Magnesium hydroxide is a mineral supplement that works as an antacid as well as a laxative. It commonly comes in liquid or tablet form. Dosages vary depending on age, and the directions must be strictly followed to avoid magnesium overdose. Like other supplements or medications, magnesium hydroxide may cause side effects, such as stomach discomfort, vomiting and rectal bleeding, in some people. Certain medications may also interfere with the magnesium hydroxide benefits, such as antibiotics and anti-seizure medications.
This mineral supplement, which is intended only for short-term use, treats problems such as an upset stomach, heartburn, and acid indigestion. Magnesium hydroxide as an antacid is best identified as milk of magnesia. As a laxative, magnesium hydroxide relieves constipation. Overall, the supplement neutralizes stomach acid and increases the water content in the intestines, which helps to soften stool.
As a medication, magnesium hydroxide must be taken by mouth. Liquid forms of the mineral supplement, such as milk of magnesia, must be shaken first, measured with a spoon, and then taken as directed according to the label or a doctor. Other options for magnesium hydroxide include pills or chewable tablets that must also be taken accordingly with a full glass of water. Depending on the person's condition, it may take up to six hours for the mineral to relieve constipation; in general, the medicine should not be taken for longer than one week. As an antacid, milk of magnesia should resolve stomach problems in two weeks or less.
While a magnesium supplement offers the benefits of constipation and acid relief, some people may experience side effects. Some of these include an upset stomach or stomach cramps. Medical attention should be sought immediately if these symptoms occur, plus any other symptoms such as diarrhea, vomiting, loss of appetite, or rectal bleeding. Allergic reactions such as hives or a skin rash may also result as adverse effects from the mineral supplement.
Additionally, a person must take precautions and notify his doctor of other conditions, medications or supplements that may interfere with magnesium, such as vitamin D. Prescriptions that may interact include antibiotics and medications for seizures, fungal infections, and osteoporosis. In addition, a patient with kidney disease or a woman who is pregnant or breast-feeding must consult with a doctor before taking any magnesium-based supplements, antacids or laxatives. To ensure effectiveness, this mineral should be stored at room temperature and away from extreme heat and light.