Last updated: October 2026
Magnesium isn’t a treatment for PCOS, now called PMOS. Studies suggest women with PCOS often have slightly lower magnesium levels, and a few small trials found changes in insulin resistance, but a 2025 meta-analysis found magnesium alone didn’t change hormones or metabolic markers. If you take it, glycinate or citrate are gentle choices, up to 400mg a day.
This guide covers what the research really shows, symptom by symptom, whether people with PCOS are low in magnesium, which form to choose, how much to take, how it fits with NHS treatment and metformin, and what to know if you’re trying to get pregnant.
Straight answer first
Magnesium Glycinate Sleep Complex
magnesium won’t treat PCOS (PMOS), and we won’t tell you it does. If you want a gentle evening magnesium, our Magnesium Glycinate Sleep Complex gives 290mg of magnesium per serving from bisglycinate and citrate, with glycine, L-theanine, chamomile, passionflower, hops and oat straw, as a berry-flavoured powder sweetened with stevia. It’s vegan, made in the UK and for adults only. We don’t recommend our products during pregnancy or breastfeeding.
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View productPCOS 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. It’s the same condition, so an existing PCOS diagnosis and treatment still stand, and you’ll see both names for a while, including in this guide. Read more in PCOS has a new name: what PMOS means.
Why magnesium comes up with PCOS
The NHS says the cause of PMOS is unknown, but it may be to do with hormones such as insulin and testosterone not working properly. Blood tests for PMOS can include a check for insulin resistance. Magnesium is involved in how the body handles glucose and insulin, which is why researchers have looked at it in PCOS.
PCOS is also linked with tiredness, anxiety and low mood. Magnesium contributes to normal psychological function and to a reduction of tiredness and fatigue, which is another reason many people with PCOS consider it. That’s about magnesium in general, not a treatment for PCOS. For more on the symptoms, see hormonal imbalance symptoms in women.
Are people with PCOS low in magnesium?
Possibly, though the picture isn’t clear-cut. A 2021 meta-analysis of 8 studies (about 2,000 women) found slightly lower blood magnesium in women with PCOS than in women without it, but the studies varied a lot, and the gap was clearest in women who were overweight. In a Chinese study of 1,000 women with PCOS, those with the lowest blood magnesium were more likely to have insulin resistance and had higher testosterone.
A 2019 review also found that women with PCOS were more likely to eat fewer magnesium-rich foods. These are observational studies, so they show a link, not that low magnesium causes PCOS or that topping it up fixes it. If you’re worried you’re low, see signs of magnesium deficiency and speak to your GP.
Does magnesium help PCOS? The research
| Study | What it found |
|---|---|
| Abu-Zaid, 2025 (meta-analysis, 6 controlled trials, magnesium alone) | No significant effect on sex hormones or cardiometabolic risk factors such as insulin, cholesterol or blood pressure |
| Ye, 2026 (meta-analysis, 11 controlled trials, 618 women, mineral supplements including magnesium, zinc, chromium and selenium) | Lower fasting glucose, fasting insulin and insulin resistance with minerals as a group; mixed effects on cholesterol |
| Li, 2022 (systematic review, 9 trials, 363 women) | Magnesium alone made no significant difference to blood sugar, blood fats or inflammation; combinations with other nutrients showed improvements |
| Shahmoradi, 2024 (40 women, 250mg magnesium oxide for 2 months) | Lower insulin and insulin resistance than placebo; no difference in weight or blood pressure |
| Farsinejad-Marj, 2020 (60 women, 250mg magnesium oxide for 8 weeks) | No effect on blood sugar or cholesterol; a small fall in BMI compared with placebo |
| Gholizadeh-Moghaddam, 2023 (64 women, 250mg magnesium oxide for 10 weeks) | No effect on testosterone, excess hair or sleep quality |
| Jaripur, 2022 (same 64 women) | Better quality-of-life scores, including energy and emotional wellbeing; no effect on acne, hair loss or abnormal bleeding |
Put simply: magnesium on its own hasn’t been shown to change the core features of PCOS. One small trial saw a change in insulin resistance and another didn’t, and mineral supplements as a group look more promising for insulin resistance. The trials are small, short and mostly from one country, so treat magnesium as one supportive part of a wider plan, alongside diet, activity and any treatment your GP recommends.
