Zyrtec
Reactine (in some countries)
Second-generation antihistamine (H1-receptor antagonist)
Cetirizine dihydrochloride is used to treat allergic conditions, including:
Allergic rhinitis (hay fever, pollen allergy)
Chronic idiopathic urticaria (long-term hives)
Seasonal and perennial allergies
Itchy skin, runny nose, sneezing, watery eyes
It works by blocking histamine H1 receptors, preventing the effects of histamine a chemical involved in allergic reactions.
Unlike first-generation antihistamines (like diphenhydramine), cetirizine does not readily cross the blood-brain barrier, so it causes less drowsiness.
5 to 10 mg once daily (depending on severity and age)
Lower doses are recommended for children or those with kidney impairment
Common: Headache, dry mouth, mild drowsiness, fatigue
Less common: Stomach pain, dizziness
Molecular Formula: CHClNO
Molecular Weight: 461.81 g/mol
CAS Number: 83881-52-1
Appearance: White or off-white crystalline powder
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