The Health Benefits of Magnesium Chloride

Supplement form of magnesium may improve blood pressure and diabetes

Bowl of spinach, pumpkin seeds, almonds, magnesium tablets, magnesium capsules, and magnesium powder

Verywell / Anastasiia Tretiak

Magnesium chloride, known by chemical formula MgCl2, is a type of salt used as a nutritional supplement. It is found naturally in seawater but is most readily harvested from the brine of salt lakes—such as the Great Salt Lake in northern Utah and the Dead Sea situated between Jordan and Israel—where the salt content may be as high as 50%.

Magnesium chloride is thought to improve health, in part by increasing magnesium levels in people with a known deficiency. It is one of several compounds used for this purpose, others of which include magnesium aspartate, magnesium citrate, magnesium gluconate, magnesium glycinate, magnesium lactate, magnesium malate, magnesium oxide, and magnesium sulfate.

Magnesium chloride supplements are commonly found in tablet and capsule forms. Magnesium chloride flakes can also be used for therapeutic baths and foot soaks.

Health Benefits

Magnesium chloride is primarily used to supplement your dietary intake of magnesium. While it doesn't "treat" conditions per se, it can help overcome magnesium deficiency and, by doing so, improve or restore certain physiological functions.

Benefits of magnesium oxide
Illustration by Brianna Gilmartin, Verywell​

Magnesium Deficiency

Magnesium is a nutrient vital to human health. It is responsible for more than 300 biochemical reactions in the body, including the regulation of blood sugar, blood pressure, and muscle and nerve function. It is also essential to the production of protein, bone mineral, and DNA.

Although magnesium deficiency is often subclinical (meaning without obvious symptoms), it can manifest with generalized or non-specific symptoms such as fatigue, weakness, depression, fasciculations (involuntary twitches), and arrhythmia (irregular heartbeat).

Chronic magnesium deficiencies are closely linked to a wide range of health concerns, including asthma, migraine, type 2 diabetes, metabolic syndrome, hypertension, atherosclerosis, osteoporosis, and colon cancer

Though magnesium deficiency is relatively uncommon in the United States, a 2012 study in Nutrition Reviews suggests that half of all Americans consume less than the recommended amount of magnesium from food each day.

There are certain substances and/or situations that are known to induce magnesium deficiency in otherwise healthy people. These include:

Magnesium chloride supplements can help overcome (or, at the very least, mitigate) magnesium deficiency and, by doing so, improve health and physiological function.

Given the range of illnesses that magnesium deficiency can cause, there are some who believe that magnesium supplements may not only prevent certain diseases but actively treat them as well. It is a controversial issue subject to ongoing debate.

Type 2 Diabetes

One such example is type 2 diabetes, in which early studies had suggested that magnesium supplements were able to increase insulin sensitivity and improve glucose control. The results led some to assume that magnesium supplements were somehow independently associated with glucose control.

A 2017 review in the journal Nutrition evaluated 12 clinical trials and concluded the magnesium supplement did, in fact, improve insulin resistance in people with type 2 diabetes—but only in those with underlying magnesium deficiency. There is no evidence of benefit outside of this group, and it is unknown what level of deficiency is needed to reap the benefits of magnesium supplementation.

High Blood Pressure

There is some evidence, albeit uncertain, that magnesium supplements can help lower blood pressure in people with hypertension.

According to a 2016 review of studies in Hypertension, 368 milligrams of magnesium per day over a period of three months reduced the systolic (upper) blood pressure by 2 mmHg and the diastolic (lower) blood pressure by 1.78 mmHg compared a placebo. Moreover, the effect appeared to improve month by month.

Despite the positive findings, it is unclear if the blood pressure will continue to improve to normal levels with extended treatment or simply taper off.

Moreover, it is unknown if supplementation would benefit otherwise healthy people given that the reviewed studies mostly involved those with cancer, severe infectious disease, active liver or kidney disease, or other severe illnesses. Further research is needed.

There is as of yet no evidence that magnesium supplements can prevent hypertension.

Athletic Performance

Magnesium is often incorporated into sports supplements under the presumption that it can help boost energy levels and athletic performance. Despite a plethora of anecdotal reports supporting such use, the current evidence remains conflicted.

A 2015 study in the Journal of the International Society of Sports Medicine reported that 13 athletes prescribed a one- or four-week "loading" dose of magnesium (300 milligrams per day) experienced a nominal 7.7% increase in bench press performance on the day immediately following the completion of treatment.

However, on day two, those give a four-week course of magnesium experienced a 32% drop in performance as opposed to those treated for one week, who had no change in performance.

Magnesium likely does contribute to athletic performance (especially in situations when electrolytes are depleted through sweat). However, given the contradictory results in the study mentioned above, it is unclear exactly what the physiological mechanisms are at play. Further research is needed.

Possible Side Effects

Magnesium chloride supplements are considered safe if used as directed. Common side effects include stomach upset, nausea, diarrhea, and vomiting. Many of these side effects can be alleviated by taking the supplement with food.

Nearly all forms of magnesium supplements have a laxative effect. Those that are more readily absorbed in the intestines pose a lesser risk since smaller doses are needed.

On the one end of the spectrum, magnesium oxide is more likely to cause diarrhea because it is so poorly absorbed and requires a larger dose. On the other end, magnesium glycinate is the best-absorbed form and poses little risk. Magnesium chloride falls somewhere in between.

