Magnesium deficiency: 10 common signs and symptoms

Some supplements are more confusing than others. It’s clear what you’re getting with a bottle of fish oil. And then there are those like vitamin D, which has two forms. If you thought that was confusing, enter magnesium with its seven different forms.

It’s no wonder that a study from 2005-2006 found that 48% of Americans are not hitting their recommended intake through food, though true magnesium deficiency or hypomagnesemia affects less than 2% of the population (Rosanoff, 2012; Guerrera, 2009).

But even if many of us are skirting the line of a clinical magnesium deficiency, it’s not to be taken lightly. Magnesium is both a mineral and an electrolyte that’s essential for our bodies to function. It plays a key role in keeping our heartbeat steady, regulating our blood pressure, and building and maintaining strong bones.

And if that isn’t enough to convince you to pay more attention to this tiny-but-mighty mineral, magnesium is also required for proper muscle and nerve function, energy production, DNA replication, and RNA synthesis.

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Hypomagnesemia, which is defined as serum magnesium, the amount present in your blood at the time of testing, being less than 1.8 mg/dL, is rare. But too many of us in the United States aren’t getting enough magnesium and are flirting with the line of deficiency.

It’s difficult to get a deficiency, and all too easy to be misdiagnosed as symptoms don’t become obvious until your magnesium levels are extremely low. And while a diet rich in healthy foods can generally meet your daily recommended intake, that’s not always enough to prevent a problem.

People suffering from certain health problems have an increased risk of magnesium deficiency. Digestive disorders, such as celiac disease, can increase gastrointestinal loss of the crucial mineral and limit magnesium absorption. 

Type 2 diabetes, refeeding syndrome, hungry bone syndrome, and genetic kidney problems also increase your risk of developing hypomagnesemia (although some of these are very rare) (Barbagallo, 2015).

Magnesium deficiency can be hard to diagnose. We already mentioned that some of the signs don’t appear until your low magnesium levels are critical. Another hurdle patients face is getting to the root cause with their healthcare practitioners.

Symptoms of magnesium deficiency tend to be nonspecific, so medical professionals may suspect other conditions or deficiencies. But if you know the signs and symptoms, you can better identify when you should seek out medical help and advocate for yourself in-office.

1. Loss of appetite

This is generally the first sign of hypomagnesemia. This is one of those nonspecific symptoms that can be hard to pin down, and it can come together with the next point on our list.

2. Nausea or vomiting

Another of the nonspecific magnesium deficiency symptoms is nausea or vomiting. It might seem like you ate something bad. Note what you’re feeling so you can accurately report to your healthcare professional, but keep an eye out for other symptoms that can be paired together to shed light on what’s going on.

3. Fatigue

Everyone feels fatigued from time to time. But if you’re feeling persistent fatigue that doesn’t get better with adequate rest and quality sleep, it’s time to take notes and see a professional. It’s worth noting, though, that fatigue isn’t enough to diagnose you since it’s such a nonspecific symptom of low magnesium levels.

4. Weakness

You’ll likely pair fatigue with weakness. Since this mineral plays a crucial role in proper muscle functioning—more on that in a second—an inadequate magnesium intake is likely to cause myasthenia, the fancy name for muscle weakness (Caddell, 2001).

This happens because magnesium deficiency is associated with a drop in potassium levels in muscle cells, also called hypokalemia. Scientists believe it’s this loss of potassium that causes muscle weakness (Huang, 2007).

5. Muscle spasms and cramps

With the rise of workout culture, more people are aware that muscle cramps are a sign of magnesium deficiency. Magnesium plays a crucial role in helping muscles relax and regulating muscle contractions.

In fact, you might have heard about or tried an Epsom salt bath after an intense gym session, which is one form of this important mineral: magnesium sulfate. But a deficiency can cause physical effects far beyond cramping, like tremors and even seizures. 

Unfortunately, for older adults experiencing cramping, getting rid of the muscular discomfort isn’t as easy as supplementing with magnesium even though studies show the mineral can help relieve cramps and twitches in other groups of people that are deficient (Garrison, 2012).

