Epsom salt is a naturally-occurring mineral salt that’s often used to soothe muscle soreness and reduce stress. This compound breaks down into magnesium and sulfate ions when dissolved in water, but it doesn’t dissolve in alcohol-based liquids.

While there is no concrete evidence to explain Epsom salt’s health benefits, people have anecdotally sworn by its anti-inflammatory and pain-relieving effects for centuries, according to Jana Abelovska, MPharm, a pharmacist at the U.K.-based Click Pharmacy.

Some also claim that magnesium can help increase serotonin production, Abelovska said, leading to a reduction in feelings of anxiety and depression.

Laura Purdy, MD, a board-certified family medicine physician, said people also use Epsom salt for a wide range of ailments, including arthritis, ingrown toenails, sunburns, and minor injuries like bruises, scratches, and sprains.