If you have sore muscles, slipping into a warm bath with Epsom salt feels amazing. This is almost entirely because you're taking the time to make a nice bath for yourself and pay attention to your body that just did such hard work for you. The whole thing about it relieving soreness? Sorry, but nope.
Photo via Best Running
Think about it - do you really expect the Epsom salts to migrate through your skin and into your muscles? What would they do when they're there, exactly? Our skin's job is to keep substances out, which is why you aren't constantly poisoning yourself with everything you touch.
An article at Pain Science breaks down this theory in excruciating detail, looking at what Epsom salts are supposed to do, whether they penetrate the skin, and what's wrong with popular explanations of the treatment. Bottom line: Epsom salts can give water a silky feel, which you may enjoy on your skin, but that's all.
And that's fine because that makes them great for creating a little bubble of affordable luxury for yourself. Epsom salts are also a handy way to transfer sweet-smelling essential oils into your bath, and are usually way cheaper than fancy bath bombs. (The essential oil is there to smell nice, not to work any herbal magic, of course.) So relax and enjoy your bath salts, now that you know a little more about what they're actually for.
Does Epsom Salt Work? [Pain Science]