Does magnesium help PMS?
Magnesium may help PMS a little, but the evidence is limited. Small trials found 200 mg a day eased bloating and fluid retention after two months, and magnesium taken in the second half of the cycle eased premenstrual mood changes. A review also found it may reduce period cramps. It's generally safe below 350 mg a day from supplements, but check interactions with a pharmacist.
What the studies found
| Study | What they gave | What changed |
|---|---|---|
| Facchinetti et al., 1991 (32 women) | Magnesium (360 mg) three times a day, from day 15 until the period | Lower overall PMS scores and less negative mood |
| Walker et al., 1998 (38 women) | 200 mg magnesium oxide daily | No change in month one; less bloating, swelling and breast tenderness in month two |
| Cochrane review of supplements for period pain, 2016 | Various doses | Magnesium may ease cramps more than placebo, but the evidence is low quality |
These are small, older studies, so the honest summary is: possibly helpful, not proven. Magnesium seems more likely to help bloating, fluid retention and cramps than severe mood symptoms. For a comparison with calcium, B6 and chasteberry, see supplements for PMS.
Why magnesium might help
Magnesium helps muscles relax, which may explain the effect on cramps, and it's involved in how nerves and brain chemicals like serotonin and GABA work. Some older studies found lower magnesium inside cells in women with PMS, though that hasn't been firmly established.
How to take it safely
- Food first: nuts, seeds, beans, whole grains, leafy greens and dark chocolate are good sources.
- Stay under the limit: the adult upper limit for magnesium from supplements is 350 mg a day, unless a doctor advises otherwise. Food magnesium doesn't count toward it.
- Expect a delay: trials saw effects in the second cycle, so give it two to three months.
- Forms: magnesium oxide was used in one trial; citrate and glycinate are often better absorbed and may be gentler on the stomach, but haven't been compared for PMS.
- Side effects: diarrhea, nausea and stomach cramps, especially at higher doses.
You have kidney disease (magnesium can build up), or take bisphosphonates, certain antibiotics (tetracyclines or quinolones), diuretics, or acid-reducing medicines, which can interact with magnesium or need to be spaced apart. If PMS is severe, affects your daily life, or you feel hopeless, see a doctor rather than relying on supplements.
Magnesium and mood before your period
If your main PMS symptom is low mood, irritability or anxiety, magnesium might take a small edge off, but it's not a substitute for treatment that works. Regular exercise, steady sleep and, for severe symptoms, SSRIs have stronger evidence. See PMS mood swings and how to stop PMS mood swings.
Rate your mood and symptoms every day for one cycle before you start, then for two or three cycles on magnesium. Comparing the luteal weeks side by side shows whether it's actually helping.
Frequently asked questions
When should I take magnesium for PMS?
Studies used it either daily or from mid-cycle until the period. Daily is simpler. Taking it in the evening may help if it relaxes you.
Does magnesium help period cramps?
It may. A Cochrane review found some evidence magnesium eases period pain more than placebo, though the studies were low quality.
Which magnesium is best for PMS?
No form has been shown to be best for PMS. Citrate and glycinate are commonly chosen because they're well absorbed and gentler on the stomach.
Can I take magnesium with the pill?
There's no known major interaction, but ask a pharmacist to check against all your medicines.
Sources
- Facchinetti F et al. Oral magnesium successfully relieves premenstrual mood changes. Obstet Gynecol (1991)
- Walker AF et al. Magnesium supplementation alleviates premenstrual symptoms of fluid retention. J Womens Health (1998)
- Pattanittum P et al. Dietary supplements for dysmenorrhoea. Cochrane Database Syst Rev (2016)
- NIH Office of Dietary Supplements: Magnesium Fact Sheet for Health Professionals
This page is for information only and isn鈥檛 medical advice. If something worries you, please talk to a doctor.
Keep reading
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