Epsom Salts Are Trendy, But Do They Actually Work?

From your grandma’s folk remedies to the “float therapy” tanks you might have noticed at spas, people swear by Epsom salt. But a bath full of the crystals might not be all it’s cracked up to be.

The theory is, dissolving Epsom salts—or magnesium sulfate heptahydrate, as scientists say—in your bathwater helps your body absorb much-needed magnesium. The mineral helps your body boost its immune system, keep blood pressure in check, strengthen bones, regulate blood sugar, and more.

Magnesium has been shown to block NDMA receptors, which tell your brain when you’re hurt, says Amy Baxter, MD, founder and CEO of Pain Care Labs in Atlanta. “If you block those receptors, they don’t get the message that you’re hurt,” she says. “Magnesium blocks the receptors, so you perceive pain less.” Plus, research shows magnesium could fight inflammation, and studies have even found that taking magnesium sulfate through an IV could help soothe migraines, treat asthma, and even boost stroke recovery. So it seems to make sense that soaking in a big bath of magnesium could treat a host of health problems.

But delivering magnesium directly into the blood is different from sitting in a bath and hoping the minerals absorb. No peer-reviewed studies have shown Epsom salt baths actually boost magnesium levels in the body. On the other hand, one small Israeli study actually found that even applying a lotion containing magnesium sulfate straight on the skin didn’t raise magnesium levels. “The skin, though permeable and can absorb things, really does not absorb things very quickly—especially Epsom salts,” says Alex Foxman, MD, FACP, of the Beverly Hills Institute and founder of mobile doctor app Prive MD.

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That said, not many studies have looked at Epsom salts specifically. “Absence of proof is not proof of absence,” says Dr. Baxter, who is optimistic that future studies might find more benefits. Some studies have shown mud baths are more effective when applied directly on the skin than with a piece of nylon blocking it. Mud baths contain minerals, so the body might be absorbing magnesium through those, says Dr. Baxter. More research might show similar benefits from Epsom salt baths, but it’s too early to tell.

Even without definitive evidence, some people, like Mao Shing Ni, PhD, a doctor of acupuncture and Chinese medicine in Los Angeles, and author of Secrets of Longevity: Hundreds of Ways to Live to Be 100 do recommend Epsom salts to patients because they’ve heard positive feedback anecdotally. “It’s perfectly safe,” he says. “You don’t want to take them every day for the rest of your life, but you can take them temporarily to relieve pain and cramps.”

Still, patients who swear by Epsom salts might think it’s the magnesium sulfate, when simple warm water is really behind their pain relief, says Dr. Foxman. “The benefits that come from heat from water—which is an opportunity to relax—and the benefits of heat on capillary dilation at skin level, for some relieves pain,” he says.

Plus, adding a scoop of Epsom salts might make your soak extra relaxing. “The water feels better,” says Dr. Foxman. “It does have more of a silky feeling. That feeling could help patients as well.” Just don’t expect miracles. Instead, he suggests soothing sore muscles by stretching, keeping hydrated, and using OTC pain medications when necessary. Learn more ways to relieve muscle pain.

And before you totally write off Epsom salts, consider using them in a new way. The gritty salts make a great exfoliant for your skin, and could be used to give your hair more volume, says integrative health expert Taz Bhatia, MD, founder of CentreSpring MD in Atlanta. “Magnesium sulfate soaks up the excess oil from hair that causes it to look flat and lifeless,” she says. “To avoid over-drying, wash your hair with Epsom salt and shampoo every other time.” Check out these other natural beauty treatments, too.