Soaking in an Epsom salt bath has been a popular home remedy for relieving muscle soreness for generations. Many individuals use this method after strenuous activity, raising questions about its actual effectiveness. This article explores the science behind Epsom salt baths and their impact on sore muscles.
Understanding Epsom Salt
Epsom salt, despite its common name, is chemically distinct from table salt. It is a naturally occurring mineral compound known as magnesium sulfate (MgSO4), consisting of magnesium, sulfur, and oxygen.
Its name originates from Epsom, Surrey, England, where it was discovered bubbling from an underground spring in the early 17th century. A farmer, Henry Wicker, reportedly found water in 1618 that healed scratches and rashes. Epsom salt typically appears as white, crystalline solids that readily dissolve in water.
The Theory of Magnesium Absorption
The theory behind Epsom salt baths for sore muscles is transdermal absorption, suggesting magnesium from dissolved salt can be absorbed through the skin. Magnesium is an essential mineral involved in over 300 enzymatic reactions within the human body.
Magnesium plays an important role in muscle and nerve function. It helps regulate muscle contractions and relaxation by acting as a natural calcium blocker, preventing excessive muscle contraction that can lead to cramps and spasms. Magnesium is also involved in transmitting electrical signals between the brain, spinal cord, and muscles, helping to stabilize nerve cells and ensure proper communication. Proponents suggest that increasing the body’s magnesium levels through baths could directly benefit muscle recovery and reduce soreness.
What Research Shows
Despite widespread belief, robust scientific evidence for significant transdermal magnesium absorption from Epsom salt baths, or their direct efficacy for muscle soreness, is limited. While some studies suggest magnesium ions are small enough to potentially pass through the skin, the amount absorbed from a bath to achieve systemic effects is generally considered minimal. Research indicates that while sulfates may rapidly penetrate the skin, magnesium absorption through the skin from bathwater is less clear.
Studies have investigated transdermal magnesium absorption from creams or sprays, with some showing increases in intracellular magnesium or trends toward increased serum magnesium, particularly in non-athletic individuals. However, these findings do not directly translate to Epsom salt baths, where the concentration and duration of exposure differ. Regarding muscle soreness, studies have shown that while warm water immersion can reduce perceived pain and disability, the addition of Epsom salt to the water did not provide additional benefits compared to warm water alone. Any relief experienced might be attributed more to the relaxing effects of a warm bath rather than significant magnesium absorption through the skin.
Using Epsom Salt Safely
For those using Epsom salt baths, proper preparation and safety precautions are important. Add about 2 cups (approximately 475 grams) of Epsom salt to a standard-sized bathtub filled with warm water. The salt should be added while the water is running to help it dissolve completely.
Soaking for 15 to 30 minutes is generally recommended, allowing time for relaxation without over-drying the skin. Water temperature should be comfortably warm, not excessively hot. Avoid ingesting Epsom salt, as it can act as a laxative and, in large amounts, lead to severe side effects like diarrhea, bloating, upset stomach, or even magnesium overdose, which can affect heart function. Individuals with kidney disease, heart conditions, severe skin inflammation, open wounds, or those who are pregnant, should consult a doctor before use. Epsom salt baths should not be considered a substitute for medical treatment.