User:Mr. Ibrahem/Cetirizine

Cetirizine, sold under the brand name Zyrtec among others, is an antihistamine used to treat hay fever, dermatitis, and urticaria. It is taken by mouth. Effects generally begin within an hour and last for about a day. The degree of benefit is similar to other antihistamines such as diphenhydramine.

Common side effects include sleepiness, dry mouth, headache, and abdominal pain. The degree of sleepiness that occurs with newer histamines is generally less than with first generation antihistamines. Serious side effects may include aggression and angioedema. Use in pregnancy appears safe, but use during breastfeeding is not recommended. It is a second-generation antihistamine and works by blocking histamine H1 receptors, mostly outside the brain.

Cetirizine was patented in 1981 and came into medical use in 1987. It is on the World Health Organization's List of Essential Medicines as an alternative to loratadine. It is available as a generic medication. A month's supply in the United Kingdom costs the NHS just less than £1.20 as of 2021. In the United States the wholesale cost of this amount is about US$2.50. In 2017, it was the 66th most commonly prescribed medication in the United States, with more than eleven million prescriptions.