Last updated: October 2026
Magnesium isn’t a proven treatment for PCOS, now also called PMOS. A 2025 review of six trials found magnesium alone didn’t significantly change hormones or metabolic markers, though combined mineral supplements improved insulin resistance in another review. If you take it for sleep, mood or tiredness, glycinate or citrate are the best-tolerated forms, at up to 400mg a day from supplements.
This guide covers what the research really shows, which form to choose, how much to take, how magnesium fits alongside NHS treatments, and other supplements people with PCOS ask about.
PCOS is now called PMOS
The NHS now uses the name polyendocrine metabolic ovarian syndrome (PMOS) for the condition that used to be called polycystic ovary syndrome (PCOS). The new name reflects that it affects hormones and metabolism, not just the ovaries. You’ll still see PCOS used widely, including in this guide.
Why magnesium comes up with PCOS
Many people with PCOS have insulin resistance, and magnesium is involved in how the body handles glucose and insulin. Some studies have found lower magnesium levels in people with PCOS, and in people with insulin resistance generally. PCOS is also linked with anxiety, low mood and tiredness. Magnesium contributes to normal psychological function and the reduction of tiredness and fatigue, which is why many people with PCOS consider it.
Does magnesium help PCOS? The research
| Review | What it found |
|---|---|
| Abu-Zaid, 2025 (6 controlled trials, magnesium alone) | No significant effect on sex hormones or cardiometabolic risk factors such as insulin, cholesterol or blood pressure |
| Ye, 2026 (11 controlled trials, 618 women, mineral supplements including magnesium, zinc, chromium and selenium) | Significant improvements in fasting glucose, fasting insulin and insulin resistance |
Put simply: magnesium on its own hasn’t been shown to change the core features of PCOS, but mineral supplements as a group may help insulin resistance. The trials are small and varied, so it’s best to see magnesium as one supportive part of a wider plan, alongside diet, activity and any treatment your GP recommends.
Best magnesium for PCOS
| Form | Why choose it |
|---|---|
| Glycinate (bisglycinate) | Gentle on the stomach; the usual choice for evenings, sleep and stress |
| Citrate | Well absorbed; helpful if you’re prone to constipation |
| Malate | Gentle; often taken in the daytime |
| Oxide | Cheap but poorly absorbed and more likely to loosen stools; best avoided |
PCOS trials have used various forms, and no form is proven best for PCOS itself. Choose the one you’ll tolerate and take consistently. Compare forms in magnesium glycinate vs citrate vs threonate and types of magnesium.
How much magnesium to take
The NHS says women need 270mg of magnesium a day, and that 400mg a day or less from supplements is unlikely to cause harm. PCOS trials have used varying amounts, usually well within this. Start lower, take it daily, and give it at least 8 weeks if you’re tracking changes. Too much can cause diarrhoea. See the best time to take magnesium and how long magnesium takes to work.
Our Magnesium Glycinate Sleep Complex provides 148mg of magnesium per serving from bisglycinate and citrate, as a warm evening drink.
How magnesium fits with NHS treatment
There’s no cure for PCOS, but the NHS lists treatments including the contraceptive pill or IUS for irregular periods, metformin, weight loss medicines, medicines to reduce excess hair growth, fertility treatment, and skin treatments for acne. Lifestyle changes such as a balanced diet, regular activity and, if you’re overweight, losing weight can improve symptoms.
Magnesium can sit alongside these, but shouldn’t replace them. Tell your GP or pharmacist about any supplements you take. Long-term metformin use can lower vitamin B12, which is worth asking your GP about.
Other supplements for PCOS
- Inositol: widely discussed for PCOS; research is ongoing and results are mixed. Ask your GP before trying it.
- Vitamin D: the NHS advises everyone to consider 10 micrograms a day in autumn and winter. See vitamin D in winter.
- Ashwagandha: sometimes used for stress, but avoid it if you’re trying to conceive or pregnant. See ashwagandha side effects.
- Omega-3: found in oily fish; studied for heart health in PCOS.
See also magnesium for women and magnesium for PMS.
Safety and interactions
- Check with your GP first if you have kidney disease.
- Take magnesium at least 2 hours before or 4 to 6 hours after some antibiotics, and away from osteoporosis medicines; ask your pharmacist.
- If you’re pregnant or trying to conceive, check any supplement with your GP or midwife, and avoid blends containing herbs unless advised.
- Side effects are mostly digestive: loose stools, nausea and cramps, usually at higher doses.
FAQs
Does magnesium help PCOS?
Magnesium alone hasn’t been shown to significantly change hormones or metabolic markers in PCOS. Combined mineral supplements improved insulin resistance in one review. It’s a supportive nutrient, not a treatment.
What is the best magnesium for PCOS?
Glycinate or citrate are well absorbed and well tolerated. No form is proven best for PCOS itself, so choose the one you’ll take consistently.
How much magnesium should I take for PCOS?
There’s no set dose for PCOS. The NHS says women need 270mg a day, and up to 400mg a day from supplements is unlikely to cause harm.
What does magnesium glycinate do for PCOS?
It’s a gentle form many people take for sleep, stress and tiredness, which are common in PCOS. It hasn’t been shown to treat PCOS directly.
Is PCOS now called PMOS?
Yes. The NHS now uses polyendocrine metabolic ovarian syndrome (PMOS), which reflects the hormonal and metabolic effects of the condition.
Can I take magnesium with metformin?
Generally yes, but tell your GP or pharmacist about all supplements you take, and ask about vitamin B12 if you’ve taken metformin long term.
Sources
- NHS. Polyendocrine metabolic ovarian syndrome (PMOS).
- NHS. Vitamins and minerals: magnesium.
- Abu-Zaid A et al (2025). Does magnesium affect sex hormones and cardiometabolic risk factors in patients with PCOS? A systematic review and meta-analysis. Medicina.
- Ye J et al (2026). Effectiveness of mineral supplements in reducing insulin resistance in polycystic ovary syndrome: a meta-analysis of randomized controlled trials. BMC Endocrine Disorders.
This guide is general information, not medical advice. Evopure makes the Magnesium Glycinate Sleep Complex.
