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Phillips' Milk of Magnesia Side Effects

Generic name: magnesium hydroxide

Medically reviewed by Last updated on Dec 25, 2020.

Note: This document contains side effect information about magnesium hydroxide. Some of the dosage forms listed on this page may not apply to the brand name Phillips' Milk of Magnesia.

For the Consumer

Applies to magnesium hydroxide: oral suspension, oral tablet chewable

What are some side effects that I need to call my doctor about right away?

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

  • Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.

What are some other side effects of this drug?

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.

You may report side effects to the FDA at 1-800-332-1088. You may also report side effects at

For Healthcare Professionals

Applies to magnesium hydroxide: compounding powder, oral concentrate, oral suspension, oral tablet chewable


The most commonly reported side effects included hypermagnesemia, abdominal pain, diarrhea, and colic.[Ref]


Patients with renal dysfunction may be at higher risk of magnesium accumulation, which could result in toxic effects.[Ref]

Very rare (less than 0.01%): Hypermagnesemia[Ref]


Diarrhea was a dose-dependent side effect.[Ref]

Frequency not reported: Abdominal pain, colic, diarrhea[Ref]


1. "Product Information. Milk of Magnesia (magnesium hydroxide)." Major Pharmaceuticals Inc, Livonia, MI.

2. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0

3. "Product Information. Pedia-Lax Chewable (magnesium hydroxide)." Fleet, CB, Lynchburg, VA.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.