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The claim that Epsom salt (Magnesium sulphate) in a bath provides relief from muscle pain is common and is asserted by many sources, including the packages themselves:

  • Wellness Mama

    Body Aches– Add 2 cups to a warm bath and soak for at least 20 minutes to help relieve muscle sprains and for a transdermal magnesium boost.

  • Saltworks

    An Epsom salt bath is known to ease pain and relieve inflammation, making it beneficial in the treatment of sore muscles, bronchial asthma, and migraine headaches. In addition, it has been known to heal cuts and reduce soreness from childbirth. Mix a thick paste of Epsom salt with hot water and apply to get soothing comfort. Try soaking your aching, tired (and smelly) feet in a tub of water with half a cup of our Ultra Epsom Salt.

  • Dr Teals

    Helps relieve muscle tension

  • Westlab

    Helps relax tired aching muscles

  • Epsoak

    A natural remedy for soothing tired and aching muscles.

There are a myriad of other healing benefits attributed to magnesium sulphate, including healing sunburn, removing splinters, promoting weight-loss, and many more, but I am only interested in its purported ability to ease muscle pain.

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    A hot bath is a good way to relax your aching muscles by itself. I'd be dubious about how much bath salts contributes. – c.. Apr 19 '17 at 1:43
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Summary: Other people, including scientists, have searched for a scientific answer to your question, and come up empty. I also come up empty.

This page, by Paul Ingraham, has an extensive write up to answer your question. The page uses fairly good standards of evidence and is up front about the poor quality of the evidence. It is quite well written, but rather long. A lot of my answer is taken from his page, but I have additional pieces of evidence. Note that I have university credentials, and I can therefore read a lot of scientific studies that are behind a paywall for most people. I apologize when you cannot follow my links.

Ingraham was unable to find any published scientific research on soaking in Epsom salts. Before I found his page, I did my own google scholar search and came up empty.


This literature review paper repeated the claims of epsom salt manufacturers and stated that, "little evidenced-based research is available in the medical literature to support these claims." The review paper discusses evidence of healing effects on skin, but nothing on muscles.


This literature review concludes that magnesium cannot penetrate healthy skin.

Transport of Mg2 across skin is a critical precondition for the function of topical, therapeutic compounds in treating skin and inflammatory diseases. . . . Past studies on magnesium and other metal ion permeation through human skin demonstrated that it is not readily absorbed under normal physiological conditions, when the skin is intact and healthy.

In more plain english, If skin keeps the magnesium out, it cannot do anything. Healthy skin keeps the magnesium out. They go on to say that damaged skin may let some magnesium in.

The article later speculates on a way that magnesium may be able to get in through hair follicles. The authors are clear that this is just speculation.


An unpublished study says that soaking in a hot epsom salt bath leads to an increase in magnesium in the blood and urine. Ingraham speculates about how the magnesium got from the bath into the people, but does not draw any conclusions. He also calls the research methods into question.

Ingrahams conclusion matches my own, "There is no good or specific reason to believe that bathing in dissolved Epsom salts will have the slightest effect on muscle soreness or injury recovery time."

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    Saltworks says, in the quote, that it "is known." Isn't that good enough for ya? – PoloHoleSet Apr 19 '17 at 18:17
  • I didn't get the same impression that the second literature review you mentioned concludes magnesium can't penetrate healthy skin - "Absorption of Mg2+ ions across the normal SC could occur under conditions of elevated temperature or changed hydration conditions (for example high salt concentrations)." I'd say their conclusion is more that there's more research to be done. – Rob Watts May 23 '17 at 21:57

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