Zyrtec-D is an over-the-counter drug used to treat several allergy symptoms, including nasal congestion, sneezing, and runny nose. The drug contains an antihistamine and a decongestant. Zyrtec-D comes in tablet form and is taken twice a day, with about 12 hours in between doses. Common side effects include insomnia, dry mouth, and fatigue.
Zyrtec-D contains cetirizine (an antihistamine) and pseudoephedrine (a decongestant). Although the drug was originally a prescription product, it is now available without a prescription. However, because Zyrtec-D contains pseudoephedrine, it is kept "behind the counter" at pharmacies, due to laws that regulate the sale of pseudoephedrine. These laws were put in place to prevent the use of pseudoephedrine for making methamphetamine ("crystal meth"). You do not need a prescription, but you will need to show ID and sign for the medication.