Epsom Salt Baths: Claims, Magnesium Absorption and Evidence

What Epsom Salt Is and What Is Claimed

Epsom salt is mostly magnesium sulfate. [1] It is sold for adding to a bath, and common claims say that soaking lets magnesium enter the body through the skin and is more effective than swallowed magnesium. [2] Popular claims also include easing sore muscles, calming the nerves and aiding sleep. This page is a claim check. It is information only and gives no recipe, amount or bath temperature. For the ingredient itself, see Epsom salt.

Does Magnesium Absorb Through the Skin?

A 2017 review in the journal Nutrients looked at the evidence on transdermal (through-the-skin) magnesium, including sprays, flakes and magnesium salt baths. Its conclusion was that the propagation of transdermal magnesium is scientifically unsupported. The authors noted that oral magnesium for people who are deficient is well studied, and that marketing of skin products had begun to cast doubt on it. [2]

The review also described a bath study by a researcher at the University of Birmingham, United Kingdom, in which 19 people bathed in Epsom salt daily for a week. Most had a rise in blood magnesium. The reviewers pointed out that this study had been published only on the internet, on a commercial site run by an Epsom salt group, and not in a peer-reviewed scientific journal. [2] So its result is not strong evidence.

Label: no good evidence of benefit for the absorption claim. The question is not settled in every detail, but the best review we read found no reliable support.

Does an Epsom Salt Bath Help Sore Muscles, Pain or Sleep?

Proper evidence not found. We searched PubMed for "Epsom salt", "magnesium sulfate bath randomized" and "transdermal magnesium sulfate bath pain muscle". None returned a trial that compares an Epsom salt bath with a plain warm bath for muscle soreness, pain or sleep. Without that comparison, any relief could come from the warm water itself. Warm water has its own limited evidence for sleep: a 2019 meta-analysis linked a warm bath or shower before bed with better self-rated sleep, and the authors called the research scarce. [3] See warm baths and sleep.

Dead Sea Salt Is Not Epsom Salt

Studies of "magnesium bath salts" are often about a different salt. A study in volunteers with atopic (eczema-prone) dry skin soaked one forearm for 15 minutes in a solution of a commercial Dead Sea salt rich in magnesium chloride, with the other forearm in tap water as the comparison. The salted forearm had better skin barrier function in the subgroup with high starting water loss, better hydration, and less roughness and redness. [4] We could not see how the study was funded. That finding is about skin moisture on a forearm, not about magnesium entering the body, and it used magnesium chloride, not Epsom salt. For eczema, see hydrotherapy for skin conditions.

If You Want Magnesium

Based on the review above, a bath is not a proven way to raise magnesium. Whether you need more magnesium is a question for a clinician. [2] See magnesium and magnesium for sleep for the evidence on swallowed magnesium.