Pseudoephedrine

Pseudoephedrine (commonly abbreviated as PSE) is a decongestant. The salts pseudoephedrine hydrochloride and pseudoephedrine sulfate are found in many over-the-counter drugs either as single-ingredient preparations, or more commonly in combination with antihistamines, paracetamol (acetaminophen) and/or ibuprofen. Sudafed is a trademark for a common brand which contains pseudoephedrine hydrochloride, though Sudafed PE does not. Drugs containing pseudoephedrine are commonly used as a treatment for Rhinitis (an inflammation of the mucous mebranes in the nose)
Unlike antihistamines, which modify the systemic histamine-mediated allergic response, pseudoephedrine only relieves nasal congestion commonly associated with colds or allergies.
The advantage of oral pseudoephedrine over topical nasal preparations, such as oxymetazoline, is that it does not cause rebound congestion (rhinitis medicamentosa); however, it is more likely to cause adverse effects, including high blood pressure.
Some countries started to replace pseudoephedrine by other drugs, such as phenylephrine. The reason for this is that pseudoephedrine can be used to make methamphetamine, which is an illegal drug.