Imagine sinking into a warm bath and wondering: can the minerals in epsom salt actually cross your skin barrier and enter your body? That’s exactly what the Report on Absorption of Magnesium Sulfate (Epsom Salts) Across the Skin set out to explore.
Conducted at the University of Birmingham, the study involved 19 healthy volunteers (10 men and 9 women, ages 24–64) who bathed daily in magnesium sulfate solutions for up to seven days. Researchers wanted to know if bathing could raise magnesium and sulfate levels in the blood and urine.
Participants soaked in 50–55 °C water containing varying amounts of epsom salt. Blood samples were collected before the first bath, two hours after the first bath, and again after the seventh consecutive bath. Urine samples were taken before and after each session to track mineral changes.
What Changed: Magnesium And Sulfate Levels
Magnesium levels in the blood are normally steady, but in this experiment, they increased. Before bathing, the average magnesium level was 104.68 ppm; after the first bath, it rose to about 114.08 ppm, and after seven baths, it reached roughly 140.98 ppm.
Urinary magnesium also jumped—from an average of 94.81 ppm before bathing to 198.93 ppm two hours later—suggesting the body absorbed magnesium and filtered out the excess through urine. The researchers interpreted this as evidence that magnesium ions may have crossed the skin barrier.
Sulfate levels rose, too. Plasma sulfate increased from 3.28 nmol/mg protein before the bath to 5.59 nmol/mg after the first session. Urinary sulfate rose from about 624 nmols/ml to over 1,000 nmols/ml.
After seven days, urinary levels dropped closer to normal, suggesting the body may have stored sulfate in tissues rather than excreting it continuously.
Key Takeaways
The study found that dissolving about 600 g of epsom salt in an average-size bathtub produced measurable increases in both magnesium and sulfate levels. Even smaller amounts—around 400 g—caused noticeable changes in many participants.
The researchers suggested that bathing two to three times a week with 500–600 g of epsom salt might be ideal for maximum absorption. No side effects were reported, even with stronger solutions (up to 2.5%).
A Note On Credibility
While this study is legitimate, it wasn’t published in a peer-reviewed scientific journal. That means its findings haven’t been formally verified through the scientific review process.
In short, it provides early evidence—not final proof—that magnesium and sulfate can be absorbed through the skin. More research is needed to confirm how much magnesium is absorbed, how fast it happens, and whether it provides real health benefits.
Turning The Science Into Self-Care
Even if the evidence isn’t conclusive, soaking in epsom salt remains a simple way to relax and unwind. Try replicating the study’s setup: fill your tub with comfortably warm water, dissolve about 500–600 g of epsom salt, and soak for 10–15 minutes.
Dim the lights, breathe deeply, and let the warmth calm your body and mind. Whether the benefits come from the minerals themselves or the soothing ritual, your soak can be both restorative and relaxing.
Curious to experience it yourself? Explore our epsom salt bath blends and foot soaks at Better Bath Better Body, crafted to turn your bath into a ritual of calm and care.
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