Milk of Magnesia: An OTC Option for Constipation

Medically reviewed by Jay N. Yepuri, MD

Milk of Magnesia, also known as magnesium hydroxide, is a common over-the-counter remedy used as both a laxative for treating constipation and an antacid for heartburn.

While generally safe for adults and children within recommended doses, Milk of Magnesia's use in children requires additional consideration as it may not be well-tolerated in some children.

This article will explain how Milk of Magnesia works, its uses, standard dosage, and side effects to keep in mind.

Milk of Magnesia for Constipation: How Does It Work?

Magnesium hydroxide, the active ingredient in Milk of Magnesia, is in a class of medications called saline laxatives. It is an osmotic laxative, meaning that when ingested, it draws water into the intestines, softening stool consistency and stimulating bowel movements.

The increased water content in the colon facilitates a smoother passage of stool and aids in alleviating constipation discomfort. Its osmotic effect within the intestines helps promote regularity and eases bowel movements, providing relief from constipation.

Other Uses of Milk of Magnesia

Magnesium hydroxide is sometimes used as an antacid along with other medications to treat heartburn, upset stomach, and indigestion. It works by neutralizing excess stomach acid, providing relief from the burning sensation and discomfort associated with heartburn.

Magnesium hydroxide is often combined with calcium carbonate or aluminum hydroxide in commercial products for a more comprehensive effect or to balance out its potential side effects, like its laxative properties.

Standard Milk of Magnesia Dosage

As a laxative for occasional constipation, the recommended maximum daily dose of Milk of Magnesia is 60 milliliters (mL) within 24 hours. It can be taken with a glass of water, and it is important to shake well before use. These dosages may be taken once a day, in divided doses, or as directed by your healthcare provider.

Dosage guidelines for constipation:

• For adults and children aged 12 and older, the recommended quantity ranges between 30 mL (2 tablespoons) to 60 mL (4 tablespoons).

• For children aged 6 to 11, the suggested dose varies from 15 mL (1 tablespoon) to 30 mL (2 tablespoons).

• For children under 6, consulting with a healthcare provider is recommended.

When magnesium hydroxide is used as an antacid, it is important to adhere to the maximum recommended daily dosage within a 24-hour period. Ensure proper shaking of the product before consumption and consider diluting it with water if preferred.

Dosage guidelines for use as an antacid:

• For adults and children aged 12 years and above, the suggested dosage ranges from 5 to 15 mL (equivalent to 1 to 3 teaspoonfuls).

• For children under 12 years old, talk to a healthcare professional before using.
  

Possible Side Effects

Magnesium hydroxide might lead to certain side effects. Inform your healthcare provider if you experience persistent or bothersome symptoms, such as:

• Loose or watery stools

• Increased bowel movements

Additionally, some severe side effects require immediate attention. If you notice blood in your stool or are unable to have a bowel movement for six hours after using magnesium hydroxide, discontinue its use and contact your healthcare provider promptly.

Should Anyone Avoid Milk of Magnesia?

Magnesium hydroxide may be contraindicated for some people. Before consuming Milk of Magnesia, consult your healthcare provider if you:

• Have kidney disease

• Adhere to a magnesium-restricted diet

• Experience nausea, vomiting, or stomach pain

Seek medical advice if you notice a sudden change in bowel habits lasting more than 14 days. Additionally, if you're taking prescription medication, consult a healthcare provider or pharmacist before use, as this product may interact with certain prescriptions.

Discontinue use and consult a healthcare provider if you experience rectal bleeding or fail to have a bowel movement after using this product, as these could indicate a serious condition.

Milk of Magnesia Not Working: Other Ways to Relieve Constipation

Occasionally, Milk of Magnesia might not provide the expected relief from constipation. If this happens, talk to your healthcare provider about alternative options that may work for you.

Other ways to relieve constipation include:

• Eat more fruits, vegetables, and grains abundant in fiber.

• Ensure adequate hydration by drinking plenty of water and other fluids.

• Get enough exercise to support healthy bowel movements.

• Take the necessary time when you feel the urge for a bowel movement.

• Use laxatives only under the advice of your healthcare provider.

• Consult your healthcare provider regarding any medications that might contribute to constipation as a potential side effect.

Talk to your healthcare provider about alternative over-the-counter laxatives or stool softeners, such as:

• Other osmotic laxatives

• Bulk-forming laxatives

• Lubricant laxatives

• Stool softeners

• Stimulant laxatives

Consult with a healthcare provider before trying new remedies for personalized guidance and to ensure safe and effective solutions for constipation relief.

When to See a Healthcare Provider

If you're experiencing any of the following, it's crucial to reach out to your healthcare provider for further guidance:

• Not having had a bowel movement in three days

• Experiencing bloating or stomach pain

• Dealing with nausea or vomiting

• Noticing blood in your stool

Seeking guidance from your provider can provide reassurance and appropriate care. Don't hesitate to reach out if you're encountering these symptoms.

Summary

The mechanism of Milk of Magnesia involves its osmotic effect, drawing water into the intestines to soften stool consistency and facilitate bowel movements. It is also used as an antacid—often along with other agents—to neutralize excessive stomach acid to ease the discomfort of heartburn and indigestion.

Fortunately, Milk of Magnesia is generally considered safe when used in recommended dosages. Talk with your healthcare provider if you experience side effects, the medication is not working, or you are interested in alternative medication options.

Read the original article on Verywell Health.