Know exactly when and how this magnesium-rich salt can be healing and helpful (versus harmful).

By Elizabeth Yuko
June 03, 2021
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Growing up, our family bathroom always had a full stock of what appeared to be a bright green and blue cardboard milk carton under the sink. At some point, I asked my mom about the mysterious carton, and she explained that it was salt, but a different kind than the salt we used in the kitchen. She and my grandmother added this Epsom salt to their foot baths to help with arthritis.

As an adult, I came to learn about a variety of uses for Epsom salt, both in and out of the bathtub, as well as its wide range of purported health benefits. To learn even more about the various health claims, I asked some experts and studied the research—it turns out that the existing evidence surrounding the alleged benefits of Epsom salt is a mixed bag (or milk carton). Here's what you need to know about the health benefits of Epsom salt, including the best times and methods to use it, and when it's best to skip it.

What is Epsom salt?

Epsom salt, which also goes by the name magnesium sulfate, is a chemical compound made up of magnesium, sulfur, and oxygen. Its less-scientific name actually stems from its prevalence in the village of Epsom in Surrey, England, one of the country's first spa towns, where people came to "take the waters" from a bitter saline spring thought to have medicinal properties. 

The magnesium is key

While Epsom salt has been used for hundreds of years to help treat a variety of ailments, the scientific evidence backing these claims is limited. Many of Epsom salt's healing properties are believed to come from its high magnesium content, a natural mineral that many people don't get in high enough amounts. According to the National Institutes of Health's Office of Dietary Supplements, magnesium plays an important role in many of the body's processes, including regulating muscle and nerve function, blood sugar levels, and blood pressure, as well as making protein, bone, and DNA. 

So we know that Epsom salt contains magnesium, and that magnesium is a mineral in which many people are deficient. What's still not entirely clear is how effective Epsom salt is at providing magnesium to the body. Despite the lack of data from clinical trials, however, many doctors and healthcare professionals continue to recommend different uses for Epsom salt to their patients, implying that there's probably some truth to its anecdotal claims. 

Uses and Health Benefits of Epsom Salts
Credit: Getty Images

5 Common Uses for Epsom Salts

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1 For Post-Workout Recovery

One of the most common uses of Epsom salt is adding it to a warm bath to help soothe muscle pain, soreness or discomfort. As the fitness director and a wellness coach at Hilton Head Health, David Chesworth recommends Epsom salt baths to some of his clients as a way to help their body recover following a workout.

“After exercising, the benefit of Epsom salt comes from magnesium sulfate,” he says. “Magnesium regulates your electrolyte balance, which is needed for calcium regulation and potassium absorption. In an Epsom salt bath, the magnesium ions are released in the water, which may help the body use up glucose and lactic acid, and may provide some relief from soreness, inflammation, and muscle cramps.”

While there’s plenty of anecdotal evidence that an Epsom salt bath can help you feel better after a workout, the research is still fairly sparse. For example, a 2006 study on the relationship between magnesium and physical activity did find that strenuous exercise (the kind that results in additional urinary and sweat losses) may increase a person's magnesium requirements by 10 to 20 percent. However, a 2017 study did not find any evidence that magnesium can be absorbed through the skin—including via a bath. 

That said, taking a warm bath itself can help soothe achy muscles and joints, per the Cleveland Clinic, and adding Epsom salt to your bath isn’t going to cause you any harm. If you find that a post-workout Epsom salt bath speeds up your recovery, there’s no reason to stop (i.e., it’s not going to harm you at all). If you’ve never taken one before and aren’t sure where to start, Chesworth recommends dissolving two-thirds of a cup of Epsom salt in a bathtub filled with warm water, or one-quarter of a cup of it in a foot bath.

