Mydex Side Effects
Generic name: guaifenesin / phenylephrine
Medically reviewed by Drugs.com. Last updated on Aug 21, 2022.
Note: This document contains side effect information about guaifenesin / phenylephrine. Some dosage forms listed on this page may not apply to the brand name Mydex.
Applies to guaifenesin / phenylephrine: oral liquid, oral syrup, oral tablet.
Serious side effects of Mydex
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 of Mydex
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:
- Feeling nervous and excitable.
- Not able to sleep.
- Feeling sleepy.
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
The manufacturer has not provided adverse event information.[Ref]
More about Mydex (guaifenesin / phenylephrine)
Related treatment guides
1. "Product Information. Gilphex TR (guaifenesin-phenylephrine)." Gil Pharmaceutical Corporation (2019):
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.