Indications
- Prevention and treatment of low blood magnesium, which can result from long-lasting diarrhoea, alcohol misuse, poorly controlled diabetes, water tablets (diuretics) or long-term use of acid-reducing medicines such as Omeprazole.
- As part of multivitamin and mineral supplements.
- Doctors sometimes recommend it for muscle cramps or to help prevent migraine.
- In hospital, magnesium sulfate injection is used for eclampsia (fits in pregnancy), severe asthma attacks and some heart rhythm problems.
How It Works
Magnesium is a mineral needed by hundreds of enzymes. It helps muscles and nerves work normally, keeps the heartbeat steady, supports strong bones, and helps the body turn food into energy.
Dosage and Administration
- Adults need about 310 to 420 mg a day, mostly from food such as green vegetables, nuts, pulses and whole grains.
- Supplements (adults): usually 100 to 350 mg of elemental magnesium a day. Higher doses only on a doctor’s advice.
- Treatment of proven deficiency and use in children: as prescribed.
- Injection: given by a doctor or nurse in hospital.
Take with food to reduce stomach upset and diarrhoea. Dividing the daily dose can also help.
Interactions
- Magnesium reduces absorption of Doxycycline and other tetracyclines, Ciprofloxacin and other quinolones, Levothyroxine, bisphosphonates such as Alendronic Acid, and Gabapentin. Take these at least 2 hours apart (4 hours for quinolones).
- Spironolactone and Amiloride can raise magnesium levels.
- Diuretics such as Furosemide and long-term acid-reducing medicines can lower magnesium.
Contraindications
- Severe kidney failure.
- High blood magnesium.
- Injection: heart block and myasthenia gravis, unless the doctor decides otherwise.
- Allergy to any ingredient of the product.
Side Effects
Common: diarrhoea, nausea and stomach cramps, especially at higher doses.
Get urgent medical help for signs of too much magnesium: marked weakness, drowsiness, confusion, flushing, very low blood pressure, slow breathing or a slow or irregular heartbeat. Also get help for a severe allergic reaction.
Pregnancy and Lactation
Magnesium supplements at normal doses are considered safe during pregnancy and breastfeeding. Magnesium sulfate injection is given in hospital when needed for pregnancy complications.
Precautions and Warnings
- Use with care in kidney disease, as magnesium can build up.
- Check the labels of antacids, laxatives and supplements so that you do not take magnesium from several products at once.
- Keep out of the reach of children.
Overdose
Too much magnesium by mouth usually causes diarrhoea. In people with poor kidney function, or with injections, blood magnesium can rise dangerously, causing weakness, drowsiness, slow breathing and heart rhythm problems. Seek medical help straight away.
Therapeutic Class
Mineral supplement; electrolyte replacement.
Storage
Store below 30°C in a dry place, away from light and out of the reach of children.
Prepared by the Oshud Alo team from standard drug references. For information only; always follow your doctor's advice.