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Magnesium Side Effects and Overdose

Magnesium has long been lauded for its multiple health benefits. From supporting bone health to improving nerve function, magnesium supplements can play a vital role in maintaining our well-being. However, just like any other supplement, it also comes with potential side effects, especially when taken excessively. Let's delve into the potential side effects of supplementing with magnesium and how to manage them.

An overdose of magnesium or too much magnesium in the body known as hypermagnesemia is often found in people with kidney disorders and can occur when medication such as laxatives containing magnesium are taken. It is also possible for someone just to take too much magnesium and while the magnesium itself is not really life-threatening the side effects can be annoying.

Unless your kidney function is comprised, it is difficult to overdose on magnesium unless you’re taking supplements far beyond the recommended daily doses. For the majority of the population, taking some magnesium will benefit their health.


What happens when there is too much magnesium in your body?

For people with kidney issues or the inability to process magnesium properly, excessive amounts of magnesium can occur inside the human body and often the symptoms or side effects of this are quite mild.

Less dangerous but very uncomfortable side effects include diarrhea, nausea and vomiting. These symptoms can pass once the magnesium levels normalise.  In more severe cases of hypermagnesemia muscle weakness occurs and people find is difficult to do simple things such as lifting, carrying and even standing up.

Another side-effect of too much magnesium that is uncomfortable that can lead to further problems is urine retention. This and the symptoms above are fairly clear to identify and may simply pass. However, there are some side-effects that will need medical attention because they are of greater concern.

Because magnesium controls many muscles and plays a role in the how the works an irregular heartbeat and low blood pressure can occur in some people. People with kidney disorders are especially at risk of these more concerning side effects. In worse case scenarios cardiac arrest can occur as a result of a magnesium overdose.

In all cases of magnesium overdose the effects of the magnesium can be quickly reversed. Getting medical help and having calcium gluconate delivered intravenously is the quickest and most effective way to reverse the magnesium side effects. However, in more severe cases magnesium may need be flushed from the system and dialysis may be the only option.


Potential Side Effects of Magnesium Supplements

While magnesium is a key nutrient, excessive supplementation can lead to several adverse effects. Here are some potential side effects to keep an eye on:

  1. Gastrointestinal Issues: One of the most common side effects is gastrointestinal discomfort. Overdosing on magnesium supplements can lead to diarrhea, nausea, and abdominal cramping. This is primarily because unabsorbed magnesium in the gut attracts water, causing these symptoms.

  2. Electrolyte Imbalance: Magnesium plays a crucial role in balancing the electrolytes in our body. However, excessive intake can disrupt this balance, leading to symptoms like fatigue, muscle weakness, and even irregular heartbeats.

  3. Kidney Problems: If you have kidney disease, you need to be extra cautious with magnesium supplements. The kidneys regulate magnesium in the body, and impairment can lead to magnesium build-up, causing further health complications.

  4. Medication Interactions: Magnesium supplements can interact with certain medications, including antibiotics, muscle relaxants, and blood pressure medicines. It's always advised to consult a healthcare provider before starting any new supplement.


In summary, overall, magnesium is considered safe and an overdose is extremely unlikely through a normal and healthy diet. Those with disorders such as hypothyroidism, Addison’s disease, or gastrointestinal disorders are at higher risk than most people. Doctors will advise people with such conditions about the effects of magnesium. The only other people at risk from a mild overdose of magnesium are those who consume a large number of supplements that contain magnesium.

Remember magnesium is vital for a healthy body. Focus on a healthy diet that includes foods with high levels of magnesium and a quality supplement if you find yourself suffering from any of the common magnesium deficiency symptoms.

Magnesium Information

For everything you need to know about magnesium and magnesium supplements, check out our comprehensive information page here.

Magnesium Information


We’ve created a magnesium supplement with a combination of three types of highly absorbable magnesium at a therapeutic dose. Our magnesium comes as an easy to mix, great tasting powder to ensure optimal absorption. To learn more about our magnesium, check out the product page here.

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Ron Goedeke MD, BSc Hons MBChB, FNZCAM

Dr. Ron Goedeke, an expert in the domain of functional medicine, dedicates his practice to uncovering the root causes of health issues by focusing on nutrition and supplement-based healing and health optimisation strategies. An esteemed founding member of the New Zealand College of Appearance Medicine, Dr. Goedeke's professional journey has always been aligned with cutting-edge health concepts.

Having been actively involved with the American Academy of Anti-Aging Medicine since 1999, he brings over two decades of knowledge and experience in the field of anti-aging medicine, making him an eminent figure in this evolving realm of healthcare. Throughout his career, Dr. Goedeke has been steadfast in his commitment to leverage appropriate nutritional guidance and supplementation to encourage optimal health.

This has allowed him to ascend as one of the most trusted authorities in the arena of nutritional medicine in New Zealand. His expertise in the intricate relationship between diet, nutritional supplements, and overall health forms the backbone of his treatment approach, allowing patients to benefit from a balanced and sustainable pathway to improved wellbeing.

The information provided is for educational purposes only and does not constitute medical advice. Always seek the advice of your physician or qualified healthcare provider with any questions or concerns about your health. Never disregard or delay seeking medical advice because of something you have heard or read on this website

Last update 13th April 2023

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