A note on the combination trials: some of the most-quoted positive trials of magnesium combined with zinc, calcium and vitamin D, or with vitamin E, come from one research group. One of those papers has since been retracted and another carries an expression of concern from its journal, so we give them little weight here.
Magnesium and PCOS symptoms
Most people searching for magnesium for PCOS have a particular symptom in mind. Here’s what the PCOS trials above found for each one.
| Symptom | What PCOS trials of magnesium found |
|---|---|
| Insulin resistance | Mixed: one trial found a change, another didn’t, and the 2025 meta-analysis found no overall effect of magnesium alone |
| Weight | One trial found a small BMI change over 8 weeks (about 0.3 points), not meaningful weight loss on its own |
| Testosterone and excess hair | No significant effect compared with placebo |
| Acne and hair loss | No significant effect |
| Periods | No significant effect on abnormal bleeding or infrequent periods compared with placebo |
| Sleep quality | No significant effect in the one PCOS trial that measured it |
| Quality of life, energy and mood | One trial found better quality-of-life scores than placebo |
If weight is your main concern, see magnesium for weight loss for the wider evidence. For skin, stress acne covers other triggers. If you snore or wake unrefreshed, mention it to your GP: obstructive sleep apnoea is more common with PMOS (see sleep apnoea). For period pain and premenstrual symptoms, see magnesium for PMS.
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 | Used in most PCOS trials because it’s cheap; less well absorbed and more likely to loosen stools |
Most of the PCOS trials above used 250mg of magnesium oxide, and no form is proven best for PCOS itself. Choose the one you’ll tolerate and take consistently. For most people that’s magnesium glycinate, or magnesium citrate if constipation is an issue. Compare forms in magnesium glycinate vs citrate vs threonate, magnesium oxide and types of magnesium.
How much magnesium to take
The NHS says women aged 19 to 64 need 270mg of magnesium a day, and that 400mg a day or less from supplements is unlikely to cause harm. Higher doses can cause diarrhoea. The PCOS trials used 250mg of magnesium oxide a day for 8 to 10 weeks. Start lower, take it daily, and give it at least 8 weeks if you’re tracking changes.
Food counts too. Spinach, nuts and wholemeal bread are good sources, and our list of foods high in magnesium has more. See the best time to take magnesium and how long magnesium takes to work.
Magnesium and zinc for PCOS
Magnesium is often paired with zinc, calcium or vitamin D in PCOS supplements. The 2026 meta-analysis of mineral supplements found improvements in insulin resistance with minerals as a group, and the 2022 review found combinations did better than magnesium alone. But the combination trials are few, small and, as noted above, partly from one research group with retracted work. If you take a combination, keep within the NHS upper levels for each nutrient. See zinc, magnesium vs zinc and magnesium and vitamin D.
How magnesium fits with NHS treatment
There’s no cure for PMOS, but the NHS lists treatments including the combined pill, progestogen-only pill or IUS for irregular periods, metformin, weight loss medicines if you’re overweight, spironolactone or eflornithine for excess hair, clomifene for fertility, and skin treatments for acne. Eating a balanced diet, exercising regularly and, if you’re overweight, losing weight can help symptoms.
NICE published its first draft guideline for PMOS in July 2026. It proposes an annual review for everyone with PMOS, because of the links with type 2 diabetes, heart disease, sleep apnoea, fatty liver disease, mental health problems and pregnancy complications.
Magnesium can sit alongside these, but shouldn’t replace them. Tell your GP or pharmacist about any supplements you take.
Metformin, vitamin B12 and magnesium
Metformin is one of the most common medicines for PCOS. The NHS lists vitamin B12 deficiency, which can make you feel very tired, as a common side effect. If you’ve taken metformin for a while and feel unusually tired, ask your GP about a B12 test rather than assuming it’s low magnesium. See vitamin B12 deficiency symptoms and vitamin B12 supplements.
The NHS also says some medicines, herbal remedies and supplements may not mix well with metformin, so tell your doctor or pharmacist about anything you take, magnesium included.
