Surly Amy is currently trapped in the cube-like horror under her cousin’s cabin, fighting off either lamprey ballerinas, pain-worshipping redneck zombies, or unicorns. In the meantime, Mary volunteered to answer her mailbag while she is gone. Don’t fret, she’ll be back shortly!
My husband recently developed an ingrown toenail with a pretty gnarly infection. We went to the doctor, and he prescribed antibiotics and "a remedy your Grandma would love" – Epsom salt soaks. As my husband says, his grandma is a great lady, but she's no scientist.
I'm a nurse, and I know that magnesium sulfate is used intravenously to stop premature labor and treat eclampsia. It can be taken internally as a strong laxative or as a supplement for low magnesium levels. The only information I can find on topical use claims that it draws "toxins" out of the body. As a skeptic, my first instinct is to translate "toxins" to "bullshit" but if you know of any information on the medicinal use of topical magnesium sulfate (Epsom salts), I'd love to hear about it.
Dear Skeptic Nurse,
You’re right to be skeptical whenever you hear the word “toxins.” Doing research on the internet about Epsom Salts is a bit like watching that scene from Idiocracy about electrolytes. (What are Epsom salts? Uh, they’re what muscles/feet crave.) The idea that soaking in a bath with Epsom Salts to draw out toxins seems to be a self-perpetuating myth, because most websites that recommend it as a natural cure usually list no science-based sources. Some of the more “scientific” alternative therapy websites link back to the Epsom Salt Council, whose sole purpose is to promote the usage of Epsom Salts (no conflict of interest there–seems legit to me!).
When people have generic ailments, they soak in Epsom salts and swear the problem is solved. Others who are skeptical because they didn’t notice a difference conclude they must have not added enough Epsom salts to the water. I don’t know the exact logical fallacy that is, so I’m just referring to it as Fucked Up Reasoning.
Since your husband’s doctor prescribed antibiotics, I’m assuming that the soak was suggested to soften the skin around the nail. I am not a medical doctor, but according to my sources (NIH, Mayo Clinic) soaking your feet in warm water is used as a therapy for ingrown toenails to soften up your skin to allow an ingrown toenail to continue growing without getting stuck. The FDA claims that there is no benefit to soaking in salt water vs. regular water and recommends adding some dish soap (with skin softeners) to the foot soak to help with, well, actual skin softening. A Pubmed search yields no published studies on the effects of soaking in warm water with magnesium sulfate. Epsom salts are listed as a drug by the FDA and even though the packaging claims it is beneficial for soaking, the drug facts only indicate its over-the-counter usage as a laxative.
This well-researched article makes a reference to a study (that hasn’t been published yet) that claims soaking in a tub of Epsom salts increases the magnesium levels in blood, which may be beneficial (or may cause Hypermagnesmia). So are Epsom salts mostly harmless in bath water? Not exactly. Soaking in salt water can cause your skin to dry out, and if you already have dry skin this could cause your skin to become more permeable to infections. (This is also why warm water is recommended instead of hot water—same drying effect.)
If you ever have a doctor recommend a magnesium sulfate soak again, ask if there is anything other than anecdotal evidence to prove its efficacy. And always take any advice with a grain of salt.
Got a question you would like some Surly-Skepchick advice on? Send it in! We won’t publish your real name, unless you want us to and creative pseudonyms get bonus points! Just use the contact link on the top left of the page.