Epsom Salt And Skin Absorption: What Science Found Beneath The Surface
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 research recruited 19 healthy adult volunteers (10 men, 9 women, aged 24-64) to test whether bathing in magnesium sulfate (epsom salt) leads to measurable increases in blood and urine levels of magnesium and sulfate.
The design: participants took daily baths (for up to 7 days) in 50-55 °C water (rather hot!) with varying amounts of epsom salt dissolved. Blood samples were taken before the first bath, 2 hours after the first bath, and 2 hours after the seventh consecutive bath; urine was collected before the first bath, 2 hours after each bath, and again 24 hours after the last bath.
What the researchers found? The numbers showed that yes, bathing in magnesium sulfate raised both magnesium and sulfate in the body. Let’s break that down.
What Changed: Magnesium And Sulfate Levels
Magnesium
Magnesium levels in blood plasma are tightly regulated in the body—they normally don’t jump around wildly. In this study, the mean pre-bath magnesium was about 104.68 ppm (± 20.76), and after the first bath rose to roughly 114.08 ppm (± 25.83) in most individuals.
After seven consecutive baths, for those subjects who continued, the mean rose further to about 140.98 ppm (± 17.00).
In urine, magnesium rose more substantially: prior to bathing, the mean was 94.81 ppm (± 44.26), and 2 hours after the first bath, that jumped to 198.93 ppm (± 97.52)—indicating the body filtered out excess magnesium that had crossed into the system.
The researchers interpret this as evidence that magnesium ions did indeed cross the skin barrier and entered systemic circulation (or at least, entered the bloodstream and kidneys) in many cases.
Sulfate
Sulfate (the other half of magnesium sulfate) also showed an increase: free inorganic sulfate in plasma rose from a mean of 3.28 nmol/mg protein ±1.40 pre-bath to 5.59 nmol/mg ±3.08 two hours after the first bath.
Urinary sulfate also increased: pre-bath mean ~623.74 nmols/ml (±352.34), then 2 hours post-bath ~1,093.30 nmols/ml (±388.79). After seven days of bathing, urinary sulfate had returned closer to baseline, suggesting that the body had taken up sulfate into tissue stores (“saturation”) rather than continuously excreting large amounts.
Key Takeaways
- The study identified that a bath water concentration of 1% magnesium sulfate (that’s ~1 g MgSO₄ per 100 ml water; in their UK bath size, ~600 g epsom salt in ~60 litres) produced measurable rises.
- Even baths with ~400 g magnesium sulfate dissolved produced significant rises in many subjects.
- The authors suggest that, for maximal uptake, bathing 2-3 times per week using about 500-600 g of epsom salt per typical bath might be optimal.
- No adverse effects (such as kidney strain) were observed over the 8 days, even at up to 2.5% magnesium sulfate. Urinary protein (a marker of kidney damage) did not significantly change.
A Note On Credibility
While this study is legitimate, it’s important to know that it was not published in a peer-reviewed scientific journal. That means its findings, while interesting and legitimate, have not undergone the rigorous review process that typically confirms scientific reliability.
In simple terms, the study 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 the skin can absorb, how quickly it happens, and whether it leads to meaningful physiological benefits. Still, the Birmingham experiment gives us a valuable starting point: the first structured indication that transdermal absorption of epsom salt may indeed occur.
So, what does that mean for you? Think of it as an encouraging possibility, one that adds a layer of curiosity to your next relaxing soak.
Turning The Science Into Self-Care
Even though the evidence isn’t yet definitive, it’s easy to see why the idea of mineral absorption through bathing is so appealing. A warm bath alone is a proven way to relax muscles, ease tension, and slow down after a busy day.
Adding epsom salt may enhance that experience—especially if magnesium and sulfate do, in fact, cross the skin barrier as this study suggests.
If you’ve been searching for a simple ritual to unwind or soothe sore muscles, try recreating the study conditions safely at home. Fill your tub with comfortably warm water, pour in 500–600 g of epsom salt, and soak for 10–15 minutes.
You can also use any of our bath soaks with essential oils to elevate the experience. For instance, we have a lavender-infused Dry Skin Bath Soak that’s ready to use any time you’re craving calm.
Dim the lights, breathe deeply, and let the water do its quiet work. Whether the benefit comes from the magnesium itself or the act of slowing down, your body and mind both win.
Create a soothing environment: dim the lights, play soft music, place a timer, and simply give yourself permission to pause. Your body may well benefit from the extra magnesium and sulfate crossing your skin—and your mind will likely benefit from the break.
Final Thoughts
The University of Birmingham’s experiment gives hopeful insight into how epsom salt may interact with the body. While it’s not peer-reviewed, its observations still invite curiosity and further research.
The results hint that your skin might be more permeable than we once thought and that a warm epsom salt bath could offer more than just relaxation.
For now, consider each soak a soothing ritual backed by emerging science—a moment where comfort and curiosity meet.
Ready to try it for yourself? Explore our curated selection of epsom salt bath blends and foot soaks at Better Bath Better Body, crafted for indulgence and self-care.
Shop now and turn your soak into a ritual of calm and care.
