Indications
- As an antacid, to relieve heartburn, acid indigestion and sour stomach. It is often combined with Aluminium Hydroxide, and sometimes with Simethicone for wind.
- As a laxative (often called milk of magnesia), for occasional constipation.
How It Works
Magnesium hydroxide is an alkali that neutralises stomach acid, which eases burning pain. In larger doses it draws water into the bowel, softening the stool and helping the bowel to empty, usually within a few hours.
Dosage and Administration
Strengths differ between products, so follow the label or your doctor’s advice.
- Antacid (adults): commonly 5 to 10 ml of suspension, or 1 to 2 chewable tablets, after meals and at bedtime or when symptoms occur, up to 4 times a day. Shake suspensions well; chew tablets fully.
- Laxative (adults): often 30 to 45 ml of the standard suspension (400 mg in 5 ml) as a single dose at bedtime, with a full glass of water.
- Children: only as advised by a doctor or pharmacist.
Interactions
Magnesium hydroxide reduces the absorption of many medicines, including Doxycycline and other tetracyclines, Ciprofloxacin and other quinolones, iron, Levothyroxine, Digoxin, Ketoconazole, Itraconazole, Gabapentin and bisphosphonates. Take other medicines at least 2 hours before or after it (4 hours for quinolones). It can also make enteric-coated tablets dissolve too early in the stomach.
Contraindications
- Severe kidney disease.
- Blocked bowel, or severe stomach pain of unknown cause, especially with nausea, vomiting or fever (possible appendicitis).
- Allergy to any ingredient of the product.
Side Effects
Diarrhoea and stomach cramps are the most common. In people with kidney problems, magnesium can build up in the blood and cause weakness, drowsiness, low blood pressure and a slow heartbeat.
Get urgent medical help for severe stomach pain, black or bloody stools, vomiting blood, marked muscle weakness with drowsiness or slow breathing, or a severe allergic reaction.
Pregnancy and Lactation
Occasional use as an antacid is generally considered acceptable in pregnancy and while breastfeeding. Ask your doctor before regular or laxative use.
Precautions and Warnings
- Use with care in kidney disease and in older people.
- Do not use as a laxative for more than a week without medical advice.
- See a doctor if heartburn lasts more than 2 weeks, or if you have weight loss, difficulty swallowing, vomiting or black stools.
- Drink enough fluids when using it as a laxative.
Overdose
Too much can cause severe diarrhoea and dehydration. In people with poor kidney function it can raise blood magnesium to dangerous levels, causing weakness, confusion and a slow heartbeat. Seek medical help.
Therapeutic Class
Antacid; osmotic laxative.
Storage
Store below 30°C in a dry place, away from light and out of the reach of children. Do not freeze suspensions, and keep the cap tightly closed.
Prepared by the Oshud Alo team from standard drug references. For information only; always follow your doctor's advice.