Cetirizine is a second-generation antihistamine widely used to relieve symptoms associated with seasonal and perennial allergies, as well as chronic urticaria (hives). It is available over-the-counter in many countries, often marketed under brand names such as Zyrtec. As an antihistamine, cetirizine works by blocking the action of histamine, a natural substance in the body that causes allergic symptoms. Unlike older first-generation antihistamines, cetirizine is less likely to cause drowsiness, though some individuals may still experience this side effect. It is typically taken orally and is known for its relatively rapid onset of action and once-daily dosing convenience. (NIH ODS)
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Known interactions
Category rule: supplement × medication
Note
Some supplements change how the body processes medications (absorption, liver enzymes, or additive effects).
Specific pairs are checked against a licensed drug database and shown with their own severity. Always confirm with your provider or pharmacist.
Category rule: vitamin × medication
Note
Certain vitamins interact with specific medications (e.g., vitamin K with blood thinners).
Specific pairs are checked against a licensed source; confirm with your provider.
Frequently asked
Sources referenced
["NIH Office of Dietary Supplements (ODS)", "MedlinePlus", "PubChem", "Mayo Clinic", "FDA label (for Zyrtec and generic Cetirizine)", "EMA SmPC (Summary of Product Characteristics)", "Cochrane Database of Systematic Reviews", "DrugBank"]
Stackwise compiles summaries from publicly available scientific and regulatory references. Always verify important decisions with a licensed clinician.
Related compounds
Others in the medication category or studied for the same goals.
