← Search & browse all drugs

magnesium oxide

A02AA02

Forms & Strengths

Tablet: 400 mg, 424 mg, 500 mg
Capsule: 140 mg (elemental magnesium varies by salt)

Adult Dosing

Magnesium supplementation: 400 to 800 mg daily in divided doses with food
Antacid / Indigestion: 400 mg to 1.2 g as needed
Constipation: 1.5 g to 3 g daily with a full glass of water for short-term use

Pediatric Dosing

Magnesium supplementation: Safety and efficacy not well established; use per pediatrician guidance based on weight/deficiency
Constipation (Children > 6 years): 400 mg to 1.2 g daily with water as short-term laxative

Indications

Treatment and prevention of hypomagnesemia
Short-term relief of occasional constipation
Antacid for treatment of heartburn, acid indigestion, and sour stomach

Mechanism of Action

Acts as a laxative by osmotic action, retaining water in the intestinal lumen and increasing peristalsis
Dissolves in stomach acid to form magnesium chloride, neutralizing gastric hydrochloric acid
Provides elemental magnesium for systemic absorption in the GI tract to correct electrolyte deficiencies

Contraindications

Severe renal impairment (risk of hypermagnesemia and toxicity)
Hypersensitivity to magnesium products
Undiagnosed abdominal pain, intestinal obstruction, or appendicitis
Fecal impaction or colostomy

Adverse Reactions

Diarrhea and watery stools (very common at high doses)
Abdominal cramping and flatulence
Hypermagnesemia (in patients with renal dysfunction, presenting with lethargy, confusion, or hypotension)
Nausea and vomiting

Drug Interactions

Decreases absorption of bisphosphonates, tetracyclines, and fluoroquinolones via chelation (separate by 2 hours)
May decrease absorption of iron, digoxin, and ketoconazole by altering gastric pH or binding
Neuromuscular blocking agents: May enhance or prolong neuromuscular blockade
Potassium-sparing diuretics: Increased risk of hypermagnesemia if renal function is impaired

Curated Content: Needs Vetting Before Put to Clinical Use