What are Epsom Salts, and are they good for your skin?

December 15, 2019 / Duncan Fisher
They’re magnesium sulfate, and the answer appears to be yes

‘This product contains pure minerals,’ reads the label on a package of Epsom Salts spotted in a supermarket this week. These minerals ‘absorb through the surface of the skin,’ we’re told. They help remove ‘toxins.’ They ‘purify’ something or other. Epsom Salts help you sleep, promises the label. And best of all, they soften your skin.

Without the label, this is a bag of magnesium sulfate, with some perfume. ‘Epsom’ is an English town associated with a spring full of the stuff, in which people bathed in the 17thcentury to cure themselves of things. This particular bag didn’t come from Epsom.

It sounds terrific. But does magnesium sulfate really absorb into you? Does it purify things, and detoxify you? Does it help you sleep? And does it soften your skin?

The answer to most of these is no. This particular label is misleading, to say the least. It talks in pseudo-medical vagueries, and it implies things about Epsom Salts that just aren’t true.

But it says one thing that is true. It’s the part about softening the skin.

Magnesium sulfate does have some legitimate medical uses, too, though the label doesn’t talk about any of those. Epsom Salts actually are a thing.

Let’s explain.

Here’s the deal on Epsom Salts

A ‘salt’ is any crystal solid that you get from an acid reacting with a base. It’s the union of cations and anions. Sodium chloride, table salt, is one. Calcium chloride, which melts ice on your driveway, is another. (Don’t eat that.) Salts are a class of compound, and there are many of them. Magnesium sulfate occurs in nature as mineral ‘epsomite’ and ‘kieserite’. ‘Mineral’ is just the name we give to any inorganic solid that occurs naturally. We manufacture a lot of magnesium sulfate, because we need it in industries like textiles, cement, and fertilizers.

We also use it in medicine.

In its injectable or intravenous form, it’s sometimes used to correct low magnesium levels in the blood, and to control pediatric nephritis and seizures associated with complications in pregnancy. Magnesium sulfate reacts with a great many drugs, and its side effects can be very severe. It’s an actual pharmaceutical molecule, in other words, and it does powerful things. For that reason, you can’t get these preparations, nor should you, without a prescription.* Taken internally, magnesium sulfate is dangerous.

But you can get bags of Epsom Salts** at the supermarket, and you can take a nice bath in them. That’s legal. One reason it’s legal is that magnesium sulfate doesn’t appear to go through your skin in any abundance and do anything to you internally. It’s just not true, whatever package labels may tell you, that Epsom Salts absorb into your body.

The other reason it’s legal is that there’s evidence that your skin likes it. There have been anecdotes for years that seawater bathing helps some people with their eczema. (There is magnesium sulfate in seawater.) It’s probably not without good reason that villagers in old Epsom took dips in their mineral spring. Latterly, there’s also been some research to show that magnesium-rich Dead Sea salt solution improves skin barrier function and hydration, and, in atopic skin, reduces inflammation. Magnesium salts accelerate your skin barrier repair after injury, too. (Notice, by the way, that something that makes your skin barrier stronger is not likely to be something that also absorbs easily through your skin.) The American Academy of Dermatology even recommends an Epsom Salt bath for relief of genital herpes. That’s how much your skin likes Epsom Salts. That’s probably a perfectly good reason to bathe in them.

So, you might well sleep better after a bath in Epsom Salts. But you won’t be ‘purified’ of anything. And you can ignore label talk of ‘toxins.’ And nothing will absorb through your skin. But your skin itself, evidence does suggest, really may be smoother and nicer. On that score, at least, our supermarket label isn’t wrong.

*Can’t you get oral magnesium supplements at the health food store? Yes, but magnesium isn’t the same as magnesium sulfate.

**Why do we say ‘Epsom Salts’ and not ‘Epsom Salt?’ Because magnesium sulfate derives from sodium sulfate and soluble magnesium salt.

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