What it is used for
- Treating and preventing low magnesium levels
- Supporting muscle and nerve function
- Some forms used to relieve constipation or indigestion
- Used in certain conditions on clinician advice, such as during pregnancy when indicated
How it works
Magnesium is a mineral involved in hundreds of body processes, including muscle and nerve function, blood pressure regulation, blood sugar control and bone health. Supplementing restores levels when intake or absorption is low, helping these systems work normally.
How it is taken
Available as tablets, capsules, powders and liquids in several salt forms, some of which also act as laxatives or antacids. It is usually taken with water, often with food to reduce stomach upset. Take it exactly as your doctor, pharmacist or the label directs.
No doses here on purpose. The right strength and schedule depend on you — only a doctor or pharmacist should set them. Always follow your prescription and the label.
Common side effects
- Diarrhoea or loose stools
- Stomach cramps
- Nausea
Serious effects — get help
- Signs of very high magnesium, especially with kidney problems: muscle weakness, very low blood pressure, slow or irregular heartbeat, drowsiness or breathing difficulty
- Severe allergic reaction (rare)
If a reaction is severe — for example trouble breathing, swelling of the face or throat, or collapse — go to the nearest emergency room now or call your local emergency number. Do not wait for an online consultation.
Interactions to watch
- Some antibiotics (tetracyclines, quinolones) and bisphosphonates, which should be spaced apart
- Certain water pills and heart medicines
- Other antacids or laxatives that also contain magnesium
Who should take care
- Tell your clinician if you have kidney disease, as magnesium can build up to dangerous levels
- Start low if using for constipation to avoid excessive diarrhoea
- Space it away from certain antibiotics and other minerals as advised
- Discuss use in pregnancy and breastfeeding with your clinician