This article is for general information only and is not medical advice. If you have a health condition, take prescribed medication or are pregnant, speak to your doctor or pharmacist before changing your supplements.
The short answer
There is no good evidence that magnesium stops night sweats, or that low magnesium causes them. One early study looked promising, but the larger trial that followed found magnesium worked no better than a placebo for hot flushes. Night sweats have several well-known causes, and it is more useful to work through those. If yours are regular, drenching or come with other symptoms, see your GP.
What the trials found
The idea comes mainly from research into menopausal hot flushes in women who had been treated for breast cancer, a group who often can’t take hormone treatment.
- A small pilot study with no placebo group reported fewer and milder hot flushes in women taking magnesium oxide.
- The placebo-controlled trial that followed, published in 2015, tested two doses of magnesium oxide in 289 women. Neither dose reduced hot flushes more than the placebo did.
This is a common pattern in supplement research. Early results without a comparison group look good, then fade when tested properly. We haven’t found trials of magnesium for night sweats from other causes.
Does sweating use up your magnesium?
Sweat contains a little magnesium, but the amounts are small compared with what you get from food. Heavy sweating is not a recognised cause of magnesium deficiency in people eating a normal diet. An earlier version of this article described a cycle in which sweating lowers magnesium, which then causes more sweating. There isn’t evidence for that, and we have removed it.
What does cause night sweats
The NHS lists the most common causes as:
- menopause symptoms (hot flushes)
- anxiety
- some medicines, including certain antidepressants, steroids and painkillers
- low blood sugar
- alcohol or drug use
- hyperhidrosis, a harmless condition that causes excessive sweating
Sometimes no cause is found. A warm bedroom, heavy bedding and synthetic nightwear are worth ruling out first.
Where magnesium might fit
Some people take magnesium in the evening because they find it relaxing, and trials suggest it may help some people fall asleep a little sooner, although that evidence is weak too. If you sleep better you may be less bothered by night-time waking in general. That is different from treating the sweats themselves.
If you want to try it, the NHS says 400 mg or less a day from supplements is unlikely to cause harm, and higher doses can cause diarrhoea. Give it a few weeks. If nothing changes, there is no reason to keep taking it for this.
Be cautious with sleep blends that combine magnesium with melatonin or herbs and claim to end night sweats. Those claims aren’t supported by trials.
Things that can help
- Keep the bedroom cool and use layers of light, breathable bedding.
- Cut back on alcohol, caffeine and spicy food in the evening.
- If you think a medicine is responsible, ask your GP or pharmacist. Don’t stop it yourself.
- For menopausal symptoms, your GP can talk you through the options, including HRT and non-hormonal treatments.
When to see your GP
The NHS advises seeing a GP if:
- you have night sweats regularly that wake you or worry you
- you also have a very high temperature, or feel hot, cold or shivery, or have a cough or diarrhoea
- you have night sweats and are losing weight for no reason
If you regularly wake with soaking wet sheets, get it checked.
See how magnesium relates to other nutrients
If you do take magnesium, it is worth knowing how it interacts with the other supplements in your routine. Tap magnesium on our free Mineral Interaction Wheel to see what it works with and what it may compete with. Our magnesium side effects guide covers dose, form and timing.
Sources
- NHS. Night sweats.
- Park H, et al. North Central Cancer Treatment Group N10C2 (Alliance): a double-blind placebo-controlled study of magnesium supplements to reduce menopausal hot flashes. Menopause, 2015.
- Park H, et al. A pilot phase II trial of magnesium supplements to reduce menopausal hot flashes in breast cancer patients. Supportive Care in Cancer, 2011.
- NHS. Vitamins and minerals: Others (magnesium).