People have considered Epsom salt baths a medicament for centuries.
More recently, some have claimed that Epsom salts can also improve recovery, allowing you to bounce back faster after workouts and adapt more effectively to your training.
Is this true, though?
Are Epsom salts actually therapeutic?
And if so, does that mean they’ll also boost your recovery from workouts?
Or, do they belong in the same bucket as other disproven ancient remedies—sleeping next to a human skull, trepanation, burning incense, and so on?
Learn what science says.
The scientific term for Epsom salt is magnesium sulfate heptahydrate (usually shortened to magnesium sulfate), a chemical compound made up of magnesium, sulfur, and oxygen.
It takes its name from Epsom, the town in Surrey, England where it was discovered.
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People commonly use Epsom salt in homemade cosmetic products such as anti-wrinkle cream, exfoliant, and skin ointment, or as plant feed in areas where soil is magnesium-deficient. However, the most common household use of Epsom salt is dissolving it in bathwater.
When you dissolve Epsom salt in water, it releases magnesium and sulfate ions.
Many people believe bathing in water containing Epsom salt allows your skin to absorb the magnesium, which soothes sore muscles, cleanses the body of toxins, reduces pain, induces sleep, relieves constipation, and treats skin conditions.
Rootle around the internet, and you’ll find hundreds of reviews, articles, and videos extolling the benefits of Epsom salt baths.
Most of these benefits are based on the idea that bathing in water containing Epsom salt allows your skin to absorb magnesium more readily than it can from magnesium-rich food, which raises your body’s magnesium level, boosting your health in several meaningful ways.
Advocates of this theory often point to three studies to support this idea.
The first was conducted by the naturopathic doctor and founder of the American Holistic Medical Association, Norman Shealy, who argued that the body absorbs magnesium applied to the skin much faster than magnesium consumed orally.
Shealy’s work was never published in full, making it impossible to verify his claims.
The second was conducted by scientists at the University of Birmingham and showed that bathing for 12 minutes per day for a week was enough to elevate magnesium levels in most people. Like Dr. Shealy’s work, this study was never published in a peer-reviewed journal, and only appears online on the Epsom salt council’s commercial website.
The final study was published in the European Journal for Nutraceutical Research and found that spraying yourself with magnesium oil every day and soaking your feet for 20 minutes twice weekly was enough to increase magnesium levels by ~60%.
This study only involved 9 participants, 1 of whom dropped out before the end, and didn’t report any data on blood levels of magnesium (they measured it another way), making it difficult to corroborate its findings.
In other words, none of these studies are strong enough to give much weight to the idea that you absorb large amounts of Epsom salt through your skin, or that this would be superior to simply eating it.
And this makes sense, given that the top layer of skin—the stratum corneum—consists of 15-to-20 layers of dead cells containing a fibrous, fat-covered protein called keratin that makes our skin highly impermeable. One of the main functions of skin is to prevent foreign substances from entering the body, and it does its job remarkably well.
While it’s possible that a tiny amount of magnesium may still bypass the stratum corneum via hair follicles and sweat glands, these “openings” only account for a small percentage of the skin’s surface (0.1-to-1%, according to some research). Thus, even if magnesium were to pass through the skin, the amount is likely minuscule and not enough to have any impact on your health, performance, or recovery.
Therefore, the basis for most of Epsom salt’s benefits is at best flawed and at worst completely bogus. But does that mean it’s a complete clunker, or are there other benefits worth considering?
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Magnesium plays a role in more than 300 chemical processes in the body, some of which are directly related to anabolism (muscle building) and catabolism (muscle breakdown). Thus, maintaining adequate magnesium levels is crucial if you want to perform at your best and recover optimally.
Unfortunately, no studies have investigated whether Epsom salt baths improve recovery. Since bathing in magnesium-enriched water very likely doesn’t increase your body’s magnesium level, Epsom salt baths are unlikely to enhance muscle recovery.
