.
- Harvard T.H. Chan School of Public Health. “Magnesium.” The Nutrition Source. https://nutritionsource.hsph.harvard.edu/magnesium/.
- Missouri Poison Center. “Can You Overdose on Magnesium and What Are the Symptoms?” https://missouripoisoncenter.org/magnesium-overdose/#.
- DiNicolantonio, J. J., et al. “Magnesium and Cardiovascular Disease.” Open Heart, 2018. Rude, R. K. “Magnesium Deficiency: A Cause of Heterogeneous Disease.” Journal of Bone and Mineral Research, 1998.
- Volpe, Stella Lucia. “Magnesium in Disease Prevention and Overall Health.” Advances in Nutrition 4, no. 3 (2013): 378S–383S. https://doi.org/10.3945/an.112.003483.
- National Institutes of Health, Office of Dietary Supplements. “Magnesium: Fact Sheet for Consumers.” https://ods.od.nih.gov/factsheets/magnesium-consumer/.
- Jahnen-Dechent, W., and M. Ketteler. “Magnesium Basics.” Clinical Kidney Journal 5, suppl. 1 (2012): i3–i14. https://doi.org/10.1093/ndtplus/sfr163.
- Missouri Poison Center. “Can You Overdose on Magnesium and What Are the Symptoms?” https://missouripoisoncenter.org/magnesium-overdose/#.
- Cascella, Marco, and Saira Vaqar. “Hypermagnesemia.” In StatPearls. Treasure Island, FL: StatPearls Publishing, 2025. https://www.ncbi.nlm.nih.gov/books/NBK549811/.
- Healthline. “Can You Have Too Much Magnesium?” https://www.healthline.com/health/food-nutrition/magnesium-overdose-whats-the-likelihood.
- National Institutes of Health, Office of Dietary Supplements. “Magnesium: Fact Sheet for Consumers.” https://ods.od.nih.gov/factsheets/magnesium-consumer/.
- Harvard T.H. Chan School of Public Health. “Magnesium.” The Nutrition Source. https://nutritionsource.hsph.harvard.edu/magnesium/.
- Abbasi, Bahram, et al. “The Effect of Magnesium Supplementation on Primary Insomnia in the Elderly: A Double-Blind Placebo-Controlled Clinical Trial.” Journal of Research in Medical Sciences 17, no. 12 (2012): 1161–1169.
- Wienecke, E., and C. Nolden. “Langzeit-HRV-Analyse zeigt Stressreduktion durch Magnesiumzufuhr [Long-Term HRV Analysis Shows Stress Reduction by Magnesium Intake].” MMW Fortschritte der Medizin 158, suppl. 6 (2016): 12–16.
