How Do Epsom Salts Reduce Swelling?

Epsom salt is bath salt derived from distilled, mineral-rich water. This magnesium sulfate compound, named after the town of Epsom, England, is widely used in therapeutic soaks and baths. Among its many claimed benefits, soaking in Epsom salt is touted as a way to decrease tissue swelling. However, there's little, if any proof these soaks actually work. Since swelling is caused by a variety of factors, all with different management strategies, it's best to seek guidance from your doctor on how to manage your swelling before using home treatments.

The magnesium content of Epsom salt is believed to be the source of its claimed benefits. This mineral plays an important role in muscle and nerve function, and is known to decrease inflammation -- which is associated with tissue swelling. So soaking your body in an Epsom salt bath is thought to increase body levels of magnesium, which in turn decrease inflammation -- and swelling. But this mechanism of action is only valid if enough magnesium can be absorbed through the skin to provide a therapeutic benefit, something that has yet to be proven by quality, published research.

Most of the health claims behind the use of Epsom salt baths have surprisingly little research to back them up. In fact, one research review concluded there is no published data to show that beneficial amounts of magnesium can absorbed through the skin, although another journal article proposes that absorption of magnesium might be enhanced by exposing the skin to salty, heated water. On the other hand, soaking in hot water, even without bath salts, has been shown to help with pain management and improve blood flow to the skin. So these soaks may be a soothing way to manage stress and relieve general muscle aches and pains.

Swelling is managed by understanding and treating the cause. So if your swelling is new onset or severe, it's best to speak with your doctor to understand the cause before attempting home treatment. While soaking in Epsom salt may not be inherently harmful, these soaks may not help manage swelling from most causes. For instance, if your swelling is related to a injury, treatment involves rest, elevating the affected limb, nonsteroidal anti-inflammatory medications such as ibuprofen or acetaminophen, and cold therapy -- or icing the area to reduce swelling.

Overall or generalized swelling may be related to heart, lung or kidney disorders, and this swelling can be aggravated by standing for long periods of time or by consuming too much sodium. Swelling of a specific limb or body area may be related to injury, blood clot, infection, allergy or blockage of a lymph vessel -- called lymphedema. If your swelling is new, and not clearly related to an injury that can be treated at home, see your doctor. Seek immediate medical attention if your swelling appears suddenly, if you have swelling of only one leg, or if your swelling is accompanied by significant pain, tenderness, shortness of breath or coughing up blood.

Reviewed by Kay Peck, MPH RD