A magnesium tallow balm is a cosmetic: a magnesium salt stirred into fat. The evidence that skin absorbs enough magnesium to change the levels in your blood is thin, and the studies behind it are small. Gröber and colleagues reviewed them for Nutrients in 2017. Their abstract calls the promotion of transdermal magnesium "scientifically unsupported," and I read the evidence the same way. So the balm isn't a supplement, and it isn't a sleep aid.
None of our five balms contains magnesium, and this post explains why, from the skin studies to the salt itself. For dry skin, it's Bare Silk ($34 as of October 5, 2026). It's the Unscented original: grass-fed suet tallow with meadowfoam seed oil and organic jojoba oil, plus vitamin E and organic arrowroot. There's no water in the jar.
Magnesium matters in the body, and the NIH Office of Dietary Supplements calls it a cofactor in more than 300 enzyme systems. Muscle and nerve function are on that list. The question here is delivery, and it's narrower: whether a jar on your skin can get magnesium where it's needed.
What is magnesium oil?
Magnesium oil is a brine, magnesium chloride dissolved in water, with no oil in it despite the name. It's sold as a spray. Kass and colleagues, writing in PLoS One in 2017, put makers' directions at 5 to 30 sprays a day. Creams run 2 to 4 teaspoons. Followed to the letter, those directions put 75 to 400 mg of magnesium on your skin each day.
The salt is ordinary. The FDA lists magnesium chloride as a food ingredient, used as a flavoring agent and as a nutrient supplement. Its rule calls the salt deliquescent. That's a chemist's word for a solid that pulls water out of the air until it dissolves. This salt likes water.
How the spray feels on skin is mostly anecdote, and I couldn't find a study that measured it. Reports vary. Some people describe a tingle or a sting after spraying, and others feel nothing at all. The Kass team logged no adverse reactions to its cream. Whatever you try, keep it on intact skin, well away from cuts and cracked patches.
Does skin absorb magnesium?
Very little, as far as the studies can tell, and the reason is the skin's job of keeping things out. Kass and colleagues place that barrier in the stratum corneum, the skin's outermost layer. Gröber's review explains the chemistry. Only fat-loving substances cross that layer in meaningful amounts, and magnesium in a chloride solution sits as charged ions that can't. The likeliest way in is through hair follicles and sweat glands. Together they cover only 0.1% to 1% of the skin's surface, a narrow door for a salt.
Most of the human studies are small, and they don't agree.
| Study, as Gröber reports it | What people used | What it found |
|---|---|---|
| Spa bath study | 8 people, two hours in spa water | No change in plasma magnesium |
| Israeli army lotion trial | 34 people, a magnesium-rich lotion or placebo, three days | No difference from placebo |
| Epsom salt baths | 19 people, 12 minutes a day for a week | Rises in 16 of 19, published online, not in a journal |
| Kass and colleagues, 2017 | 25 people, a magnesium cream or placebo, two weeks | No significant rise overall |
In the Kass pilot, adults spread a cream carrying 56 mg of magnesium a day, or a placebo cream, on their skin for two weeks. Twenty-four finished. Blood magnesium in the cream group rose from 0.82 to 0.89 mmol/L, which the authors call clinically relevant. It reached statistical significance only in the 20 non-athletes. Urine levels didn't move significantly either, and the team calls for larger trials at higher doses. Serum is a rough window anyway. Less than 1% of the body's magnesium sits there, the ODS says, and the body keeps that level under tight control.
Gröber's team ends on a plain line: they "cannot yet recommend" transdermal magnesium.
Does magnesium cream help with sleep or cramps?
The sleep and cramp claims borrow from pill trials, and even those results are mixed. Mah and Pitre pooled three randomized trials of oral magnesium in 151 older adults for a 2021 review in BMC Complementary Medicine and Therapies. People fell asleep about 17 minutes faster than on placebo, and total sleep time didn't improve significantly. The certainty was low to very low. The authors called the literature "substandard" for doctors making recommendations, then noted that oral magnesium is cheap and widely available. On that basis, they say the trials may support pills for insomnia symptoms.
Cramps look weaker still. A 2020 Cochrane review by Garrison and colleagues covered 11 trials and 735 people, and ten of the trials gave magnesium by mouth. For older adults, magnesium was unlikely to cut how often cramps came or how bad they got. The pregnancy trials didn't agree. The ODS does list cramps among the signs of a worsening deficiency, yet it says healthy people rarely get there from diet alone. The kidneys hold it back.
These trials gave magnesium by mouth or by vein, never on skin. Cramps that keep waking you, or sleep that won't come, belong with your doctor. I make the balm I'm about to recommend. It's cosmetic care, not a treatment, and your provider's plan comes first.
Why don't we pour a magnesium balm?
