Magnesium sprays, flakes and Epsom baths, do they work?
What magnesium oil and Epsom salt are, what small studies of sprays, creams and baths found, and how a spray compares with magnesium by mouth.
- Written by
- Ben L.
- Last updated
- Reading time
- 8 min read
Overview
Studies haven't shown that magnesium sprays, creams or Epsom salt baths raise magnesium in healthy people, because the skin's outer layer is a barrier to it. Small studies in people with low magnesium found rises in some. Warm baths before bed help people fall asleep, and food or supplements by mouth are the tested way to get magnesium.
Key points
- Magnesium oil is magnesium chloride dissolved in water, and Epsom salt is magnesium sulphate.
- A 2017 review called the idea that magnesium gets through the skin scientifically unsupported.
- In a placebo-controlled trial of 25 adults, a magnesium cream didn't clearly raise blood magnesium.
- Warm baths 1 to 2 hours before bed helped people fall asleep faster in a review of 17 studies.
- Bath salts aren't for swallowing, and an accidental Epsom salt overdose by mouth was fatal in one case report.
A bottle labelled "magnesium oil" isn't an oil. It's magnesium chloride dissolved in water, a brine you spray on and rub into your skin [1]. The real question is whether the magnesium gets through.
So far, studies haven't shown that a magnesium spray, cream or bath raises magnesium levels in healthy people, and a 2017 review called the idea scientifically unsupported [2]. Small studies in people with low magnesium found rises in some of them [1][3]. Warm baths and showers before bed have their own evidence for sleep [4]. This guide explains each product, what the studies found and how a spray compares with tablets.
What is magnesium oil?
Magnesium oil is a strong solution of magnesium chloride in water. It's sold as sprays, and the same idea is behind magnesium gels and creams. Bath products such as magnesium flakes and Epsom salt go in the water instead [2].
Epsom salt is a different compound, magnesium sulphate [2]. So a magnesium bath can mean either salt, depending on the pack.
Check the label for the milligrams of magnesium in each spray or scoop. Many creams and oils don't state it, which makes it hard to know how much you're putting on [5].
Does magnesium spray work?
Studies haven't shown that it raises magnesium in healthy people. To reach your blood, magnesium has to cross the outer layer of your skin. That layer lets fat-loving substances through, while magnesium in a spray is a charged particle that struggles to pass [2].
Some may get in through hair follicles and sweat glands. These cover only about 0.1 to 1% of the skin's surface, though [2].
A small trial at the University of Hertfordshire tested a cream in people. In it, 25 adults used a magnesium cream with 56 mg a day or a placebo cream for 2 weeks. Blood magnesium in the magnesium group rose from 0.82 to 0.89 mmol/L, but the rise wasn't statistically clear. It was clear only in the people who weren't athletes, and no one had a skin reaction [5]. One of the authors has a financial interest in magnesium creams.
What are the benefits of magnesium spray?
Sprays, gels and creams have been tested for muscle recovery, cramps and fibromyalgia, and for raising low magnesium. The studies are few and small, and the table sums them up.
| Use | What studies found | Evidence |
|---|---|---|
| Blood magnesium in healthy adults | A small rise that wasn't statistically clear, in 25 adults over 2 weeks [5] | Early |
| Muscle recovery | No difference from a placebo gel in soreness, strength or blood markers, in 35 active adults [6] | Early |
| Low magnesium with an ileostomy | Blood magnesium rose in 2 of 6 people over 6 weeks, and 5 said their cramps eased [1] | Early |
| Low magnesium after a kidney transplant | Blood magnesium rose over 2 months in 21 people but stayed below normal [3] | Early |
| Fibromyalgia | Better questionnaire scores after 4 weeks in the 24 women who finished [7] | Early |
Two of these were placebo-controlled. One found a small, unclear rise in blood magnesium and the other found no effect on recovery after downhill running [5][6].
The other three had no comparison group, so some of the gains could come from time or expectation. The ileostomy study ran at St Mark's Hospital in Harrow, and the spray's maker supplied it and paid for the lab tests [1].
Do Epsom salt baths work?
For raising magnesium, the evidence is thin. One study behind the claim had 19 people soak in Epsom salt baths for 12 minutes a day for 7 days. It was published on the Epsom Salt Council's website, not in a peer-reviewed journal, and a review judged it of questionable quality [2].
For sleep, the warm water has better evidence. A review of 17 studies found that a bath or shower at 40 to 42.5°C, taken 1 to 2 hours before bed, helped people fall asleep faster and rate their sleep better. As little as 10 minutes was enough [4].
So run the bath for the warmth, and look to food or tablets for the magnesium.
Magnesium spray or tablets?
Most of the trials on our page of magnesium studies give magnesium by mouth.
The NHS advises 300 mg of magnesium a day for men and 270 mg for women aged 19 to 64, and says 400 mg or less a day from supplements is unlikely to cause any harm [8]. It adds that you should be able to get all the magnesium you need from a varied and balanced diet [8]. Our guide to how much magnesium you need a day adds it up.
