Pseudoephedrine Hydrochloride is found in over-the-counter cold remedy preparations under various trade names, including Sudafed. It acts as a blood vessel constrictor, thereby relieving congestion. It is commonly used as a symptomatic treatment for rhinitis, including allergic rhinitis.

Unlike antihistamines, which modify systemic allergic responses, pseudoephedrine only minimizes nasal congestion commonly caused by colds or allergies. Pseudoephedrine does not cause drowsiness, an undesired effect of many antihistamines. It is also misused as a stimulant.

Pseudoephedrine is chemically similar to methamphetamine although the biological effects are very different. Because of pseudoephedrine's use as a primary reagent in the manufacture of methamphetamine in illicit labs, USA federal law prohibits buying cold preparations containing pseudoephedrine in quantities greater than 3 packages in any 24-hour period.

Pseudoephedrine Sulfate is the salt form of Pseudoephedrine, used as a time release cold remedy. Found in Drixoral (120mg, lasts 12 hours).