milk of magnesia

Milk of magnesia, also known by the generic name magnesium hydroxide, is a medicine that is used as a hydrating laxative and an antacid. It is not a dairy product, but rather a milky-white liquid that is made from magnesium hydroxide, purified water, and sodium hypochlorite. This medicine usually relieves uncomfortable gastrointestinal symptoms within 30 minutes and constipation within six hours.

Treatment of Stomach Discomfort

Magnesium hydroxide is an alkaline suspension, which means that it is able to neutralize acids. When a patient swallows this medicine, the hydroxide ions in it react with the hydrogen ions in stomach acid, transforming both into water. This makes milk of magnesia effective in fighting excess stomach acid, which can cause indigestion, heartburn, and stomach ulcers. When used as an antacid, the usual adult dose is from 0.02 – 0.05 oz (500 mg to 1,500 mg).

Treatment of Constipation

The magnesium in milk of magnesia is what makes it an effective laxative. The mineral ions draw water into the intestinal tract from the surrounding body tissues. This extra water softens and increases the volume of feces, which stimulates the nerves in the intestines and causes a bowel movement. For the treatment of constipation, an adult dose is between 0.07 – 0.18 oz (2,000 mg and 5,000 mg).