Flanax Antacid Liquid Side Effects
Generic name: aluminum hydroxide / magnesium hydroxide / simethicone
Medically reviewed by Drugs.com. Last updated on Jul 29, 2022.
Note: This document contains side effect information about aluminum hydroxide / magnesium hydroxide / simethicone. Some dosage forms listed on this page may not apply to the brand name Flanax Antacid Liquid.
Applies to aluminum hydroxide / magnesium hydroxide / simethicone: oral liquid, oral suspension, oral tablet chewable.
Serious side effects
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.
Other side effects
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 https://www.fda.gov/medwatch.
For Healthcare Professionals
Uncommon (0.1% to 1%): Constipation, diarrhea
Very rare (less than 0.01%): Hypermagnesemia
Frequency not reported: Hyperaluminemia, hyperphosphatemia[Ref]
Frequency not reported: Increased bone resorption, osteomalacia[Ref]
Frequency not reported: Hypercalciuria[Ref]
More about Flanax Antacid Liquid (aluminum hydroxide / magnesium hydroxide / simethicone)
Related treatment guides
1. "Product Information. Amphojel (aluminum hydroxide)." Wyeth-Ayerst Laboratories (2001):
2. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0
3. Cerner Multum, Inc. "Australian Product Information." O 0
4. "Product Information. Antacid Regular Strength (Al hydroxide/Mg hydroxide/simethicone)." Geri-Care Pharmaceuticals (2022):
5. "Product Information. Mylanta Maximum Strength Vanilla Caramel (Al hydroxide/Mg hydroxide/simethicone)." Infirst Healthcare Inc (2022):
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.