No EU-authorised health claim mentions cramps. A 2020 Cochrane review looked at 11 randomised trials with 735 participants. In older adults with cramps of no known cause (5 trials, 271 people), magnesium probably does not meaningfully prevent leg cramps: cramps were no less frequent or severe than with placebo. The certainty of this evidence is moderate. In pregnancy (5 trials, 408 women), results were inconsistent and the authors are very uncertain.
Magnesium contributes to normal muscle function and to electrolyte balance. These are authorised claims, and they say nothing about cramps. If cramps disturb your sleep, last longer than 10 minutes, or come with numbness or swelling in the legs, the NHS advises seeing a GP. Pregnant women and people who take medicines should ask a doctor or pharmacist first.
Probably not in a meaningful way, according to the Cochrane review. The review by Garrison and colleagues (2020) pooled 5 trials with 271 older adults who had leg cramps of no known cause. Magnesium did not reduce how often the cramps came or how severe they were, compared with placebo. The authors rated the certainty as moderate.
The review covered 11 randomised trials with 735 participants in total. One small trial of 29 people looked at liver cirrhosis. The authors call for more research in pregnancy and in cramps linked to exercise or disease. An earlier 2012 version of the same review, with 7 trials and 406 participants, reached the same conclusion for older adults.
Side effects were compared too. Serious side effects were rare and similar to placebo. Mild side effects, mostly diarrhoea and nausea, were more common with magnesium: about 11–37% of people, against 10–14% with placebo. The certainty of this finding is low.
The evidence is very uncertain. The Cochrane review found 5 trials with 408 pregnant women. Their results were inconsistent, so the authors did not combine them, and all 5 trials had a high risk of bias.
The NHS lists late pregnancy as one of the causes of leg cramps. If you are pregnant, talk to your doctor or midwife before taking any supplement, including magnesium.
The NHS lists several causes, and some cramps have no known cause at all:
The NHS advises seeing a GP in three situations:
If you take statins or diuretics, these medicines are on the NHS list of causes. Ask your doctor or pharmacist about the cramps, and before adding magnesium or any other supplement.
In the EU, magnesium has 10 authorised health claims, and none of them mentions cramps. They are listed in Commission Regulation (EU) No 432/2012. Four of them are:
A claim about normal muscle function is not a claim about cramps.
No form of magnesium has been shown to work better than another for cramps. The differences between forms are explained in the guide magnesium types.
Stivits sells four magnesium products, one of them in two pack sizes. All are made in Latvia and sold by HYPERPHARM OÜ, Tallinn. The figures come from the product pages.
| Product | Magnesium per daily serving | Vitamin B6 per daily serving | Daily serving | Pack lasts |
|---|---|---|---|---|
| Magnesium bisglycinate 300 mg + B6, 180 capsules | 300 mg | 7.5 mg | 3 capsules | 60 days |
| Magnesium citrate 400 mg + B6, 120 tablets | 400 mg | 10 mg | 2 tablets | 60 days |
| Magnesium citrate 400 mg + B6, 240 tablets | 400 mg | 10 mg | 2 tablets | 120 days |
| Magnesium Malate 2000mg, 90 tablets | 230 mg per tablet; 230–460 mg on 1–2 tablets | 2.5 mg per tablet | 1–2 tablets | 45–90 days |
| Magnesium 500 mg + B6, 90 capsules | 500 mg (as magnesium oxide), 133.3 % of the nutrient reference value (NRV) | 5 mg | 1 capsule | 90 days |
The 2000 mg in the malate product name is not the amount of magnesium. One tablet gives 230 mg of magnesium.
For the price per day of each product, see the Stivits budget page.
Pumpkin seeds, almonds and spinach all contain magnesium. Figures from the NIH Office of Dietary Supplements:
| Food | Portion | Magnesium |
|---|---|---|
| Pumpkin seeds, roasted | 1 oz (28 g) | 156 mg |
| Almonds, dry roasted | 1 oz (28 g) | 80 mg |
| Spinach, boiled | ½ cup | 78 mg |
The NIH recommended daily amount for adults is 400 mg for men aged 19–30 and 420 mg from age 31. For women it is 310 mg aged 19–30 and 320 mg from age 31. A varied and balanced diet and a healthy lifestyle are important.
Pregnant women and people who take medicines, including statins and diuretics, should talk to a doctor or pharmacist before taking magnesium. The same applies to anyone whose cramps match the NHS warning signs: they disturb sleep, last longer than 10 minutes, or come with numbness or swelling in the legs.
Probably not in a meaningful way. A 2020 Cochrane review pooled 5 trials with 271 older adults who had leg cramps of no known cause. Magnesium did not reduce how often or how severely the cramps came, compared with placebo. The certainty of this evidence is moderate.
No form of magnesium has been shown to work better than another for cramps, and no EU-authorised health claim mentions cramps. If cramps disturb your sleep or last longer than 10 minutes, see a GP.
In older adults, the research does not show a meaningful effect. A 2020 Cochrane review found that magnesium probably does not meaningfully prevent leg cramps of no known cause in older adults, with moderate certainty. For cramps in pregnancy the evidence is very uncertain. No EU-authorised health claim mentions cramps.
The Cochrane review found 5 trials with 408 pregnant women; their results were inconsistent, all had a high risk of bias, and the authors are very uncertain whether magnesium helps. The NHS lists late pregnancy as a common cause of leg cramps. Talk to your doctor or midwife before taking any supplement.
No. Magnesium has 10 authorised health claims in Commission Regulation (EU) No 432/2012, and none mentions cramps. The closest is 'Magnesium contributes to normal muscle function', which is not a claim about cramps.
The NHS lists ageing, muscle strain during exercise (worse in hot or humid weather), late pregnancy, certain medicines such as statins and diuretics, dehydration, and liver disease from heavy alcohol use. Some cramps have no known cause.
The NHS advises seeing a GP if the cramps disturb your sleep, if you have numbness or swelling in your legs, or if a cramp lasts longer than 10 minutes.
Ask your doctor or pharmacist first. The NHS lists statins and diuretics among the causes of leg cramps, so the cramps themselves are worth discussing with the person who prescribed the medicine.
In the Cochrane review, serious side effects were rare and similar to placebo. Mild side effects, mostly diarrhoea and nausea, were more common with magnesium: about 11–37% of people, against 10–14% with placebo. The certainty of this finding is low.
One tablet of Stivits Magnesium Malate 2000mg gives 230 mg of magnesium and 2.5 mg of vitamin B6. The 2000 mg in the name is not the amount of magnesium. The page suggests 1–2 tablets a day, which is 230–460 mg of magnesium, so a pack of 90 tablets lasts 45–90 days.