Rare side effects include dizziness, fainting, confusion, allergy, and hematochezia (blood in stools). Call your doctor or seek urgent care if any such symptoms develop after taking a magnesium supplement.


Magnesium can bind to certain medication and interfere with their absorption. Possible interactions include:

  • Aminoglycoside antibiotics, like Gentak (gentamicin) and streptomycin
  • Bisphosphonates, like Fosamax (alendronate)
  • Calcium channel blockers, like nifedipine and verapamil
  • Quinoline antibiotics, like Cipro (ciprofloxacin) and Levaquin (levofloxacin)
  • Tetracycline antibiotics, like doxycycline and Minocin (minocycline)
  • Thyroid medications, like Synthroid (levothyroxine)

On the flip side, potassium-sparing diuretics like Aldactone (spironolactone) can increase the concentration of magnesium in the blood and, with it, the risk of side effects.

Separating the doses by two to four hours is often all that is needed to mitigate the interaction. This is especially true with antibiotics that require longer periods of separation.

To avoid interactions, advise your doctor about any and all drugs you are taking, whether they are prescriptions, over-the-counter, nutritional, herbal, or recreational.

Dosage and Preparation

Magnesium chloride supplements are available as tablets, capsules, and powders with doses ranging from 200 milligrams (mg) to 500 mg. They are used to help meet your Recommended Dietary Allowance (RDA) of magnesium as outlined by the Office of Dietary Supplements.

Recommended Dietary Allowance (RDA) of Magnesium
Age Male Female Pregnant Lactating
Birth to 6 months 30 mg 30 mg    
7 to 12 months 75 mg 75 mg    
1 to 3 years 80 mg 80 mg    
4 to 8 years 130 mg 130 mg    
9 to 13 years 240 mg 240 mg    
14 to 18 years 410 mg 360 mg 400 mg 360 mg
19 to 30 years 400 mg 310 mg 350 mg 310 mg
31 to 50 years 400 mg 350 mg 360 mg 320 mg
51 years and over 420 mg 320 mg    

If you are taking a magnesium supplement greater than 350 mg per day, it is recommended that you do so under medical supervision. Magnesium toxicity is rare, but high doses are more likely to cause nausea, vomiting, and dizziness.

Magnesium supplements are meant to bolster your dietary intake, not act as a substitute for a healthy diet.

Among some of the other useful tips:

  • Magnesium supplements can be taken with or without food. If loose stools occur, try taking a lower dose.
  • Extended-release tablets should be swallowed whole. Do not chew, split, or crush the tablet.
  • Magnesium supplements can be stored safely at room temperature.
  • Discard any supplement that is past its expiration date or shows signs of moisture damage or deterioration.

What to Look For

Dietary supplements are not strictly regulated in the United States. Because of this, the quality can vary from one brand to the next.

To ensure quality and safety, opt for supplements that have have been independently tested by a certifying body like the U.S. Pharmacopeia (USP), NSF International, or ConsumerLab. The certification confirms that the supplement contains the ingredients and ingredient amounts listed on the product label.

Always read to the label to check of added ingredients you may be allergic or sensitive to, including gluten and animal-based gelatins.

Bowl of spinach, pumpkin seeds, almonds, magnesium tablets, magnesium capsules, and magnesium powder
Verywell / Anastasia Tretiak

Common Questions

Is magnesium chloride the best supplement choice?

Magnesium salts like magnesium chloride are better able to correct magnesium deficiencies because they can be dissolved in water. Compared to less soluble forms of magnesium, magnesium chloride is absorbed almost completely in the gut, increasing its bioavailability in the bloodstream.

According to a 2017 review in Current Nutrition and Food Science, magnesium chloride (and other magnesium salts like magnesium aspartate, gluconate, citrate, and lactate) have a bioavailability of between 50% and 67%. Organic salts like magnesium chloride are slightly more effective than inorganic salts.

Of all of the available sources, magnesium gluconate has the highest bioavailability overall, while magnesium oxide has the lowest.

What are the best dietary sources of magnesium?

Nuts, seeds, whole grains, dark leafy greens, dried beans, and low-fat dairy products are the richest sources of magnesium. These include:

  • Pumpkin seeds (1 ounce): 168 mg
  • Almonds (1 ounce): 80 mg
  • Spinach (1/2 cup): 78 mg
  • Soy milk (1 cup): 61 mg
  • Edamame (1/2 cup): 50 mg
  • Dark chocolate (1 ounce): 50 mg
  • Peanut butter (2 tablespoons): 49 mg
  • Avocado (1 cup): 44 mg
  • Baked potato (1 medium): 44 mg
  • Brown rice (1/2 cup): 42 mg
  • Plain yogurt (8 ounces): 42 mg
  • Banana (1 large): 32 mg
  • Salmon (3 ounces): 26 mg
  • Low-fat milk (1/2 cup): 24 mg
  • Whole wheat bread (1 slice): 23 mg
  • Chicken breast (3 ounces): 22 mg
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Article Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Rodríguez-Morán M, Guerrero-Romero F. Oral Magnesium Supplementation Improves Insulin Sensitivity and Metabolic Control in Type 2 Diabetic Subjects: A randomized double-blind controlled trial. Diabetes Care.2003 Apr;26(4):1147-52. doi:10.2337/diacare.26.4.1147

  2. Office of Dietary Supplements/National Institutes of Health. Magnesium: Fact Sheet for Health Professionals. Bethesda, Maryland; updated July 11, 2019.

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