Cetirizine is an antihistamine that can help manage allergic reactions by blocking the effects of histamine, a substance the body releases during an allergic response [1]. It is commonly used to relieve symptoms such as sneezing, runny nose, itchy or watery eyes, and itching of the nose or throat [2].
How does cetirizine work for allergies?
Cetirizine is a second-generation antihistamine that selectively antagonizes peripheral H1 receptors [3]. By blocking these receptors, it prevents histamine from binding and causing allergic symptoms [3]. Unlike older antihistamines, it is less likely to cause drowsiness because it does not readily cross the blood-brain barrier [4].
When can I expect cetirizine to start working?
Cetirizine typically begins to relieve allergy symptoms within one hour of taking it [5]. The full effect may take a few hours, and it provides relief for up to 24 hours per dose [5].
How does cetirizine compare to other allergy medications?
Cetirizine is an oral antihistamine, and its effectiveness is comparable to other second-generation antihistamines like loratadine and fexofenadine [6]. These medications differ from first-generation antihistamines (e.g., diphenhydramine) primarily in their reduced sedative effects [4]. Some individuals may find one antihistamine works better for them than another due to variations in personal response [7].
Are there any side effects of cetirizine I should know about?
Common side effects of cetirizine can include drowsiness, dry mouth, fatigue, and sore throat [8]. While less sedating than older antihistamines, some people still experience drowsiness [4]. It is important to use caution when driving or operating machinery until you know how cetirizine affects you [8].
Can children take cetirizine for allergies?
Cetirizine is available in formulations suitable for children, typically for those aged 6 months and older, depending on the specific product and dosage instructions [9]. Always consult a pediatrician before giving any medication to a child [9].
What if cetirizine doesn't fully relieve my allergic reaction?
If cetirizine does not adequately relieve allergy symptoms, other treatment options may be considered, such as nasal corticosteroids or other oral antihistamines [7]. In severe allergic reactions, immediate medical attention is necessary, as this may indicate anaphylaxis, which requires emergency treatment [10].
When does the patent for cetirizine expire?
Cetirizine (Zyrtec) is an older medication, and its primary patents have long expired, allowing for the widespread availability of generic versions [11]. This is why cetirizine is readily available over-the-counter and is generally affordable [11].
Sources:
[1] https://www.nhs.uk/medicines/cetirizine/
[2] https://www.drugs.com/cetirizine.html
[3] https://www.ncbi.nlm.nih.gov/books/NBK557807/
[4] https://www.webmd.com/allergies/features/allergy-medications-guide
[5] https://www.healthline.com/health/allergies/cetirizine-over-the-counter
[6] https://www.mayoclinic.org/diseases-conditions/hay-fever/in-depth/allergy-medications/art-20047417
[7] https://www.allergy.org.au/patients/allergic-rhinitis-hay-fever/treatment-of-allergic-rhinitis
[8] https://www.rxlist.com/zyrtec-side-effects-drug-center.htm
[9] https://www.webmd.com/drugs/2/drug-6340/cetirizine-oral/details
[10] https://www.niaid.nih.gov/diseases-conditions/anaphylaxis
[11] https://www.drugpatentwatch.com/