Toxicity of Over-the-Counter Stimulants

Over-the-counter stimulants (phenylpropanolamine hydrochloride, ephedrine, pseudoephedrine, caffeine) are used widely as decongestants, anorectic agents, amphetamine substitutes, and “legal stimulants.” Toxic effects may result from overdose, drug interactions, or diseases that increase sensitivity to sympathomimetic agents. The most important toxic effect of the a-adrenergic agonist phenylpropanolamine is hypertension, which may result in hypertensive encephalopathy or intracerebral hemorrhage. The therapeutic index of phenylpropanolamine is low, and severe hypertension may occur after ingestion of less than three times the therapeutic dose. Ephedrine and pseudoephedrine may also cause hypertension, as well as tachyarrhythmias due to β-adrenergic stimulation. Toxic reactions from caffeine are characterized by agitation, seizures, tachyarrhythmias, and hypotension. Management of toxic reactions to over-the-counter stimulants includes control of hypertension with a rapidly acting vasodilator, β-blockers for tachyarrhythmias, and control of seizures.