Mineral supplements. Macrominerals
ATC code: A12CC-MAGNESIUM (Magnesium (oral salts, generic group))
Brand names – drugs
Magnerot
Brand names – supplements
Natural Vitality Calm, Doctor's Best High Absorption Magnesium, NOW Foods Magnesium Citrate
Supplements are not tested in clinical trials and are not registered as medications.
Magnesium is a cofactor for more than 300 enzyme systems, including ATP synthesis, transmembrane calcium and potassium transport, and nucleic acid synthesis. It stabilises myocardial and neuronal membrane electrical activity. Reduces acetylcholine release at neuromuscular junctions, explaining the effect in eclampsia. Salts differ in bioavailability: citrate and glycinate are highly bioavailable (35–40%), oxide is low (4–5%), and sulphate has an osmotic laxative effect.
First line
Oral magnesium salts (citrate, lactate, glycinate) are first-line for documented hypomagnesaemia without severe clinical features. When serum magnesium falls below 0.5 mmol/L or patients have arrhythmias or seizures, intravenous magnesium sulphate is used. The underlying cause is identified and addressed in parallel: diuretics, proton pump inhibitors, chronic diarrhoea, alcoholism.
First line
Intravenous magnesium sulphate is the standard for seizure prophylaxis and treatment in severe pre-eclampsia and eclampsia. The multicentre Magpie trial (Lancet 2002, more than 10,000 women) showed a 58% reduction in eclampsia risk. ACOG 2020 and Russian Ministry of Health guidelines include magnesium sulphate as a required component of severe pre-eclampsia management. Oral forms are not used in this indication.
This indication applies to parenteral magnesium sulphate, not over-the-counter oral magnesium. It is administered intravenously or intramuscularly in hospital.
Sources
Adjunct
Magnesium citrate or oxide 400–600 mg daily is considered for migraine prophylaxis in patients with contraindications to beta-blockers and topiramate and in women planning pregnancy. Cochrane 2022 rated the effect as modest but clinically meaningful: 20–40% reduction in attack frequency versus placebo. AAN 2012 classifies magnesium as level B (probably effective). The effect develops after 4–8 weeks.
Does not replace standard prophylaxis in frequent or severe migraine. Considered for episodic migraine without aura.
Not recommended
The 2020 Cochrane review (11 RCTs, 735 participants) did not confirm the effect of magnesium in idiopathic nocturnal leg cramps in non-pregnant adults. In pregnant women, the effect is weak and clinically insignificant. International guidelines (AAN, BMJ Best Practice) do not include magnesium in first-line therapy. Patients with confirmed hypomagnesaemia are a different indication.
In confirmed hypomagnesaemia, use is justified – but this is a different scenario from typical nocturnal cramps.
Not recommended
High-quality RCTs are absent. Small studies showed a weak effect on subjective stress in healthy adults, not exceeding placebo under controlled conditions. International psychiatry societies (APA, NICE mental health) do not include magnesium in anxiety treatment guidelines. Clinically significant anxiety or depression requires specialist consultation.
Oral magnesium at physiological doses is safe in pregnancy. Intravenous magnesium sulphate is used in severe pre-eclampsia and in preterm birth for foetal neuroprotection at 24–32 weeks gestation.
Transfers into breast milk in small amounts. Use at physiological doses in breastfeeding does not require cessation of breastfeeding.