Milk of Magnesia, often referred to as MoM, is an over-the-counter preparation used for common digestive issues. The active ingredient is magnesium hydroxide, which provides two distinct actions. It functions as both a saline laxative and an antacid, addressing occasional constipation and temporary heartburn or indigestion. Understanding the correct frequency for each use is necessary for effectiveness and safety.
Recommended Frequency for Constipation Relief
Milk of Magnesia is primarily known for its use as a laxative, working as an osmotic agent. Magnesium hydroxide draws water from surrounding tissues into the intestines, softening the stool and promoting bowel movements. Relief from irregularity typically occurs within 30 minutes to six hours after dosing.
The standard adult dose for constipation relief (individuals 12 years and older) is usually between 30 mL and 60 mL of the liquid suspension. This dose should generally be taken only once daily, as a single administration is often sufficient. Many individuals find it effective to take the dose at bedtime, allowing the medication to work overnight.
It is important to drink a full 8-ounce glass of water with each dose. Because the drug works by pulling water into the colon, maintaining adequate hydration is essential for the medication to function properly and prevent dehydration. If a bowel movement is not achieved after the initial dose, a second dose should only be considered after consulting product labeling or a healthcare professional.
The maximum daily dose should not exceed 60 mL in a 24-hour period. Exceeding this limit increases the risk of side effects, as the goal is to restore normal bowel function, not induce excessive diarrhea.
Recommended Frequency for Heartburn Relief
When used as an antacid, Milk of Magnesia neutralizes excess stomach acid, providing quick relief from symptoms like heartburn and acid indigestion. This use requires a much smaller dose compared to the amount needed for laxative purposes. The antacid effect begins almost immediately, unlike the delayed onset of its laxative action.
The recommended adult dosage for antacid use ranges from 5 mL to 15 mL of the liquid suspension. This dose can be taken as needed for symptom relief, but the frequency is strictly limited. A dose can generally be repeated up to four times per day.
The total amount of Milk of Magnesia taken in a single day for antacid purposes should not exceed 60 mL. It is important to space out these administrations to allow the antacid to work without excessive accumulation of magnesium. This use is intended only for the temporary relief of stomach discomfort, such as after a meal.
Important Safety Warnings and Duration of Use
MoM should only be used for a short duration, regardless of whether it is used as a laxative or an antacid. The medication is not intended for chronic use and should never be taken for extended periods without medical guidance. This is due to the potential for laxative dependence and serious electrolyte imbalances.
For constipation relief, MoM should not be used for more than seven consecutive days. When used as an antacid, the medication should not be taken at the maximum dose for more than 14 consecutive days. Continuing to rely on MoM beyond these durations suggests an underlying medical issue that requires professional evaluation.
One risk of extended overuse is hypermagnesemia, an excessive amount of magnesium in the blood. Individuals with kidney impairment are at a significantly higher risk because their kidneys cannot effectively excrete the absorbed magnesium. Symptoms of high magnesium levels include muscle weakness, slow heart rate, and confusion.
Common side effects, such as diarrhea and abdominal cramping, indicate the medication is working, but excessive diarrhea can lead to dehydration. Patients should stop taking the drug and consult a doctor if they experience severe abdominal pain, rectal bleeding, or no bowel movement after the laxative dose. MoM can also interact with certain prescription drugs, including some antibiotics, by reducing their absorption.