How Long Does Milk of Magnesia Take to Work?
Medically reviewed by Femi Aremu, PharmD
Milk of Magnesia (magnesium hydroxide) is a brand-name medication used to treat occasional constipation in adults and children 6 years and older.
It is an over-the-counter (OTC) saline laxative that starts working within a few hours to relieve constipation.
Milk of Magnesia is available as an oral suspension (liquid). However, other brands of magnesium hydroxide and its active ingredients are also available in other different forms, such as chewable or swallowable tablets.
Milk of magnesia is only indicated for short-term use. It is unsafe to take this drug on a prolonged basis due to the risk of side effects without asking a healthcare provider.
Read on for an in-depth analysis of Milk of Magnesia, including information regarding its dosage requirements, potential side effects, and how quickly you should expect it to begin working.
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Laxatives for Constipation
Laxatives are pharmaceutical products that increase bowel movements and loosen stools. They are often used in the management or treatment of constipation.
Laxatives stimulate intestinal movements and absorb water in the intestine, making stool soft and easy to pass.
Laxatives are usually available in oral tablets, capsules, suspensions, rectal suppositories, and enemas. Laxatives are available on prescription and are also generally available OTC laxatives.
There are different classes of laxatives based on the mode of action. The four main classes of OTC laxatives are:
Bulk-forming laxatives absorb liquid in the intestines, swell, and form a bulky stool, which is easy to pass.
Softeners/lubricants are used short-term and work by softening stools to make them easier to pass.
Stimulant laxatives increase the intestines' activity to cause a bowel movement.
Osmotic laxatives create watery diarrhea so stool can be emptied more easily from the colon.
Some commonly used laxatives include:
What Is Milk of Magnesia?
OTC Milk of Magnesia, containing the active ingredient magnesium hydroxide, treats occasional (irregular) constipation in adults and children 6 years and older.
As a saline laxative, it increases the water content and volume of the stool by retaining the water.
Furthermore, it increases the number of bowel movements, softens the stool, and makes passing easier.
Milk of Magnesia comes as a chewable tablet, swallowable tablet, and a liquid suspension to take by mouth.
Other OTC brand names of magnesium hydroxide are available, such as Pedia-Lax.
Combinational Products
Magnesium hydroxide is also available as combination brands, including Almacone (aluminum hydroxide, magnesium hydroxide, simethicone), a brand-name medication used to treat the symptoms of too much stomach acid, such as stomach upset, heartburn, and acid indigestion.
How Long Does Milk of Magnesia Take to Work?
Milk of Magnesia usually takes 30 minutes to 6 hours to cause a bowel movement after oral administration.
Milk of magnesia is only for short-term or occasional management of constipation.
Dosing Guidelines
Read the dosing guidelines on the label provided carefully before taking the medicine:
Shake well before use.
Do not take more than the recommended daily dose in 24 hours.
Take once daily, preferably at bedtime. You can even divide the doses or as directed by your healthcare provider.
Drink a full glass of water (8 ounces [oz]) with each dose.
Age: | Dose: |
• Adults and adolescents 12 years and older | • 30 milliliters (mL) to 60 mL |
• Children 6-11 years old | • 15mL to 30mL |
• Children 0-5 years old | • Ask a healthcare provider |
Side Effects & Safety
Milk of Magnesia may cause some side effects that usually go away and do not need medical attention.
However, be sure to monitor yourself or a loved one for the emergence of worsening side effects.
Call your healthcare provider if the following symptoms do not go away.
Common Side Effects
Some common side effects of Milk of Magnesia are loose, watery, or more frequent stools.
Severe Side Effects
Other severe side effects include blood in stool or unable to have a bowel movement 6 hours after use.
Who Should Avoid Taking Milk of Magnesia?
Ask your healthcare provider before taking Milk of Magnesia if you have recently experienced any of the following:
A sudden change of bowel habits lasting more than two weeks
Avoid taking any other medication before or after 2 hours of taking Milk of Magnesia to avoid any side effects.
Preventing Constipation
Constipation can be prevented or managed by adopting lifestyle modifications.
Such examples include:
Setting a regular time for defecation
Proper sitting positions
Monitor your bowel habits
Taking a high-fiber diet, vegetables, grains, and fruits.
Regular exercise and physical activity
Plenty of water intake
When non-medical management does not prevent or improve constipation symptoms, then laxatives are an option to manage constipation.
Sometimes, the constipation is caused by other underlying health conditions or a side effect of taking medications. Ask your healthcare provider about ways to manage it.
Summary
OTC laxatives are a first-line treatment option when dietary or lifestyle modifications are ineffective.
Milk of Magnesia is an OTC stimulant laxative used to treat occasional constipation. It softens the stool in the intestine and makes it easy to pass.
The oral suspension starts working within 30 minutes to 6 hours after taking it.
However, use this medicine for a week at maximum. It is a commonly used medicine but may have side effects such as vomiting or blood in stool.
Call your healthcare provider if you have any other medical condition before taking this medicine.
Frequently Asked Questions
How should I store Milk of Magnesia?
Store Milk of Magnesia in a secure location at room temperature (68-77 degrees F) and avoid freezing.
Also, be sure to keep this product away from any areas susceptible to high levels of heat or moisture. Finally, if applicable, keep all medications out of reach of children and pets.
What are probiotics? Can I take them alongside Milk of Magnesia?
Probiotics are beneficial bacteria similar to microorganisms found naturally in the human gut.
You can take magnesium with probiotics.
Read the original article on Verywell Health.
