Zyrtec is a brand name for cetirizine, an antihistamine that belongs to the second-generation class of antihistamines. Antihistamines are drugs that block the effects of histamine, a chemical that is released by the immune system in response to allergens, such as pollen, dust, animal dander, or insect bites. Histamine causes symptoms such as sneezing, itching, watery eyes, and runny nose, which are common in allergic rhinitis (hay fever) and urticaria (hives). Zyrtec is used to treat these symptoms and provide relief for 24 hours.


Cetirizine was first synthesized in 1981 by a team of researchers at the pharmaceutical company UCB, led by Jean-Charles Schwartz. It was derived from hydroxyzine, an older antihistamine that also has sedative and anti-anxiety effects. Cetirizine was designed to have a higher selectivity for the H1 histamine receptor, which is responsible for allergic reactions, and a lower affinity for the H2 histamine receptor, which is involved in gastric acid secretion. Cetirizine was also expected to have less penetration into the central nervous system, and therefore less sedation, than hydroxyzine3 .

Cetirizine was first marketed in Europe in 1987 under the brand name Zirtec. It was later introduced in the United States in 1995 under the brand name Zyrtec. Zyrtec was initially available only by prescription, but it became over-the-counter (OTC) in 2007. Zyrtec is now one of the most popular antihistamines in the world, with sales exceeding $1 billion in 2019 .

How to Use

Zyrtec is available in different forms, such as tablets, liquid gels, syrup, and chewables. The recommended dose for adults and children 6 years and over is one 10 mg tablet once daily. A 5 mg tablet may be appropriate for less severe symptoms. Zyrtec can be taken with or without food, and should be swallowed whole. Zyrtec should not be taken more than once in 24 hours, unless directed by a doctor.

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Zyrtec should be used only as directed, and not for longer than needed. Zyrtec may interact with other medicines that cause drowsiness, such as alcohol, sedatives, tranquilizers, painkillers, muscle relaxers, and antidepressants. Zyrtec may also affect the results of some allergy tests, so it should be stopped at least 3 days before undergoing such tests. Zyrtec should be used with caution in people with liver or kidney problems, as they may need a lower dose or a different dosing schedule. Zyrtec should not be used in people who are allergic to cetirizine or similar drugs, such as levocetirizine or hydroxyzine.

Zyrtec should be stored at room temperature, away from moisture, heat, and light. Zyrtec should be kept out of reach of children and pets. Zyrtec should not be used if the blister pack is torn or broken. Zyrtec should be discarded when it is expired or no longer needed.

Cons and Pros

Zyrtec, like any other medicine, has its cons and pros. Some of the possible cons and pros of Zyrtec are:


  • Zyrtec may cause side effects, such as drowsiness, dry mouth, headache, dizziness, nausea, or stomach pain. These side effects are usually mild and temporary, but they may affect some people more than others. Zyrtec may also cause rare but serious side effects, such as allergic reactions, liver problems, or seizures. These side effects require immediate medical attention.
  • Zyrtec may not work for everyone, or it may lose its effectiveness over time. Some people may not respond well to Zyrtec, or they may develop tolerance or resistance to it. Zyrtec may also not be enough to control severe or chronic allergies, and it may need to be combined with other treatments, such as nasal sprays, eye drops, or immunotherapy .
  • Zyrtec may be expensive, especially if it is not covered by insurance or if it is used frequently. Zyrtec may cost more than other OTC antihistamines, such as loratadine (Claritin) or fexofenadine (Allegra). Zyrtec may also be less affordable than generic versions of cetirizine, which are usually cheaper and equally effective .
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Zyrtec is a popular and effective antihistamine that can help people with allergies. Zyrtec has its cons and pros, and it may not be suitable for everyone. Zyrtec should be used as directed, and with caution in some cases. Zyrtec should not be used as a substitute for medical advice or diagnosis. Zyrtec should be used only to treat allergy symptoms, and not for other purposes. Zyrtec should be used with respect and responsibility, and not for abuse or misuse.