Supplements, tested
Does Magnesium Spray Work?
Reviewed by a qualified clinician · analysed at UKAS-accredited UK labs (ISO 15189)
Last reviewed October 20265 min read
Every Helvy guide is written by our health editors, then checked by a qualified clinician before it goes live and re-checked as the science moves. We name clinical roles, not individuals, until each reviewer has agreed to be credited publicly. This is wellness guidance to help you understand your own data, not a diagnosis.
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Probably not much. A 2017 review found no good evidence that magnesium gets through the skin in useful amounts. The one small trial of a cream saw only a slight rise. If you think you are low, a blood test is a better first step. Food or a gentle tablet is a better fix.
Check if you are low first. Build your test →As of October 2026. “Is topical magnesium really useless?” is one of the busiest questions on Reddit's supplements forum this month. Most people asking have the same story. Tablets upset their stomach, so they tried a spray instead. Here is what the evidence says, and what to do if you still think you are low.
1. Does magnesium spray get through your skin?
Your skin is built to keep things out. That is its whole job.
Magnesium spray, often sold as magnesium oil, is magnesium chloride dissolved in water. It is not really an oil. It just feels slippery. The pitch is simple: rub it on and you skip your gut, so no upset stomach and near total absorption.
The problem is that magnesium is a charged particle, and charged particles cross the outer layer of skin very poorly. A little may slip in through hair follicles and sweat glands. Nobody has shown it is enough to change your body's stores.
2. What have the studies actually found?
Very little, and most of it is small. In 2017 a team of German researchers reviewed everything published on magnesium through the skin. Their verdict was blunt.
“The propagation of transdermal magnesium is scientifically unsupported.”
— Gröber and colleagues, Nutrients, 2017
The best direct test is a small pilot trial from the same year. Twenty five adults used either a magnesium cream giving 56mg a day or a dummy cream, for two weeks. Blood magnesium rose from 0.82 to 0.89 mmol/L in the cream group, but across the whole group that was not statistically significant. Only a subgroup of non-athletes showed a clear rise.
For scale, 56mg is about a fifth of what a woman needs in a day. The trial's authors called it a pilot and asked for bigger studies. Those have not arrived.
So the honest answer is that spray is unproven, not proven useless. If it helps you relax at bedtime, the massage may be doing the work. It is unlikely to fix a real shortfall.
3. Can a blood test tell if you need magnesium?
It can tell you some things, and you should know its limits. A standard test reads serum magnesium, which is the magnesium floating in the liquid part of your blood.
That is a tiny slice of the total. A 2012 review in the Clinical Kidney Journal puts about 99% of your magnesium in bone, muscle and other tissue. Your body works hard to keep the blood level steady, drawing on those stores when it needs to.
So read the result this way. A low reading is meaningful, because your stores have usually run down before the blood level drops. A normal reading is reassuring but does not fully rule out low stores. Pair it with how you feel, such as cramps, twitches or poor sleep. Our guide to normal magnesium levels shows where the UK range sits.
Do not expect a retest to prove a spray works. The blood level barely moves even when stores change, so a test is best used before you start, not as a scoreboard.
4. What if magnesium tablets upset your stomach?
This is the real reason most people turn to spray, and there are better fixes. Start with food. The NHS lists spinach, nuts and wholemeal bread as good sources.
The NHS says you should be able to get all the magnesium you need from a varied and balanced diet. That is 300mg a day for men and 270mg for women aged 19 to 64.
If you do take a tablet, the form matters. Citrate and oxide pull water into the bowel and are the most likely to loosen it. Glycinate is gentler for many people. Our guide to which magnesium to take compares them.
Two simple tricks help too. Split the dose across the day, and take it with food. Keep supplements to 400mg or less a day, the level the NHS calls unlikely to cause harm. Our guide on how much magnesium is too much explains the dose maths.
Before any of that, check you need it. The signs of low magnesium overlap with low vitamin D, low B12 and thyroid problems. That is why tiredness is worth testing properly. Helvy's General Energy & Wellness panel (£149) measures magnesium alongside those markers from one home finger-prick sample. The energy and fatigue hub covers the wider picture.
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Find out if you were low before you buy another bottle
Helvy's home blood tests report your magnesium with the markers that cause the same symptoms. Results in around five working days from UKAS-accredited UK labs.
Frequently asked questions
Does magnesium spray work?
There is no good evidence that it raises your magnesium in a useful way. A 2017 review called skin absorption scientifically unsupported. One small trial of a cream saw only a slight rise in blood magnesium.
Is magnesium oil better than tablets?
No study shows it works better. Tablets are proven to raise magnesium. If they upset your stomach, try a gentler form like glycinate, a smaller split dose, or taking it with food.
Can a blood test show if magnesium spray is working?
Not reliably. Blood holds only a tiny share of your magnesium and the level stays steady even as stores change. A test is most useful before you start, to see if you were low.
Why does magnesium spray tingle?
Magnesium chloride is a salty solution, and many people find it stings or itches, especially on shaved or broken skin. That feeling is the salt on your skin, not a sign that it is being absorbed.