Here's a worked example for a spray. In the hospital study, 20 sprays a day gave 150 mg of magnesium, which works out at 7.5 mg a spray [1]. To match the 270 mg figure, you'd need 36 sprays a day, and that's if every milligram got through your skin. That's a lot of spraying.
In practice, if your aim is more magnesium, food and supplements by mouth are where the evidence sits.
Does magnesium spray have side effects?
The studies above reported no side effects from the spray or cream [1][5]. The team behind a newer magnesium gel says classic magnesium oils can leave a sticky film and cause itching, because of their high salt content [3]. If a spray stings or itches, rinse it off.
Don't swallow bath salts. In one case report, a woman with normal kidneys died after an accidental overdose of Epsom salt taken by mouth [9]. Keep the bag away from children.
Taken by mouth in high amounts, magnesium can cause diarrhoea [8]. Our guide to magnesium side effects covers that in more detail.
Where Nooroots fits
Nooroots Triple Magnesium is a food supplement with magnesium glycinate, citrate and malate, in three capsules a day. Magnesium contributes to normal psychological function and to a reduction of tiredness and fatigue [10].
Frequently asked questions
How much magnesium spray should I use a day?
Follow the label, because strengths vary. In one hospital study, 20 sprays a day gave 150 mg of magnesium [1].
Where should you spray magnesium oil?
Studies sprayed it on the chest, back, arms and legs, then rubbed it in [1][7]. Avoid broken or irritated skin.
Can you absorb magnesium through your skin?
A little may get in through hair follicles and sweat glands, but a review found no good evidence that it raises levels in healthy people [2].
Does magnesium spray help you sleep?
We found no trial of magnesium spray for sleep. Warm baths and showers 1 to 2 hours before bed helped people fall asleep faster in a review of 17 studies [4].
Why does magnesium oil itch or tingle?
The makers of a newer magnesium gel put it down to the high salt content of classic magnesium oils [3]. If it bothers you, rinse it off.
How long should you soak in an Epsom salt bath?
For sleep, warm baths helped from as little as 10 minutes, taken 1 to 2 hours before bed [4]. Those studies tested warm water, not Epsom salt.
Read more about the daily amount in our guide on how much magnesium you need a day.
References
Every source here is listed so you can read it yourself. This guide is for general information and doesn't replace advice from your GP. We check it again at least every six months.
- Nightingale J, Bakir IA, Adaba F (2024). Pilot study of a topical magnesium preparation to treat hypomagnesaemia in patients with an ileostomy. Intestinal Failure 2: 100018. PMID 41648083
- Gröber U, Werner T, Vormann J, Kisters K (2017). Myth or Reality: Transdermal Magnesium? Nutrients 9(8): 813. PMID 28788060
- Moisa C, Bănică F, Rațiu IA, Gligor O, Vicaș LG, Rațiu CA et al. (2026). Topical Magnesium Orotate Lipogel in Kidney Transplant Recipients with Persistent Hypomagnesemia. Nutrients 18(16): 2740. PMID 42654320
- Haghayegh S, Khoshnevis S, Smolensky MH, Diller KR, Castriotta RJ (2019). Before-bedtime passive body heating by warm shower or bath to improve sleep: A systematic review and meta-analysis. Sleep Medicine Reviews 46: 124-135. PMID 31102877
- Kass L, Rosanoff A, Tanner A, Sullivan K, McAuley W, Plesset M (2017). Effect of transdermal magnesium cream on serum and urinary magnesium levels in humans: A pilot study. PLOS ONE 12(4): e0174817. PMID 28403154
- Coates AM, Patel DV, Binet ER, Gibala MJ (2025). No Effect of Topical Application of a Commercial Magnesium Gel on Exercise Recovery in Active Individuals. International Journal of Sport Nutrition and Exercise Metabolism 35(5): 416-423. PMID 40537122
- Engen DJ, McAllister SJ, Whipple MO, Cha SS, Dion LJ, Vincent A et al. (2015). Effects of transdermal magnesium chloride on quality of life for patients with fibromyalgia: a feasibility study. Journal of Integrative Medicine 13(5): 306-313. PMID 26343101
- NHS. Vitamins and minerals: others (magnesium section). Page last reviewed 3 August 2020. Accessed 30 October 2026. nhs.uk/conditions/vitamins-and-minerals/others
- Shoaib Khan M, Zahid S, Ishaq M (2018). Fatal Hypermagnesemia: an acute ingestion of Epsom Salt in a patient with normal renal function. Caspian Journal of Internal Medicine 9(4): 413-415. PMID 30510660
- Department of Health and Social Care. Great Britain nutrition and health claims (NHC) register, spreadsheet of 19 May 2026. Accessed 30 October 2026. gov.uk
