From the Guidelines
The recommended dose of milk of magnesia for chronic idiopathic constipation is 500 mg/d to 1 g/d, as this dose is often used in clinical practice, although the studied dose in RCTs was 1.5 g/d 1. When considering the dosing for milk of magnesia, it's essential to weigh the benefits and risks, particularly in patients with renal impairment, as hypermagnesemia can occur with significant renal impairment 1.
- The dose of 500 mg/d to 1 g/d is a common starting point in clinical practice, and it's crucial to monitor patients for adverse effects, such as diarrhea or electrolyte imbalances.
- It's also important to note that magnesium supplements should be avoided in individuals with a creatinine clearance of <20 mg/dL due to the risk of hypermagnesemia 1.
- The combination of efficacy, tolerability, availability of OTC, and low cost make milk of magnesia an attractive first-line option for individuals with chronic idiopathic constipation, but limitations include the small number of clinical trials and lack of long-term effectiveness or harms data 1.
- Patients should be advised to take the medication with a full glass of water and to not use it for more than 7 consecutive days without medical supervision.
- Additionally, patients with kidney disease, heart conditions, or those taking certain medications should consult a healthcare provider before using milk of magnesia due to potential interactions or accumulation of magnesium in the body 1.
From the FDA Drug Label
Active ingredient per 30mL (1 Unit Dose) Magnesium hydroxide 2,400 mg each 30 mL (unit dose) contains Magnesium 1000 mg The dosing for milk of magnesia, which is magnesium hydroxide, is 2,400 mg per 30mL or 1,000 mg of magnesium per 30 mL 2 2.
- The recommended dose is not explicitly stated in the provided drug labels.
- The active ingredient is magnesium hydroxide.
- The unit dose is 30 mL.
From the Research
Dosing for Milk of Magnesia
- The studies provided do not directly address the dosing for milk of magnesia, but rather discuss the effects of various antacids, including aluminum/magnesium hydroxide and magnesium hydroxide, on different conditions such as heartburn and constipation 3, 4, 5, 6.
- In the study by 3, the effects of aluminum/magnesium hydroxide on esophageal and gastric pH in subjects with heartburn were investigated, but the dosing for milk of magnesia was not specifically addressed.
- The study by 6 compared the efficacy of senna and magnesium oxide for the treatment of chronic constipation, and found that magnesium oxide (1.5 g) was effective in improving bowel movements and quality of life, but this does not provide direct information on the dosing for milk of magnesia.
Antacid Interactions
- The studies suggest that antacids, including magnesium hydroxide, can interact with other medications and affect their bioavailability 4, 5.
- For example, the study by 4 found that aluminum-magnesium hydroxide decreased the bioavailability of phenytoin, while the study by 5 found that high-dose calcium carbonate and magnesium hydroxide/aluminum hydroxide reduced the bioavailability of lesinurad.
Magnesium Hydroxide Dosage
- The study by 6 used a dosage of 1.5 g of magnesium oxide for the treatment of chronic constipation, but this does not provide direct information on the dosing for milk of magnesia.
- The study by 5 used high doses of magnesium hydroxide (1600 mg) and aluminum hydroxide (1600 mg) to investigate the effects on lesinurad bioavailability, but this is not directly relevant to the dosing for milk of magnesia.