GDP-EX Side Effects

Generic name: dextromethorphan / guaifenesin / phenylephrine

Medically reviewed by Drugs.com. Last updated on Jan 15, 2024.

Note: This document provides detailed information about GDP-EX Side Effects associated with dextromethorphan / guaifenesin / phenylephrine. Some dosage forms listed on this page may not apply specifically to the brand name GDP-EX.

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

Important warnings This medicine can cause some serious health issues

Do not use this medicine if you are using or if you have used an MAO inhibitor in the past 14 days.

A dangerous drug interaction could occur.

MAO inhibitors include isocarboxazid, linezolid, methylene blue injection, phenelzine, and tranylcypromine.

Get emergency medical help if you have signs of an allergic reaction: hives, difficult breathing, swelling of your face, lips, tongue, or throat.

Stop using this medicine and call your doctor at once if you have:

• little or no urination;

• fast or slow heartbeats;

• confusion, dizziness, feeling unsteady;

• nervousness, sleep problems (insomnia);

• severe nausea or vomiting;

• severe headache, blurred vision, pounding in your neck or ears;

• slow breathing; or

• unusual changes in mood or behavior.

Common side effects may include:

• diarrhea, constipation;

• dizziness, drowsiness;

• sleep problems (insomnia); or

• feeling nervous, restless, or irritable.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects.

For healthcare professionals

Applies to dextromethorphan/guaifenesin/phenylephrine: oral capsule, oral liquid, oral suspension, oral suspension extended release, oral syrup, oral tablet, oral tablet extended release.

General adverse events

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

Further information

GDP-EX side effects can vary depending on the individual. 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.

Medical Disclaimer