Antacid / Laxative
Last reviewed June 2026
Who is this for?
Magnesium hydroxide is a gentle antacid and laxative that works by neutralizing excess stomach acid and drawing water into the intestines to help soften stool and make bowel movements easier.
Neutralizes gastric acid by reacting with hydrochloric acid to form magnesium chloride and water, raising intragastric pH and relieving acidic symptoms. Additionally, osmotically draws water into the intestinal lumen, increasing stool bulk and promoting peristalsis to relieve constipation.
Available Over The Counter
Get this from any pharmacy or chemist — no prescription needed.
Explore this drug
For constipation: Take 2 to 4 tablespoons (30–60 mL) of the liquid (like Greens Milk of Magnesia) at bedtime with a full glass of water. For stomach acid or heartburn: Take 1 to 3 teaspoons (5–15 mL) up to 4 times a day, preferably between meals and at bedtime. Shake the bottle well before use.
Magnesium hydroxide is usually taken only when needed, so there is no strict dosing schedule. If you are using it regularly and you miss a dose, take it as soon as you remember. If it is almost time for the next dose, skip the missed one — do not double up.
Do not use magnesium hydroxide as a laxative for more than 7 days without seeing a doctor — long-term use can cause your body to depend on it for bowel movements. Buy only from registered pharmacies, not roadside vendors, to ensure the product is genuine. Drink plenty of water when using it as a laxative to avoid dehydration.
Magnesium hydroxide can reduce the effectiveness of antibiotics like tetracycline and ciprofloxacin — take them at least 2 hours apart. It can also interfere with iron supplements and some blood pressure drugs, so space them out. Alcohol can worsen stomach irritation, so it is best to avoid it.
Check your specific combination
Is it safe to take Magnesium with your other drugs?
Occasional use is generally considered safe during pregnancy and breastfeeding, but consult your doctor or pharmacist before using it regularly.
Store at room temperature in a cool, dry place away from direct sunlight and heat. Keep the bottle tightly closed to prevent contamination. Always keep it out of the reach of children.
For information only — not medical advice. Always talk to a doctor or pharmacist before changing your medication.
Names this drug is sold under — especially in Nigerian and West African pharmacies
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Counterfeit Drug Warning
Fake drugs are a serious problem in Nigeria. Always buy from a registered pharmacy. If the packaging looks different from what is described above, do not use it.