An Epsom salt compress is simple to make: dissolve 2 cups of Epsom salt into 2 cups of hot water, soak a clean towel or cloth in the solution, and apply it directly to the affected area. That ratio, listed on FDA-regulated Epsom salt packaging, creates a concentrated solution strong enough to help with bruises, sprains, insect bites, splinters, and general muscle soreness.
What You Need
Gather these before you start:
- Epsom salt: 2 cups (about 500 grams)
- Hot water: 2 cups
- A clean cloth or towel: something absorbent like a washcloth, hand towel, or folded gauze
- A bowl or basin: large enough to submerge the cloth
Use plain, unscented Epsom salt rather than varieties with added fragrances or essential oils, which can irritate skin when held against it for an extended period.
Step-by-Step Instructions
Start by heating your water. You want it hot enough to dissolve the salt fully but not so hot that it burns your skin. Comfortably warm, around the temperature of a hot bath, works well. Water that’s too hot can actually worsen swelling rather than reduce it.
Pour the 2 cups of hot water into your bowl, then stir in the 2 cups of Epsom salt until the crystals dissolve completely. This takes about 30 to 60 seconds of stirring. If you see undissolved granules settling at the bottom, the water may not be warm enough.
Submerge your cloth in the solution and let it soak for a moment. Wring it out just enough so it’s not dripping everywhere but still thoroughly damp. You want the fabric saturated, not merely moist.
Place the wet compress on the sore or swollen area and hold it there for 15 to 20 minutes. You can re-dip the cloth when it starts to cool or dry out. For larger areas like the back or thigh, use a bigger towel and more solution, keeping the same 1:1 ratio of salt to water.
Adjusting the Strength
The 2:2 ratio creates a strong compress. If you find it drying or irritating, you can dilute it. The Mayo Clinic recommends 2 cups of Epsom salt per gallon of warm water for soaking, which is a much milder concentration. For a compress that falls somewhere in between, try 1.5 cups of salt per quart of water. Start with a lower concentration if you have sensitive skin and increase it next time if you want a stronger effect.
What Epsom Salt Compresses Are Used For
The most common uses are soothing bruises and sprains, easing muscle pain from exercise or overexertion, reducing the sting of insect bites, and helping draw out splinters. The compress works partly through the warmth of the water, which increases blood flow to the area, and partly through the concentrated salt solution creating an osmotic pull that may help reduce localized swelling.
A 2024 clinical trial tested magnesium sulfate wet compresses on patients recovering from eyelid surgery. Five days after the procedure, eyelids treated with the salt compress showed significantly less swelling than those treated with standard cold packs (scoring 0.33 versus 1.21 on the swelling scale). The researchers found the compress outperformed traditional cooling for both swelling and bruising.
Does Magnesium Absorb Through Skin?
Epsom salt is magnesium sulfate, and many people assume the magnesium soaks into the body during use. The evidence suggests this happens minimally, if at all. A review published in the journal Nutrients concluded that transdermal magnesium absorption is “scientifically unsupported.” Magnesium ions in solution are too large in their hydrated form to pass easily through skin, and the hair follicles and sweat glands that could theoretically allow some passage make up less than 1% of the skin’s surface. Studies measuring blood magnesium levels after two hours of bathing in magnesium solutions found no change in magnesium, calcium, or phosphate levels.
This doesn’t mean the compress is useless. The concentrated salt solution still draws fluid through osmosis, and the warm, moist application increases circulation to the area. The benefits are real, just more local than systemic.
How Often to Use One
You can apply an Epsom salt compress two to three times per day for general soreness or swelling. Each session should last about 15 to 20 minutes. Re-wet the cloth as needed to keep it warm and saturated throughout the session. For acute injuries like a fresh sprain, wait 48 hours before using a warm compress of any kind, since heat can increase swelling in the first couple of days.
Safety Considerations
Avoid applying an Epsom salt compress to broken skin, open wounds, or areas with active infection. The salt can sting and potentially worsen irritation in damaged tissue. If you notice skin redness, a rash, or increased irritation after use, stop and rinse the area with plain water.
People who are pregnant or have diabetes should avoid topical Epsom salt use unless cleared by a doctor. Diabetes in particular affects skin integrity and circulation in ways that make salt solutions riskier.
After removing the compress, rinse the treated skin with clean water and pat dry. The salt can leave a residue that draws moisture out of your skin over time, so applying a gentle moisturizer afterward helps prevent dryness, especially if you’re using compresses multiple times a day.