At my bench, every candidate ingredient faces the same first test: where it lives in a jar with no water. Magnesium chloride fails it. It dissolves in water and won't dissolve in fat, so dry crystals stirred into warm tallow stay crystals, a grit suspended in the balm. That's the same chemistry that keeps it out of the skin's top layer.
The other route is to dissolve the salt in water first and blend that brine into the fat. Oil and water separate. The jar then needs an emulsifier to hold them together and a preservative system to keep microbes from growing. By then it's a lotion with tallow in it. That's the jar we've chosen not to make, and our post on why there's no water in our balms covers the trade.
The salt isn't the problem. In a balm, though, it isn't doing what the word magnesium on a label suggests.
If you came for sleep or cramps, none of our jars is built for that job, and I'd rather tell you than sell you one. Our balms hold no magnesium. For dry, tight skin, it's the unscented jar I named up top, smoothed in a thin layer over damp skin after a shower. It holds in the water that's already on your skin, which is the job a balm does best.
Start with Bare Silk ($34), five ingredients and sixty days to disagree.
Questions we hear
Does transdermal magnesium work?
The evidence that magnesium on skin raises the levels in your blood is thin, and the studies are small. A 2017 review by Gröber and colleagues in Nutrients couldn't recommend it. A 2017 pilot of 25 adults by Kass and colleagues saw a blood rise that reached statistical significance only in a subgroup of non-athletes. Skin's top layer keeps charged ions like magnesium out, which is why any effect looks small.
Does magnesium cream help you sleep?
A 2021 review by Mah and Pitre pooled three randomized trials of oral magnesium in 151 older adults, and none of the three used a cream. People fell asleep about 17 minutes faster than on placebo. Total sleep time didn't improve significantly, and the authors rated the evidence low to very low certainty. A cream's sleep claim leans on studies of a pill.
Is magnesium oil an oil?
No, it's a brine: magnesium chloride dissolved in water, with no oil in it despite the name. It's sold as a spray. A 2017 paper by Kass and colleagues puts makers' directions at 5 to 30 sprays a day. The FDA lists the salt as a food ingredient. Some people say the spray tingles or stings, and others feel nothing at all.
Can you put magnesium in a tallow balm?
You can stir the salt into melted tallow, but the crystals won't dissolve in fat and sit in the balm as grit. Dissolving it first means adding water. The jar then needs an emulsifier to hold water and fat together and a preservative system to keep microbes from growing. That's a lotion. None of our five balms contains magnesium, and none contains water.
Does magnesium help leg cramps?
For older adults with cramps that have no clear cause, the trials say probably not. A 2020 Cochrane review by Garrison and colleagues covered 11 trials and 735 people, and ten of the trials gave magnesium by mouth. In older adults, it was unlikely to cut how often cramps came or how bad they got. Pregnancy trials didn't agree. None of the 11 tested a cream or a spray.
Is there a tallow magnesium lotion recipe?
People make one by dissolving magnesium chloride flakes in a little water and stirring that into whipped tallow. The water is the catch: it puts the lotion under the spoilage rules a no-water balm escapes, so it needs a preservative and a short life in the fridge, and the magnesium itself can sting on broken or freshly shaved skin. If you want to try it, keep the batch small, keep it cold and patch-test first. We don't publish one, for the reasons above.
Go deeper
Start with the beef tallow for skin guide, the pillar post for everything here. For magnesium from food, read eat your hydration. Our skin barrier primer explains what that top layer is built from, and cream, balm, lotion or butter sorts jars by what's in them. Magnesium is one of several things we tested and left out; the full list is in ingredients we looked at and left out.
Sources
- Gröber U, Werner T, Vormann J, Kisters K (2017). Myth or reality, transdermal magnesium? Nutrients, volume 9, issue 8, article 813, an open access review from MDPI.
- Kass L and colleagues (2017). Effect of transdermal magnesium cream on serum and urinary magnesium levels in humans: a pilot study. PLoS One, volume 12, issue 4, e0174817, Public Library of Science.
- NIH Office of Dietary Supplements (2026). Magnesium, fact sheet for health professionals, updated January 6, 2026, read October 5, 2026. National Institutes of Health.
- Garrison SR, Korownyk CS, Kolber MR, Allan GM, Musini VM, Sekhon RK, Dugré N (2020). Magnesium for skeletal muscle cramps, published September 21, 2020. Cochrane Database of Systematic Reviews, review CD009402, read as the plain language summary and authors' conclusions.
- Mah J, Pitre T (2021). Oral magnesium supplementation for insomnia in older adults: a systematic review and meta-analysis. BMC Complementary Medicine and Therapies 21:125.
- US Food and Drug Administration, Code of Federal Regulations, title 21 (2026). Section 184.1426, magnesium chloride. eCFR, up to date as of September 30, 2026.
Brian is the founder of Craft Tallow, a small-batch tallow skincare line shipped from Cottonwood Heights, Utah, built on 100% grass-fed suet. Questions? Reply to any email from us; it lands with him.