PMS supplements: what the evidence says

Plenty of products promise to fix PMS. Here is the honest picture. The NHS says supplements may help PMS, but there is not much evidence that they work. A 2025 systematic review of 31 trials agreed: some supplements looked helpful, but only 1 of the 31 trials was at low risk of bias.

The evidence ladder

• Calcium: some evidence, low quality. All four calcium trials in the 2025 review (776 people) reported better PMS symptoms. ACOG suggests 1,200mg a day from food and supplements together. The NHS says adults need 700mg a day, and 1,500mg or less is unlikely to cause harm.
• Vitamin B6: some evidence, but the dose is the catch. The promising trials used at least 50mg a day. UK advice is not to take more than 10mg a day in supplements unless a doctor says so, and 200mg or more a day can damage nerves. You cannot safely copy those trials at home.
• Zinc: some evidence, again at a high dose. The trials used 30mg a day or more. UK advice is not to take more than 25mg a day unless a doctor advises.
• Magnesium: weak and mixed. ACOG says it may help, but the 2025 review found too little evidence.
• Vitamin D: limited evidence for PMS. It is still worth taking in autumn and winter for your bones, as the NHS advises.
• Herbal products such as agnus castus (chasteberry): small trials, mixed results. A 2013 review found most of the 8 PMS trials favoured it, but they were small. It affects hormones, so ask a pharmacist before trying it, especially if you take the pill or other medicines.
• "Hormone balance" blends and multivitamins: no good evidence. The 2025 review found too little evidence for multivitamins, and NHS pages do not recommend them for PMS. Seed-cycling kits are similar: a few small studies, but nothing proving the phase timing matters.

Food first

You can get calcium from milk, cheese and yoghurt, soya drinks with added calcium, kale and okra, bread made with fortified flour, and tinned fish where you eat the soft bones. The NHS notes that spinach is not a good calcium source because your body cannot absorb it all.

If you decide to try one

1. Keep a symptom diary for at least 2 cycles first. The NHS suggests this anyway, and you will need a baseline to compare against.
2. Try one thing at a time, so you know what made a difference.
3. Stay within the UK limits below unless a doctor tells you otherwise.
4. Give it 2 or 3 cycles. If nothing changes, stop. Do not keep paying for something that is not helping.
5. Tell your pharmacist or GP everything you take, including herbal products.