7 Side effects when you take magnesium supplements

Magnesium, a vital mineral, is crucial to our overall health and well-being. It’s no wonder that magnesium supplements have gained popularity among those looking to boost their intake of this essential nutrient. 

In this blog, we’ll explore seven side effects of magnesium supplements. We aim to provide you with valuable information so that you can make informed decisions about your health. 

Many individuals who take magnesium supplements may not experience side effects, but it is important to note that potential side effects exist, particularly with high doses.

What is the most common form of magnesium supplement?

Magnesium comes in various forms, each suited to different health needs [1]. Here’s a quick guide to the most common types:

  • Magnesium citrate
  • Magnesium oxide
  • Magnesium glycinate
  • Magnesium malate

Choosing the right magnesium supplement can depend on your specific health concerns, so consider what you want to address before deciding. Always check with a healthcare provider, especially if you’re already taking other medications

Are there any negative side effects to taking magnesium?

While magnesium supplements offer a range of health benefits, from improving sleep to supporting bone health, they can also come with some side effects, especially if taken in high doses or without proper guidance. Here’s what you might experience:

1. Vomiting and nausea  

Dramatic side effects of taking magnesium supplements are associated with extreme dosage. When taken in high amounts, magnesium can cause vomiting and nausea, which is known to be magnesium toxicity or hypermagnesemia. 

Magnesium is an electrolyte that interacts with the body’s sodium, especially during digestion in the small intestine and colon. 

When taken in large doses, magnesium may interfere with your normal digestion, which may cause some abdominal discomfort or loose stools. However, vomiting and nausea symptoms are only linked to excessive magnesium consumption. 

Magnesium supplementation should not normally cause dramatic symptoms. You just have to check with your health professional every time you take new or unfamiliar supplements and follow the dosing guidelines.

Many people do not commonly experience vomiting and nausea as a side effect of taking magnesium supplements unless they are taken in a high amount. 

Also, pregnant women rarely experience magnesium overdose on a normal diet. However, there is a high risk of magnesium overdose for women in general who take magnesium supplements.

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2. Diarrhea and dehydration

Magnesium supplementation promotes the negative stimulation of bowel movements in some pregnant women, which may cause diarrhea, cramping pain, stomach and loss of appetite.

When diarrhea is not treated, there is a high risk of dehydration, which can be a serious side effect that affects the amount of amniotic fluid during pregnancy.

Hence, if a pregnant woman regularly takes magnesium supplements and has experienced diarrhea for two to three days, she needs to seek professional help immediately. 

3. Stomach pain

Another common side effect of taking magnesium supplements is abdominal pain along with nausea and vomiting, as mentioned earlier. Magnesium supplements may cause conditions similar to morning sickness. 

Stomach pain usually subsides within several hours of treatment; however, if it persists, you must notify your health provider immediately.

In case a pregnant woman encounters stomach pain after taking magnesium supplements, she needs to go to an emergency room immediately. Magnesium overdose is considered fatal when not treated promptly.

Photograph: Iakobchuk/Envato

4. Loss of reflexes 

Loss of deep tendon reflexes is another documented side effect of magnesium toxicity caused by too much magnesium consumption. 

Recognizing the signs and having immediate treatment by fluid administration with diuretics can prevent fatal cardiac arrhythmias and lower neuromuscular transmission, leading to respiratory failure [2]. 

5. Cardiac arrhythmias 

Magnesium toxicity can cause irregular heartbeat and cardiac arrest in certain people. While magnesium supplements are normally well tolerated, they can also cause some side effects on cardio.

Overdose of magnesium supplements can lead to a medical condition known as hypotension, which occurs when your blood pressure drops too low [3]. 

Generally, high blood pressure is damaging, but that does not mean having low blood pressure is good. When you have low blood pressure, you are at a high risk of impaired ability to regulate blood flow, which leads to dizziness or light-headedness. 

Some clinical studies have focused on magnesium sulfate’s ability to induce controlled hypotension and lower patients’ blood pressure before surgery [4]. 

The magnesium doses utilized were exponentially large, or about 40mg/kg, and were injected by IV; hence, they differ greatly from the conditions when taking oral dietary supplements.

In certain circumstances, long-term supplementation of high magnesium levels in the blood can lead to a slowed heart rate called bradycardia or irregular heartbeats. 

In rare cases, high levels of magnesium are only seen in healthcare settings as a form of therapy or through IV injections.

6. Drowsiness

One major reason people patronize magnesium supplements is that some forms of the mineral aid in inducing sleep, as magnesium glycinate is present in some supplements. It can also be a rejuvenating sleep aid to help you fall asleep and have high-quality restfulness.

However, not all of your time is sleeping time. One primary side effect of magnesium is it can cause drowsiness. Thus, it is better to take magnesium supplements at the end of the day or at night to prevent the midday magnesium slump.

7. Magnesium toxicity

Taking magnesium supplements can ultimately cause magnesium toxicity, which in turn may result in different side effects that are mentioned above, including depression, low blood pressure, vomiting, retention of urine and muscle weaknesses.

However, magnesium toxicity is, most of the time, unusual and generally linked to extreme amounts of supplementation or underlying impaired kidney function.

Magnesium toxicity can be diagnosed when the concentration of the mineral in your blood reaches around 1.74 to 2.61 millimoles per liter [5]. When this happens, you may notice some other symptoms, including:

  • Confusion
  • Depression
  • Flushing in the face
  • Low blood pressure
  • Muscle weakness
  • Lethargy
  • Retaining fluid
Photograph: nateemee/Envato

What is magnesium deficiency? 

