Phenylephrine is a selective α1-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.