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Nasex Side Effects

Generic name: guaifenesin / phenylephrine

Medically reviewed by Last updated on Feb 11, 2024.

Note: This document contains side effect information about guaifenesin / phenylephrine. Some dosage forms listed on this page may not apply to the brand name Nasex.

Applies to guaifenesin / phenylephrine: oral liquid, oral syrup, oral tablet.

Serious side effects of Nasex

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:

Other side effects of Nasex

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 guaifenesin/phenylephrine: oral capsule, oral capsule extended release, oral drops, oral liquid, oral suspension, oral syrup, oral tablet, oral tablet extended release.


The manufacturer has not provided adverse event information.[Ref]


1. (2019) "Product Information. Gilphex TR (guaifenesin-phenylephrine)." Gil Pharmaceutical Corporation

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.