Trying to conceive and pregnancy
If you’re trying to get pregnant, the supplement that matters most is folic acid. The NHS recommends 400 micrograms a day, ideally from 3 months before you get pregnant until 12 weeks of pregnancy. Some people need a higher 5mg dose on prescription, including those with diabetes, so ask your GP. The NHS also recommends 10 micrograms of vitamin D a day in pregnancy, at least from October to March.
Magnesium needs in pregnancy are covered in magnesium in pregnancy. Check any supplement with your GP or midwife, and avoid blends containing herbs unless advised. We don’t recommend our products during pregnancy or breastfeeding. Ashwagandha, sometimes sold for PCOS, should be avoided if you’re pregnant or trying to conceive (see ashwagandha for PCOS).
Other supplements for PCOS
- Inositol: the most studied supplement for PCOS, though results are mixed. See our guide to inositol for PCOS for the evidence, doses used in studies and who should check first.
- Berberine: sometimes compared with metformin; see berberine for PCOS: evidence and safety before trying it, especially if you take other medicines.
- 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 supplements for women over 40.
Our Magnesium Glycinate Sleep Complex
Our Magnesium Glycinate Sleep Complex provides 290mg of magnesium per serving from magnesium bisglycinate and magnesium citrate, two gentle, well-absorbed forms. It also contains glycine, L-theanine, chamomile, passionflower, hops and oat straw, in a berry-flavoured powder sweetened with stevia that you mix into a drink in the evening.
Magnesium contributes to normal psychological function, normal functioning of the nervous system and a reduction of tiredness and fatigue. It isn’t a treatment for PCOS or PMOS, and it’s not a substitute for anything your GP prescribes. One serving is well within the NHS guide of 400mg a day or less from supplements. It’s vegan, made in the UK and for adults (18+) only. We don’t recommend our products during pregnancy or breastfeeding.
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. See magnesium side effects.
For UK daily amounts for women and the supplement limit, see how much magnesium per day for a woman.
Sources 16
- NHS. Polyendocrine metabolic ovarian syndrome (PMOS).
- NHS. Vitamins and minerals: magnesium.
- NHS. Metformin.
- NHS. Vitamins, supplements and nutrition in pregnancy.
- The Pharmaceutical Journal (2026). NICE issues first UK guidance for PMOS treatment.
- 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. PMID 40005397.
- 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. PMID 41580698.
- Li R et al (2022). The effect of magnesium alone or its combination with other supplements on the markers of inflammation, OS and metabolism in women with PCOS: a systematic review. Frontiers in Endocrinology. PMID 35992132.
- Babapour M et al (2021). Associations between serum magnesium concentrations and polycystic ovary syndrome status: a systematic review and meta-analysis. Biological Trace Element Research. PMID 32812171.
- Luo X et al (2021). Associations of serum magnesium with insulin resistance and testosterone in women with polycystic ovary syndrome. Frontiers in Endocrinology. PMID 34248844.
- Hamilton KP et al (2019). Insulin resistance and serum magnesium concentrations among women with polycystic ovary syndrome. Current Developments in Nutrition. PMID 31696157.
- Shahmoradi S et al (2024). The effect of magnesium supplementation on insulin resistance and metabolic profiles in women with polycystic ovary syndrome: a randomized clinical trial. Biological Trace Element Research. PMID 37393389.
- Farsinejad-Marj M et al (2020). Clinical and metabolic responses to magnesium supplementation in women with polycystic ovary syndrome. Biological Trace Element Research. PMID 31960275.
- Gholizadeh-Moghaddam M et al (2023). Effect of magnesium supplementation in improving hyperandrogenism, hirsutism, and sleep quality in women with polycystic ovary syndrome: a randomized, placebo-controlled clinical trial. Health Science Reports. PMID 36620514.
- Jaripur M et al (2022). The effects of magnesium supplementation on abnormal uterine bleeding, alopecia, quality of life, and acne in women with polycystic ovary syndrome: a randomized clinical trial. Reproductive Biology and Endocrinology. PMID 35918728.
- Retraction note (2023). Magnesium-zinc-calcium-vitamin D co-supplementation improves hormonal profiles… in women with PCOS. Biological Trace Element Research. PMID 36418637.
This guide is general information, not medical advice. Evopure makes the Magnesium Glycinate Sleep Complex.
