Signs and Symptoms of Too Much Magnesium

Magnesium overdose is often a result of excessive magnesium from supplements rather than food sources.
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Magnesium overdose is often a result of excessive magnesium from supplements rather than food sources, but it's still important to be aware of its potential side effects. Even though it is a highly beneficial mineral, too much of it may cause adverse reactions.

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Signs of Too Much Magnesium

The recommended daily dose for supplementary magnesium is 350 milligrams, and this applies to ages 9 upward through to adulthood. Not to be confused with manganese, magnesium is a mineral found in a large variety of foods, and it's perfectly safe to be consumed without fear of magnesium overdose, as the Linus Pauling Institute notes.


Magnesium poisoning has never been found to originate from food sources. Instead, it is magnesium supplements that facilitate overdosing.

Those with impaired kidney function are at an even greater risk of magnesium overdose. This is because when the kidneys are functioning as they are meant to, they will remove excess magnesium from the body via urine. If your kidneys are impaired, this process either cannot occur or happens with far less efficiency, resulting in a buildup of the mineral.

Impaired kidney function doesn't only lead to magnesium overdose — it can also contribute to magnesium deficiency. According to of Australia, certain illnesses, such as Crohn's disease, celiac disease and Type 2 diabetes, all affect the body's ability to absorb and store this mineral. In these instances, a health care professional may recommend magnesium supplements, but it's important to be aware of the symptoms of overdose that can arise from popping pills.


According to the Linus Pauling Institute, side effects of too much magnesium in the body include:

  • Diarrhea: Magnesium supplements are often used therapeutically as a laxative to treat constipation that may arise from a variety of conditions. However, an excess of magnesium will result in diarrhea. This is one of the first symptoms of an overdose.
  • Hypertension: A fall in blood pressure, otherwise known as hypotension, can also be an early sign of magnesium poisoning.


  • Lethargy: Energy levels may start to drop if there is excess magnesium present in the body, resulting in the feeling of excess tiredness and weakness.
  • Confusion: Cognitive processes may be slower and it may be increasingly difficult to focus your mind when the body is struggling with a magnesium overdose.
  • Irregular heartbeat: Magnesium poisoning can lead to a disturbance of the cardiac rhythm, which in turn, can have harmful effects on cardiovascular function.


  • Weakness: In addition to the lethargy experienced, your muscles may also begin to physically deteriorate and weaken as magnesium is a mineral directly linked to the production of new proteins in the body. Without these proteins, muscle strength cannot be maintained.
  • Breathlessness: Inability to catch your breath is another sign of magnesium poisoning, which can be highly debilitating when paired with lethargy and weakness.

Additionally, the National Institutes of Health warns that nausea, abdominal cramping and vomiting are all signs of magnesium poisoning.


In exceptional cases, untreated magnesium poisoning can lead to cardiac arrest and may prove fatal. If you experience any of the above symptoms, it is recommended to contact your health care provider for advice, especially if you take magnesium supplements and/or have kidney problems.

Read more: Everything You Should Know About Vitamins and Supplements

Sources of Magnesium

Despite the fact that food sources of magnesium have never been found to cause poisoning, it may still be important to be aware of the amount entering your diet from the types of food you are consuming.

If you're struggling with an overdose of this mineral following treatment with supplements, it may be wise to reduce the amount of magnesium-rich foods in your diet. In contrast, if you are struggling with a deficiency, being aware of magnesium-rich foods will aid you in restoring your body's adequate levels.

Below is a list of some of the foods that possess the highest content, alongside the milligram count of magnesium per serving for each, as provided by the National Institutes of Health:

  • Almonds: 80 milligrams
  • Spinach: 73 milligrams
  • Black beans: 60 milligrams
  • Cashews: 74 milligrams
  • Peanut butter: 49 milligrams
  • Bread (2 slices): 46 milligrams
  • Avocado: 44 milligrams
  • Baked potato: 43 milligrams
  • Brown rice: 42 milligrams
  • Oatmeal: 36 milligram
  • Peanuts 63 milligrams

The Cleveland Clinic also lists the following as magnesium-rich foods:

  • Dark chocolate: 50 milligrams
  • Salmon: 26 milligrams
  • Halibut: 24 milligrams
  • Chicken breast: 22 milligrams

Generally speaking, some of the richest dietary sources of magnesium are greens, nuts, seeds, dry beans, whole grains and low-fat dairy products. The majority of your daily recommended amount of magnesium will come from your diet, and you don't need to worry about magnesium poisoning as this predominantly only occurs from supplementation.

Read more:How Soon Do You Feel the Benefits of Magnesium?

Benefits of Magnesium Supplements

According to the U.S. National Library of Medicine, magnesium is necessary for more than 300 biochemical reactions in the human body. It aids in the maintenance of nerve health and muscle function, keeps your bones strong, regulates heart rate and supports the immune system. In addition to this, it aids in the production of energy and proteins.

Magnesium supplements may benefit those struggling with osteoporosis due to the mineral's role in bone strength and protein production. A July 2013 review published in the journal Nutrients established that both excessive and low levels of magnesium can negatively affect bone strength, but if balance is maintained, then bone integrity will experience the greatest benefit. To maintain this exact dose, supplements are often used.

Another review published in the ​World Journal of Diabetes​ in August 2015 explored the link between magnesium and the development of Type 2 diabetes. As the researchers explain, it's already established that magnesium deficiency is common in patients with diabetes, but it isn't entirely clear if supplements are the best course of treatment to fix this.

The risk of magnesium overdose due to supplementation is a cause for hesitation, despite the link between magnesium deficiency and Type 2 diabetes as well as certain metabolic disorders. If you are concerned about your magnesium intake, contact your health care professional for advice before embarking on any magnesium supplementation. This is especially important if you are on certain medications, as interactions may occur.