9 Low Magnesium Symptoms: Short-Term and Mild or Long-Term

Magnesium is an essential mineral vital for regulating your heart rhythm; muscle, nerve, and brain functions; and energy levels. Low magnesium can occur when you don't get enough magnesium in your diet, your body doesn't absorb it well, or you excrete too much.

People with certain medical conditions such as diabetes, gastrointestinal disorders, and alcohol use disorders, as well as older adults are at higher risk of deficiency. While you may not have symptoms initially, early symptoms include:

• Fatigue
• Muscle weakness
• Poor appetite
• Nausea

This article reviews low magnesium symptoms, how they progress over time, the daily requirements of magnesium, how to know if you are getting enough, and what to do if you need more magnesium.

Low Magnesium May Not Immediately Cause Symptoms

An adult body stores about 25 grams (g) of magnesium—60% in your bones and 40% in your cells. Less than 1% of magnesium in the body stays in the serum (liquid portion of the blood).

Low magnesium may not cause symptoms initially because your bloodstream borrows excess magnesium from your cells or bones. Your body can perform vital functions until the cells and bones run out of extra magnesium. Symptoms arise when there is nothing left to tap into.

Low Magnesium Symptoms That May Occur Over Time

The timing and severity of symptoms depend on the degree and rate of magnesium depletion. You or a healthcare provider may overlook a magnesium deficiency, delaying a diagnosis because of subtle symptoms like fatigue. Here are some examples of low magnesium symptoms:

• Muscle weakness and fatigue
• Loss of appetite
• Nausea
• Muscle spasms
• Mood or personality changes 
• Tingling
• Stiffness
• Insomnia
• Abnormal heartbeat
  

Am I Getting Enough Magnesium?

Studies show that about 50% of the U.S. population does not get enough magnesium in their diet. This may be because they do not eat enough foods containing magnesium or because minerals such as magnesium have been depleted in the soil or by food processing. 

Can You Test for Low Magnesium on Your Own?

At-home vitamin-deficiency tests are available. The self-tests typically involve a finger-prick blood test where you can collect a sample at home and send it to the distributor's lab for analysis. You usually get results a few days after the lab receives the sample. 

Sharing the results with a healthcare provider is vital because magnesium levels within the normal range do not necessarily mean you have enough magnesium. These tests do not provide information about magnesium stores in the body. 

The same applies to a serum magnesium blood test ordered by a healthcare provider. Expected values vary between laboratories but are typically around 1.5 to 2.4 milligrams per deciliter (mg/dL). Symptoms usually occur when serum magnesium levels fall below 1.2 mg/dL. 

But having symptoms or having a magnesium level at the lower end of the normal range could indicate a possible deficiency. The provider may order other, more specialized tests, including the following:

• Red blood cell (RBC) magnesium test: This test reflects magnesium in the cells, not just the blood.  
• 24-hour urine test: This test measures how much magnesium your kidneys excrete.
• Ionized magnesium: This test measures free, unbound magnesium ions in the blood. A serum test measures both bound and free magnesium ions and is more common for those who are critically ill.
• Magnesium loading test: In this test, a healthcare provider gives you intravenous or oral magnesium and watches how you absorb and excrete it. 
• Hair mineral analysis: This test evaluates mineral deficiencies and heavy metal toxicity in the hair.

Risks of Untreated Symptoms of Low Magnesium 

Left untreated, low magnesium levels can lead to the onset or worsening of the following health conditions:

• Seizures
• Heart rhythm disturbances
• High blood pressure (hypertension)
• Osteoporosis
• Migraines
• Type 2 diabetes 
• Coronary artery disease
• Stroke
• Congestive heart failure (CHF)
• Asthma
• Kidney stones
• High cholesterol or triglycerides
• Chronic obstructive pulmonary disorder (COPD)
• Mental health disorders

What to Do With a Magnesium Deficiency 

Depending on your level of magnesium deficiency, underlying health conditions, and the medications you take, your healthcare provider may recommend dietary changes or supplementation.

Dietary Changes

Dietary changes may involve increasing magnesium-rich foods and limiting sugar, saturated fat, sodium, and alcohol.

While this is not an exhaustive list, magnesium-rich foods include:

Some health conditions and medicines can increase your risk of low magnesium by:

• Decreasing your appetite
• Causing poor magnesium absorption 
• Increasing magnesium excretion (peeing or pooping it out) 

For example, older adults, critically ill people, and those with alcohol use disorder, gastrointestinal problems, and diabetes are at higher risk of deficiency. Examples of health conditions and medications that can contribute to lower magnesium levels include:

• Alcohol use disorder
• Gastrointestinal conditions (e.g., celiac disease, cystic fibrosis, diarrhea, inflammatory bowel disease)
• Diabetes and other endocrine or metabolic disorders
• Kidney disease
• Starvation
• Vitamin D deficiency
• Some medications (e.g., diuretics, proton pump inhibitors, certain antibiotics, immunosuppressants, and chemotherapy drugs)

This means that dietary changes or supplements may not fix low magnesium, especially if you have an underlying condition or take a medication causing the deficiency. 

Magnesium Supplementation

If you need oral magnesium supplements, follow a healthcare provider's guidance regarding the dosage and the amount. Even though magnesium supplements are natural, they can cause side effects or interact with other medications or supplements. 

It is possible to take too much magnesium. Also, medications such as antacids and laxatives contain a significant amount of magnesium and can cause your daily dosage to be too high.

If your healthcare providers need to increase your magnesium levels quickly, they will offer it to you intravenously (IV) in a hospital setting. For example, providers commonly give IV magnesium to pregnant people with preeclampsia to lower their blood pressure. 

Symptoms of Too Much Magnesium 

Getting too much magnesium from food is unlikely unless a health condition prevents your kidneys from flushing it out of the body. But extremely high doses of magnesium (more than 5,000 mg/day) can be toxic and cause the following:

• Low blood pressure or low heart rate
• Muscle weakness 
• Fatigue
• Nausea or vomiting
• Facial flushing (redness)
• Urinary retention (not able to pee)
• Paralysis (with very high levels)
• Cardiac arrest

Summary

Magnesium is an essential mineral that helps your body function. Low levels may not cause symptoms initially as the body borrows stored magnesium cells. But, eventually, you may experience fatigue, poor appetite, nausea, muscle spasms, mood changes, tingling, stiffness, insomnia, or an abnormal heartbeat.

Most people get enough magnesium in their diet. But, some people may need supplementation. Taking too much magnesium can also cause stomach upset or magnesium toxicity, so always consult a healthcare provider before starting a new supplement.