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Epsom salt is having a resurgence, leaping out of Grandma's book of home remedies into "float and soak" treatments at posh spas. Here's what you need to know about this traditional-yet-trendy wellness product.

What Is Epsom Salt?

Bearing no similarity to regular table salt other than in appearance, Epsom salt is actually another name for the chemical compound magnesium sulfate. It was discovered in the 17th century in a spring in the English town of yep, you guessed it Epsom.

What's Epsom Salt Used For?

While Epsom salt has been FDA-approved only as a treatment for constipation (when taken orally), it's also used externally by folks looking to reduce muscle soreness and inflammation, relieve stress and soothe irritated skin. Still others claim it cures insomnia and athlete's foot, among other ailments. So how did Epsom salt get its reputation as a cure-all?

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In a word, magnesium. That is, a hugely important mineral for many biological processes. Magnesium boosts your body's immune system, regulates blood pressure, strengthens bones, keeps blood sugar in check and even increases our tolerance for pain. Recent studies have also shown promise in other uses: A December 2014 study in the Norway-based publication Acta Paediatrica found that taking magnesium sulfate through an IV could help treat asthma, and the journal Stroke published a review in April 2019 that found the same administration could aid stroke sufferers in their recovery.

It's easy to see how the concept of Epsom salt baths caught on, then. How could submerging your entire body in magnesium-infused water possibly be bad? It isn't but here's the thing: Magnesium can easily be used by the body when magnesium-rich foods are eaten (pumpkin seeds, almonds and spinach top the list) or magnesium supplements are taken. But researchers have doubts that magnesium can be absorbed, at least efficiently, through the skin. A review of the research on magnesium absorption in the journal Nutrients, released in August 2017, found inconclusive evidence that the benefits of magnesium can be obtained by absorbing it, either through baths or creams.

Warning

When ingested, higher-than-therapeutic doses of magnesium sulfate can be toxic, so never take more than what your doctor has directed.

De-stress with Epsom Salts

Still, that doesn't mean that a nice long soak in an Epsom bath is a waste of time. The warm water and "time-out" factor of tub time can help reduce stress levels. Warm water in itself soothes sore muscles. And the addition of Epsom salts makes the water feel "softer," like it's gliding over your skin.

You can try it at home by adding two cups of Epsom salt to a warm bath. Or treat yourself to a session in a float tank. The water in those specialized treatment facilities is heavily imbued with Epsom salt, which make it more buoyant and thus easier to float on.

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Possible Beauty Benefits

Epsom salt can be used in a variety of ways on the skin. Try mixing Epsom salt with a low-scent oil, such as corn or canola, to make an easy, economical exfoliator to slough off dead skin cells and soften callouses.

Soaking feet in Epsom salt-infused water softens them for an at-home pedicure and makes it easier to remove splinters from the skin. The treated water may also reduce the swelling and itch of bug bites.

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Anecdotal evidence suggests that Epsom salt both absorbs excess oil from hair and exfoliates a dry, itchy scalp. Try combining equal parts Epsom salt and conditioner and applying it to your hair and scalp. Wrap your head in a towel and relax for 20 minutes, then rinse with warm water. (In a hurry? You can also mix a generous pinch of Epsom salt with your shampoo and wash hair in the shower as usual.) Removing dead skin cells and stimulating the scalp has the potential to help increase blood circulation in the scalp and make hair look more voluminous.

What to Look for When Buying Epsom Salt

Epsom salt is sold in many supermarkets and drugstores. Be sure to look for the “USP” label, which ensures the product has been manufactured, tested and certified to meet both FDA and United States Pharmacopeia standards.

If you want to try drinking an Epsom salt solution for constipation, check in with your doctor first. If you get the green light, be sure the one you buy is unscented, and carefully follow your doctor's dosage instructions.

If you're picking up Epsom salt for a bath or foot soak, you might look for products that have been combined with essential oils, such as Dr. Teal's Soothe & Sleep Epsom Salt scented with lavender.

Watch for Potential Side Effects

Side effects of ingesting Epsom salt may include abdominal cramping, upset stomach and diarrhea in some people. In higher-than-therapeutic doses it can be toxic, so never take more than what your doctor has directed. If you notice hives, swelling or have difficulty breathing, you may be allergic to Epsom salt and should get medical help right away.