guaifenesin and phenylephrine

What is guaifenesin, phenylephrine, and how does it work (mechanism of action)?

Guaifenesin/phenylephrine is a medication that contains two different drugs, an expectorant (guaifenesin) and a decongestant (phenylephrine). The expectorant effects of guaifenesin promote drainage of mucus from the lungs by thinning the mucus. It also lubricates the irritated respiratory tract. Phenylephrine relieves stuffy nose by constricting blood vessels in the nasal air passages. This reduces the flow of fluid out of the blood vessels and into the tissues of the air passages.

What brand names are available for guaifenesin, phenylephrine?

Sudafed PE Non-Drying Sinus Caplets, (Entex, discontinued)

Is guaifenesin, phenylephrine available as a generic drug?


Do I need a prescription for guaifenesin, phenylephrine?


What are the side effects of guaifenesin, phenylephrine?

Side effects of guaifenesin/phenylephrine and include stimulation of the nervous system leading to nervousness, restlessness, excitability, dizziness, headache, fear, anxiety, tremor, and even hallucinations and convulsions (seizures). Nausea, vomiting, and rash also occur.

What is the dosage for guaifenesin, phenylephrine?

Guaifenesin/phenylephrine may be taken with or without food. It must be used cautiously in patients with heart (coronary artery) disease and angina, and diabetes.

Which drugs or supplements interact with guaifenesin, phenylephrine?

Guaifenesin/phenylephrine should not be taken with MAO inhibitors drugs due to the increased risk of serious adverse effects


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Is guaifenesin, phenylephrine safe to take if I'm pregnant or breastfeeding?

Phenylephrine can cause birth defects in some animal species. Additionally, there have been associations between first trimester exposure to these medications and malformations, primarily minor malformations. Although one analysis found a correlation between guaifenesin use in the first trimester of pregnancy and an increased risk of hernia, others found no increased risk of malformations. Thus, guaifenesin/phenylephrine should be used in pregnancy only if the physician feels that the potential benefits outweigh the potential risks.

Small amounts of phenylephrine is excreted in breast milk.

What else should I know about guaifenesin, phenylephrine?

What preparations of guaifenesin, phenylephrine are available?

Caplet: 5 mg/200 mg

How should I keep guaifenesin, phenylephrine stored?

Store at room temperature below 30 C (86 F).


Guaifenesin and phenylephrine (Sudafed PE Non-Drying Sinus Caplets, (Entex, discontinued) is a drug is prescribed for the relief of sneezing, nasal congestion from the common cold, runny nose, sinusitis, sore throat, or bronchitis. Side effects, drug interactions, dosage, and pregnancy safety information should be reviewed prior to taking this medication.

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Medically reviewed by John Cunha, DO

Reference: FDA Prescribing Information