Written by Joanna Jan, MD | Reviewed by Katie E. Golden, MD
Published on April 14, 2022
Key takeaways:
Magnesium is a mineral that helps your body work properly. But your body can’t make magnesium on its own, so it’s important to get enough of it from your diet.
A low magnesium level, also called “hypomagnesemia,” is a blood magnesium below 1.7 mg/dL. There are several different causes, like poor dietary intake or loss of magnesium from the urinary or digestive tract.
Severe magnesium deficiency can cause problems with the function of your nervous system and heart. It can lead to things like muscle spasms, seizures, or heart arrhythmias.
Oral or intravenous magnesium can supplement a low magnesium level. But it’s important to find and address the underlying cause.
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Magnesium is a mineral that the body uses for many processes in every organ and cell. We often hear more about other electrolytes — like sodium, potassium, and calcium — and less about magnesium. But like these other electrolytes, magnesium plays a critical role in our metabolism and overall functioning. It’s especially important for the nervous system and the heart’s electrical conduction system.
Low or deficient magnesium levels, also called “hypomagnesemia,” can cause a variety of problems. Some are more serious than others. Here we’ll discuss the symptoms, causes, diagnosis, and treatment of this condition.
Symptoms of magnesium deficiency
Low magnesium levels can cause a range of symptoms in different parts of the body. Many of the symptoms involve problems with the electrical conduction in your nervous system and heart.
Some of the symptoms of hypomagnesemia may include:
Weakness and fatigue
Tremors or muscle twitching
Muscle cramping
Heart palpitations or heart arrhythmias
Numbness
Seizures
Confusion or mood changes
In many cases, low magnesium is associated with low levels of other important electrolytes. Low levels of calcium and potassium are especially common. That’s because low levels of these electrolytes share common causes.
Causes of magnesium deficiency
There are several causes of low magnesium levels:
Not enough magnesium in the diet
This can happen if you’re malnourished or don’t eat enough foods that have magnesium. The good news is that there are a lot of healthy foods that are rich in magnesium (check out the list below).
Low magnesium intake is also very common in people with alcohol use disorder.
Poor magnesium absorption in the digestive tract
Some conditions lead to poor magnesium absorption from the diet. This can happen even if you eat enough magnesium in your diet. Examples include:
Celiac disease
Inflammatory bowel disease
Gastric bypass surgery
You can also lose magnesium through your digestive tract when you vomit or have diarrhea for any reason.
Loss of magnesium through the urinary tract
Some medications can cause you to lose more magnesium in your urine. These medications include:
Diuretics that treat high blood pressure and heart conditions, like hydrochlorothiazide
Antibiotics, like aminoglycosides
Chemotherapy medications, like cisplatin
Proton pump inhibitors, like pantoprazole
Conditions that cause you to urinate more can also lead to a big loss of magnesium. High blood sugar from diabetes is one common cause. And there are also inherited conditions that lead to hypomagnesemia through the urine. These include Bartter syndrome and Gitelman syndrome.
Shift of magnesium from the blood into the cells
Certain conditions can cause magnesium to move out of the blood and into the cells, leading to low magnesium levels in the blood. This makes the magnesium less accessible for other organs. For example, inflammation of the pancreas (pancreatitis) can cause this shift of magnesium. Advanced pregnancy can also cause this in some cases.
Other losses
You can also have a low level of magnesium from excessive sweating or burn injuries to large portions of the body.
Diagnosis of magnesium deficiency
To diagnose hypomagnesemia, a healthcare provider checks the level of magnesium in your blood. A normal magnesium level is 1.7 to 2.2 mg/dL. So a level at or below 1.6 mg/dL is below normal. But most people don’t experience any symptoms until the magnesium level is below 1.2 mg/dL.
Once a provider diagnoses hypomagnesemia, they will try to find the underlying cause. Blood tests might show infection, other electrolyte imbalances, and abnormal blood sugar levels. And your provider may order urine tests to see if you’re losing magnesium through your urine.
Treatment for hypomagnesemia
Treatment for low magnesium levels includes oral (by mouth) magnesium supplements (magnesium oxide pills). If your levels are especially low or cause symptoms, intravenous (IV) magnesium is a better option.
In addition to treating the low level, it’s important to figure out the reason for the low magnesium and treat the underlying condition.
If your magnesium is low because you aren’t getting enough magnesium in your diet, try to eat more of the following foods that have lots of magnesium:
Nuts and nut butters — especially almonds, peanuts, and cashews
Spinach
Grains, like rice and whole-wheat breads and cereals
Black beans and edamame
Soymilk
Yogurt
Potatoes
A serving of each of the above foods contains 40 to 80 mg of magnesium. Experts recommend that adults consume 400 mg of magnesium every day. This may be easier than you think — a small serving of pumpkin or chia seeds contains up to 150 mg of magnesium!
It’s also important to recheck your magnesium level and continue supplementing for several days after your level returns to normal. This is so you restore your magnesium levels in your blood as well as your cells, which can take a bit longer.
Depending on the cause of your low magnesium level, there are also medications — aldosterone antagonists — that can help decrease the loss of magnesium in the urine.
Your healthcare provider can help you figure out the underlying cause and decide how to best manage your low magnesium level.
The bottom line
Magnesium is an important mineral in the body. It plays an especially important role in the electrical conduction pathways in the nervous system and heart. A low magnesium level can have many different causes. And it’s important to identify and address the underlying reason in addition to treating the low level with oral or IV supplementation. Luckily, many causes of low magnesium are easily treated. And you can often fix the magnesium level by taking oral supplements and increasing magnesium-rich foods in your diet.
Written by:
Joanna Jan, MD
Joanna Jan, MD, is board-certified in internal medicine and licensed to practice medicine in the state of Pennsylvania. In 2017, she received her board certification from the American Board of Internal Medicine.
Edited by:
Katie E. Golden, MD
Katie E. Golden, MD, is a board-certified emergency medicine physician and a medical editor at GoodRx.
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