From the Guidelines
Milk of Magnesia (Magnesium Hydroxide) is an osmotic laxative used to treat constipation.
Key Characteristics
- It works by creating an osmotic gradient in the GI tract, leading to net secretion of water and electrolytes, which helps to relieve constipation-related symptoms 1
- The typical dose used in clinical practice is 500 mg/d to 1 g/d, although higher doses of 1.5 g/d have been used in trials 1
- It is available over-the-counter (OTC) and is considered a low-cost option for treating constipation 1
- However, its use should be avoided in patients with significant renal impairment due to the risk of hypermagnesemia 1
Clinical Use
- Milk of Magnesia is suggested as a first-line option for individuals with chronic idiopathic constipation (CIC) due to its efficacy, tolerability, and low cost 1
- It can be used in combination with other agents, such as fiber supplements or stimulant laxatives, to manage constipation symptoms 1
- The American Gastroenterological Association recommends starting with a lower dose and increasing as needed, while also avoiding use in patients with renal insufficiency 1
From the FDA Drug Label
PRINCIPAL DISPLAY PANEL - 30 mL Cup Tray Label NDC 0121-0431-30 Milk of Magnesia USP ANTACID, SALINE LAXATIVE Active ingredient (in each 5 mL) Magnesium hydroxide 400 mg Other information each teaspoonful (5 mL) contains:magnesium 400 mg Milk of Magnesia (Magnesium Hydroxide) is an antacid and saline laxative that contains Magnesium Hydroxide as its active ingredient 2, 2, 2.
- It is used to neutralize stomach acid and stimulate bowel movements.
- The typical dosage contains 400 mg of Magnesium Hydroxide per 5 mL.
From the Research
Definition and Composition
- Milk of magnesia, also known as magnesium hydroxide, is a compound used as a laxative to treat constipation and fecal incontinence 3, 4.
- It is composed of magnesium hydroxide, which can help stimulate bowel movements and soften stool.
Medical Uses
- Milk of magnesia is used to treat constipation, fecal incontinence, and abdominal pain in children and adults 3, 4.
- It is also used as an antacid to neutralize stomach acid and relieve heartburn and indigestion.
- In some cases, milk of magnesia is used to prevent postoperative ileus after major surgical procedures, such as gynecologic operations 5.
Side Effects and Interactions
- Excessive ingestion of milk of magnesia can lead to hypermagnesemia, a condition characterized by elevated magnesium levels in the blood 6, 7.
- Hypomagnesemia, or low magnesium levels, can also occur due to excessive diarrhea caused by milk of magnesia 6.
- Milk of magnesia can interact with other medications, such as lithium, and decrease their absorption 7.
Efficacy and Safety
- Studies have shown that milk of magnesia is effective in treating constipation and fecal incontinence in children and adults 3, 4.
- However, its efficacy and safety may vary depending on the individual and the dosage used 4.
- Milk of magnesia is generally considered safe when used as directed, but it can cause adverse effects, such as diarrhea, abdominal pain, and nausea, in some individuals 3, 4.