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Nasex-G Side Effects

Generic Name: guaifenesin / phenylephrine

Note: This page contains side effects data for the generic drug guaifenesin / phenylephrine. It is possible that some of the dosage forms included below may not apply to the brand name Nasex-G.

For the Consumer

Applies to guaifenesin / phenylephrine: controlled-release tablets, liquid, solution, suspension, sustained-release capsules, sustained-release tablets (12 hour), syrup, tablets

Check with your doctor if any of these most COMMON side effects persist or become bothersome:

Dizziness; excitability; headache; nausea; nervousness or anxiety; trouble sleeping; weakness.

Seek medical attention right away if any of these SEVERE side effects occur while taking guaifenesin / phenylephrine:

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); difficulty urinating; fast or irregular heartbeat; hallucinations; seizures; severe dizziness, lightheadedness, or headache; tremor.

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


Cardiovascular side effects have included tachycardia, palpitations, arrhythmias, and cardiovascular collapse with hypotension.[Ref]

Nervous system

Nervous system side effects have included central nervous system depression, tremor, headache, dizziness, restlessness, insomnia, and convulsions.[Ref]


Psychiatric side effects have included fear, nervousness, anxiety, and hallucinations.[Ref]


Gastrointestinal side effects have included nausea and vomiting.[Ref]


Respiratory side effects have included breathing difficulty.[Ref]


Genitourinary side effects have included dysuria.[Ref]


Dermatologic side effects have included pallor.[Ref]


General side effects have included weakness.[Ref]


1. "Product Information. Duratuss GP (guaifenesin-phenylephrine)." Victory Pharma, San Diego, CA.

2. "Product Information. Duratuss (guaifenesin-phenylephrine)." Victory Pharma, San Diego, CA.

It is possible that some side effects of Nasex-G may not have been reported. These can be reported to the FDA here. Always consult a healthcare professional for medical advice.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.