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Epsom salt: soaks, foot baths and what the science says
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- Plain Epsom salt (magnesium sulfate USP). Best for: Warm soaks for minor sprains and bruises. See options on Amazon
- Unscented Epsom salt foot soak. Best for: Sensitive skin and foot soaks. See options on Amazon
- Large bag Epsom salt. Best for: Regular baths. See options on Amazon
What Epsom salt is
Epsom salt is magnesium sulfate. A Walgreens Epsom salt label on DailyMed lists magnesium sulfate USP 100% with no inactive ingredients, labeled as a soaking aid for minor sprains and bruises and as a saline laxative. Each teaspoon contains magnesium 495 mg.
| Label use | How it is used | Key caution |
|---|---|---|
| Soaking aid | Dissolved in a bath or foot soak for minor sprains and bruises | Follow package directions |
| Saline laxative | Dissolved in a full glass of water and swallowed | Ask a doctor first with kidney disease or a magnesium-restricted diet |
Does magnesium soak in through the skin?
Epsom baths are often marketed as a way to absorb magnesium. A 2017 review in Nutrients, Myth or Reality: Transdermal Magnesium?, evaluated the evidence on magnesium sprays, flakes and salt baths and concluded that the promotion of transdermal magnesium is scientifically unsupported. The authors noted that the benefits of oral magnesium in deficiency are well documented, but that the marketing claims for skin absorption are not.
So enjoy a warm soak for comfort, but do not rely on it to raise your magnesium levels. If you think you are low in magnesium, ask your doctor about testing.
Magnesium chloride bath flakes are a different compound sold with similar claims; see our magnesium bath flakes guide for how the two compare.
Epsom salt foot soaks
Warm foot soaks show up in several care routines. The American Academy of Dermatology (AAD) suggests soaking a corn or callus in warm water for about five to 10 minutes, until the skin softens, before gently filing. Mayo Clinic suggests soaking an ingrown toenail in warm, soapy water for 10 to 20 minutes, 3 to 4 times a day.
- Use warm, not hot, water and test it with your hand first.
- Dry well afterward, including between the toes.
- Moisturize the tops and bottoms of your feet after soaking, but not between the toes.
For calluses, see our pumice stone guide and urea foot cream guide.
Who should not soak
NIDDK advises people with diabetes not to soak their feet because the skin gets too dry, and to check their feet every day. The same caution makes sense for numbness or poor circulation, where you may not feel water that is too hot.
- Skip soaks over open wounds or infected skin.
- Stop if your skin becomes irritated.
- See a provider for a sprain that does not improve, or for a red, warm, painful toe.
For people who should not soak, see our cracked heels guide for a no-soak routine with moisturizer.
Taking Epsom salt by mouth
The laxative use is a medicine use with real limits. The label says to ask a doctor before use if you have kidney disease, a magnesium-restricted diet, stomach pain, nausea or vomiting, or a sudden change in bowel habits lasting more than 2 weeks, and to ask a doctor or pharmacist if you take a prescription drug. It says not to use more than directed, not to exceed 2 doses per day, and that it is not recommended for children under 6.
Stop and ask a doctor if you have rectal bleeding, no bowel movement after use, or need a laxative for more than 1 week. If pregnant or breast-feeding, ask a health professional first. Keep it out of reach of children.
Choosing Epsom salt
- Look for USP. The DailyMed labels list magnesium sulfate USP; plain Epsom salt has no added ingredients.
- Plain or scented. Scented blends add fragrance and oils; plain Epsom salt has nothing added, which keeps things simple if your skin is sensitive.
- Read the label use. Only products labeled as a laxative should ever be taken by mouth, and only as directed.
- Store sealed. The label says not to use it if the heat-sealed pouch is improperly sealed.
What to look for when you buy
Plain Epsom salt (magnesium sulfate USP)
Best for: Warm soaks for minor sprains and bruises
DailyMed labels list magnesium sulfate USP 100% as a soaking aid for minor sprains and bruises.
Watch out: Skip foot soaks if you have diabetes; follow package directions.
See options on AmazonUnscented Epsom salt foot soak
Best for: Sensitive skin and foot soaks
Plain, unscented Epsom salt has no added fragrance or oils.
Watch out: Dry between the toes after soaking.
See options on AmazonLarge bag Epsom salt
Best for: Regular baths
Epsom salt is widely sold in multi-pound resealable bags.
Watch out: Keep it sealed and out of reach of children.
See options on AmazonQuestions people ask
- What is Epsom salt good for?
- Labels list it as a soaking aid for minor sprains and bruises and as a saline laxative.
- Does magnesium absorb through the skin in an Epsom bath?
- A 2017 review concluded transdermal magnesium claims are scientifically unsupported.
- How long should I soak my feet?
- AAD suggests about five to 10 minutes for corns and calluses; Mayo Clinic suggests 10 to 20 minutes for an ingrown toenail.
- Can people with diabetes use Epsom salt foot soaks?
- NIDDK advises people with diabetes not to soak their feet.
- Is it safe to drink Epsom salt?
- Only a laxative-labeled product, only as directed, and ask a doctor first with kidney disease.
Sources
- Walgreens Epsom Salt (magnesium sulfate) label (dailymed.nlm.nih.gov), DailyMed, National Library of Medicine
- Myth or Reality: Transdermal Magnesium? (pmc.ncbi.nlm.nih.gov), Nutrients (PMC5579607)
- How to treat corns and calluses (aad.org), American Academy of Dermatology
- Ingrown toenails: Diagnosis and treatment (mayoclinic.org), Mayo Clinic
- Diabetes & Foot Problems (niddk.nih.gov), National Institute of Diabetes and Digestive and Kidney Diseases