Magnesium deficiency can also cause a secondary deficiency, hypocalcemia, or lack of calcium, which also causes muscle spasms and cramps. So truly getting rid of them likely requires the correction of both conditions.

6. High blood pressure

Many studies that shape what we know about blood pressure and low levels of magnesium are done in rats, not people. These studies indicate that magnesium deficiency contributes to high blood pressure, which may up the odds of developing heart disease. 

Observational studies of humans have found that lack of magnesium through dietary intake ups the odds of higher blood pressure. Luckily, the connection doesn’t just go one way. A meta-analysis of studies on magnesium found that supplements of this important mineral can successfully lower blood pressure (Zhang, 2016).

7. Irregular heartbeat

Arrhythmia, or an irregular heartbeat, is serious. It can cause chest pain, lightheadedness, shortness of breath, or even fainting. And these abnormal heart rhythms can be caused by low levels of magnesium. It’s believed this is another symptom that has to do with magnesium deficiency causing secondary deficiencies, in this case, potassium.

8. Seizures

The same mechanism that causes muscle cramps and spasms is also behind this very serious sign of magnesium deficiency. Its believed that a lack of magnesium irritates the nervous system through the way it affects calcium in cells.

9. Personality changes

You never feel like yourself when you’re sick, but if your magnesium intake isn’t cutting it, you may not act like yourself either.

Personality changes like apathy, marked by numbness and lack of emotion, can occur and with a low enough magnesium status, even delirium, and coma. And a meta-analysis found an association between low magnesium levels and an increased risk of depression (Cheungpasitporn, 2015; Pham, 2014).

10. Osteoporosis

You likely know that vitamins are involved in your risk factor for developing osteoporosis—specifically vitamins D and K—along with old age. Magnesium-deficient people are also at a higher risk of developing the condition that weakens bones and puts people at a higher risk of fractures.

But getting enough magnesium can help in more ways than one. Adequate magnesium intake is associated with higher bone mineral density and can prevent hypocalcemia. Though magnesium or lack thereof can act directly on your bones, it also affects their strength by causing a lack of calcium (Farsinejad-Marj, 2015; Castiglioni, 2013).

Of course, these are just some symptoms that may occur with a magnesium deficiency. Each person may actually experience all, some, or none of these symptoms, even in the presence of a deficiency.

This is where those nonspecific symptoms come in. Since it can be hard to pin down what’s causing general symptoms like fatigue and loss of appetite, your healthcare practitioner will use a variety of methods to diagnose you. They’ll likely take into account not just your symptoms but also your medical history, a physical exam, and a blood test. Although checking your blood magnesium level doesn’t give a medical professional the whole picture—much of your magnesium is stored in your bones and soft tissues—it can help form a picture of magnesium deficiency. Hypomagnesemia also causes other deficiencies, like hypokalemia (low potassium) and hypocalcemia (low calcium), that they’ll likely test for as well.

Luckily, getting our levels of magnesium back on track isn’t all that difficult. But there are some exceptions where it can take longer, like if you have diarrhea or other malabsorption issues in your gut.

But there are some side effects to magnesium supplements, the most common of which is loose stools or diarrhea. This side effect can be especially pronounced if you take magnesium citrate, which is known for increasing water in the intestines.

Plan meals to make sure you’re incorporating dietary magnesium if you find you’re sensitive to taking oral magnesium. People with certain health conditions, such as kidney diseases, or those taking medications like bisphosphonates, antibiotics, diuretics, and proton pump inhibitors, need to talk to their healthcare practitioners before taking dietary supplements.

Many magnesium-rich foods—such as leafy greens, whole grains, avocado, and cashews—are common and offer other health benefits along with this important mineral. If a medical professional does put you on a magnesium protocol, follow it. Hypermagnesemia, or having too much magnesium, can also be dangerous.

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Current version

October 23, 2019

Written by

Linnea Zielinski

Fact checked by

Mike Bohl, MD, MPH, ALM

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About the medical reviewer

Mike Bohl, MD, MPH, ALM

Dr. Mike is a licensed physician and a former Director, Medical Content & Education at Ro.