That said, many people feel subjectively less sore after taking a post-workout Epsom salt bath. This is likely because warm baths probably accelerate recovery, not because Epsom salt has healing properties.
In other words, it’s the pleasant sensation of warm water on your skin that makes you feel good, not the Epsom salts.
Many people believe that Epsom salt baths help detoxify your body by opening your pores and allowing the magnesium to draw toxins out through your sweat glands.
This is just plain wrong.
First, the idea that positively charged molecules (in this case, the dissociated or dissolved magnesium) can pull negatively charged toxins through sweat glands and out of the body has no scientific basis.
Second, toxins aren’t released through sweat glands—sweat is—but sweat is for cooling your body, not excreting impurities (that’s urine’s job).
As such, we can be almost certain that Epsom salt baths do nothing to detoxify your body.
Magnesium alters brain chemistry to promote long and restful sleep by quieting N-methyl-D-aspartate (sleep-inhibiting) receptors and activating γ-Aminobutyric acid (sleep-boosting) receptors. This is perhaps why having low levels of magnesium is associated with disturbed sleep and getting adequate magnesium improves sleep quality and quantity.
This is why many people claim that taking Epsom salt baths helps you sleep better.
As we’ve already seen, you don’t absorb magnesium through your skin, so the magnesium in Epsom salt baths probably isn’t why bathing in Epsom salt can improve your sleep.
What’s more likely is that the warm water is relaxing and somnolent.
That said, you shouldn’t rely on Epsom salt as a long-term treatment as prolonged use may be detrimental to health.
Some people believe bathing in Epsom salt has a similar effect, but there’s no strong evidence to support this.
One study suggests that a Dead Sea salt solution, a cosmetic product containing a similar amount of magnesium as Epsom salt, can improve skin barrier function, treat dry skin, and reduce skin inflammation associated with conditions such as contact dermatitis and psoriasis.
While the authors of this study didn’t include a “conflicts of interest” section in their writeup, the address given at the top of the paper is for the cosmetics company that produces the Dead Sea salt product used in the trial.
In other words, the same people who published the study also manufacture the product being tested, which increases the chances that the results are biased. (The fact they neglected to mention this obvious conflict of interest is also a red flag.)
Regardless, Dead Sea salt is only chemically similar to Epsom salt, not identical, which means we can’t necessarily apply the findings of studies investigating Dead Sea salt to Epsom salt.
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Using Epsom salt in your bathwater rarely produces adverse side effects, though people with sensitive skin may develop a rash. It’s also sensible to avoid Epsom salt baths if you have an open wound.
The idea that Epsom salt baths improve muscle recovery, detoxify your body, reduce pain, induce sleep, treat constipation, or soothe irritated skin is based on the assumption that magnesium permeates your skin.
Well-designed, peer-reviewed studies show this almost certainly isn’t the case, which means every argument in favor of Epsom salt baths doesn’t wash (😉).
As such, the only good reason to take Epsom salt baths is if you enjoy them (or have a fondness for throwing money down the drain—almost literally).
That said, maintaining adequate magnesium levels is essential for various bodily processes, including exercise performance and recovery.
Therefore, keeping your magnesium levels topped off is sensible. A simple way to do this is to eat plenty of magnesium-rich food, such as nuts, seeds, and beans, and supplement with a well-dosed multivitamin, like Triumph for men or women.
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The only proven use of Epsom salt is as a laxative. Therefore, Epsom salt may be a suitable treatment for constipation. Don’t consume Epsom salt orally for a prolonged period, though, as doing so may adversely affect your health.
Be aware that drinking too much Epsom salt can cause nausea, vomiting, and flushed skin, so always follow the manufacturer’s guidelines on dosage.
There’s no reputable evidence that Epsom salt baths improve muscle recovery, detoxify your body, reduce pain, induce sleep, treat constipation, or soothe irritated skin.
Drinking them produces a laxative effect, so they may be a suitable treatment for constipation.
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