What is "phenylephrine"

n. (context pharmaceutical drug English) An α-adrenergic receptor agonist; 3-(1-hydroxy-2-methylamino-ethyl)phenol, with the formula C₉H₁₃NO₂.

n. a powerful vasoconstrictor used to dilate the pupils and relieve nasal congestion

Phenylephrine is a selective α-adrenergic receptor agonist of the phenethylamine class used primarily as a decongestant, as an agent to dilate the pupil, and to increase blood pressure. Phenylephrine is marketed as an alternative for the decongestant pseudoephedrine, although clinical trials show phenylephrine, taken orally at the recommended dose, to be no more effective than placebo. Phenylephrine can also cause a decrease in heart rate through reflex bradycardia.