High Quality Content by WIKIPEDIA articles! Pseudoephedrine (PSE) is a sympathomimetic drug of the phenethylamine and amphetamine chemical classes used as a nasal/sinus decongestant and stimulant or wakefulness-promoting agent. The salts pseudoephedrine hydrochloride and pseudoephedrine sulfate are found in many over-the-counter preparations either as single-ingredient preparations, or more commonly in combination with antihistamines, guaifenesin, dextromethorphan, paracetamol (acetaminophen), and/or NSAIDs (e.g., aspirin, ibuprofen, etc).