Magnesium deficiency occurs when the body does not get all the necessary magnesium for optimal health. 

Health issues associated with magnesium deficiency are considered rare, but if you have low magnesium levels in the long term due to other health conditions, such as alcoholism or taking some medications, you may be at a higher risk.

Symptoms of magnesium deficiency

Some factors can increase one’s risk of developing magnesium deficiency, such as: 

  • Continuously eating a low-magnesium diet
  • Losing a high amount of magnesium because of urine and sweat, which may result from genetic disorders or drinking too much alcohol
  • Experiencing gastrointestinal disorders, such as Crohn’s disease, celiac disease or regional enteritis
  • Have parathyroid disorders and hyperaldosteronism
  • Suffering from type 2 diabetes
  • Pregnancy and lactation 
  • Being hospitalized
  • May come with older age 
  • Taking some medications, like proton pump inhibitors, diuretics, bisphosphonates and antibiotics

Having a long-term magnesium deficiency may affect the following: 

  • Bone density
  • Brain function
  • Digestive system
  • Nerve and muscle function

Causes of magnesium deficiency

Generally, it is rare to have magnesium deficiency if you’re healthy. However, you may develop one due to the following factors: 

  • Have a poor diet, particularly in elderly people or people who don’t have enough to eat
  • Suffering from type 2 diabetes
  • Have existing digestive problems like Crohn’s disease
  • Kidney problems
  • Long-term use of diuretics
  • Long-term vomiting or diarrhea
  • Taking medicines, like fluid tablets and medicines for ulcers or reflux 
  • Too much alcohol consumption
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Risk factors you need to take note

Although magnesium supplementation is usually safe, you must consult your doctor before taking it, most importantly if you have a medical condition. 

Magnesium supplements may be unsafe for people who take diuretics, heart medications or antibiotics [6].

People suffering from diabetes, intestinal disease, heart disease or kidney disease are not advised to take magnesium unless prescribed by their healthcare provider.

For people taking blood sugar-lowering medications, magnesium supplements can increase the body’s absorption of some anti-diabetic medications, like sulfonylurea drugs, which is a good thing. However, the anti-diabetic drug Metformin can cause low magnesium levels. 

For people taking blood pressure-lowering medications, magnesium supplements help in reducing blood pressure. However, people on blood pressure medications are not advised to take magnesium without consulting with their doctor first. 

For people with kidney problems, it is important to note that they are at a higher risk of experiencing adverse effects when taking magnesium supplements [7]. 

Drug interactions

Taking magnesium supplements can stimulate the rise of some drug interactions. Some medications can interact with magnesium supplements or affect the body’s magnesium levels [8], including the following: 

  • Oral bisphosphonates are intended for osteoporosis treatment, particularly alendronate (Fosamax). 
  • Diuretic medications, like furosemide (Lasix), may increase magnesium excretion and one’s risk of magnesium deficiency. 
  • Proton pump inhibitors, like esomeprazole magnesium (Nexium), used to treat acid reflux, can also increase the risk of magnesium deficiency. 
  • Taking magnesium supplements can also affect antibiotics, like tetracyclines, fluoroquinolones and nitrofurantoin, as they can reduce their absorption. 

Some other antibiotics are quinolone antibiotics, such as levofloxacin (Levaquin) and ciprofloxacin (Cipro), doxycycline (Vibramycin) and demeclocycline (Declomycin).

How to avoid side effects?

Managing magnesium supplement intake wisely can help you steer clear of side effects:

  • Begin with a low dose and gradually increase it. This allows your body to adjust without shock.
  • Opt for a form of magnesium that suits your body’s needs and tolerance. Magnesium glycinate, for example, is easier on the stomach than magnesium citrate.
  • Consuming magnesium supplements with meals can reduce stomach upset and nausea.
  • Drink plenty of water throughout the day to help mitigate any laxative effects.
  • If you’re on other medications, discuss potential interactions with your healthcare provider to ensure your magnesium supplement doesn’t interfere with their efficacy.
  • Pay attention to how your body reacts and adjust your dosage accordingly. If adverse effects persist, consult your healthcare provider for guidance.

Final takeaways

Magnesium supplements, while beneficial for many, can have various side effects. As with any supplement, it’s essential to approach their consumption with informed caution. Over-reliance or excessive intake can lead to various symptoms affecting one’s overall health.

It’s crucial to consult with a healthcare professional before starting or adjusting any magnesium regimen. Recognizing potential side effects and monitoring one’s body responses ensures that individuals reap the benefits of magnesium without adverse impacts.

Always prioritize a balanced approach, and remember that natural dietary sources are often the best way to meet our nutritional needs.


What are the most common side effects of taking magnesium supplements?

The most common side effects include diarrhea, abdominal cramping, and nausea. These often occur when magnesium is taken in high doses or on an empty stomach.

Are there any dangers in taking magnesium supplements?

While magnesium supplements can be beneficial when used appropriately, there are potential dangers associated with excessive intake, such as digestive discomfort, muscle weakness, and interference with certain medications.

Can magnesium supplements interact with other medications?

Yes, magnesium can interfere with the absorption and effectiveness of various medications, including antibiotics and bone density drugs. Always consult with your healthcare provider before starting magnesium supplements.

How can I reduce the risk of experiencing side effects from magnesium?

To minimize side effects, start with a low dose and gradually increase it. Taking magnesium with food can also help reduce stomach upset.

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