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2 For Foot Care and Pain Relief

Bruce Pinker, DPM, a board-certified podiatrist and foot surgeon and the founder and owner of Progressive Foot Care in White Plains, N.Y., recommends Epsom salt soaks nearly every day to his patients. “Epsom salt has been available for consumer usage for decades, and Epsom salt soaks can be very beneficial to sore, injured feet,” he says. 

Again, at this point there’s no research-based evidence that magnesium can be absorbed through the skin, but because of results they’ve seen in their own practice, doctors routinely prescribe it to deal with a wide range of foot-related health issues.

“As a general rule, I recommend two tablespoons [of Epsom salt] be added to a quart of room temperature water—enough water to cover the top of the foot,” Dr. Pinker explains. “Mix the solution and soak the sore and injured foot/feet for 20 minutes.” He advises that people with arthritic feet do these soaks every six to eight hours as needed to provide relief from pain. The Epsom salt foot baths can also help reduce the pain and itching from Athlete's foot, although he says that topical antifungals are usually necessary, as well. 

Finally, Dr. Pinker says that Epsom salt soaks can also assist in resolving the swelling and discomfort from an ingrown toenail. “After an ingrown toenail is corrected by a podiatrist, it is beneficial to soak the affected toe as described above, followed by the application of an antibiotic cream or ointment,” he explains. “The Epsom salt soaking can help facilitate the draining of the ingrown toenail for the more severe cases. Often, I recommend this to my patients.”

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3 For Anxiety

According to Rhonda Mattox, MD, a physician board-certified in psychiatry and neurology, Epsom salt is one of the tools in her toolbox that can be useful for patients with a number of conditions, including anxiety. She explains that she recommends Epsom salt baths to “people who are already on multiple meds, when I don't want the potential fallout of adding another medicine that could contribute to side effects or interactions, or in my patients who don't want any medicines, period.”

Dr. Mattox says people with a magnesium deficiency are more likely to have complaints of anxiety and insomnia. And while acknowledging that “there is no great data to suggest that magnesium is absorbed through the skin,” she recommends Epsom salt baths for patients with mild-to-moderate anxiety—even if the benefits are nothing more than the placebo effect at work. “That does not deter me from recommending it to my patients who do not want medicine, but want relief,” she says. “Why? Because when the placebo effect comes with an improvement of symptoms without a medicine and with very few side effects, I consider it a win.”

4 For Better Sleep Quality

Along with anxiety, Dr. Mattox recommends Epsom salt baths to her patients dealing with insomnia or other sleep-related complaints. Based on self-reporting by patients in her practice (without a control group), she has found that those who take Epsom salt baths report feeling calmer, more relaxed, and find it easier to fall asleep. And again, even if this is because of the placebo effect and not actual magnesium absorption, she still considers it a win.

“As a physician, I want my patients to sleep better and have less pain,” Dr. Mattox says. “If baths can help relax your muscles, reduce your stress and can be a great part of a nightly bedtime ritual that sets you up for a great night's sleep with less pain, then count me in to recommend it with some Epsom salt.”

RELATED: Science Says Bathing Before Bed Could Be the Key to Great Sleep—As Long as You Time It Right 

5 Don't Use It for: Constipation

There’s one use for Epsom salts that you should actively avoid: Dissolving it in water and drinking it. While this method has been touted as an effective laxative for treating constipation, or as a general way to “detox,” ingesting Epsom salt is not a good idea, according to doctors like Robin Rose, DO, a board-certified specialist in gastroenterology and internal medicine, and the founder and CEO of Terrain Health in Ridgefield, Conn.

"I’ve never prescribed this as a remedy,” Dr. Rose says. “Magnesium sulfate is a chemical compound used in colonoscopy preparation. As you know if you've had this procedure, this is an aggressive way to solve your problems.” Additionally, Dr. Rose says that long-term use of Epsom salt ingested as a laxative can cause electrolyte imbalances and fluid shifts, potentially resulting in damage to your kidneys and heart. “The most important thing is to get to the root cause of your constipation and support your gut health in a natural and safe way,” she adds.