Cetirizine

Allergy

Also known as Zyrtec

Cetirizine is an antihistamine. When allergies hit, your body releases a chemical called histamine — that's what makes you sneeze, itch, and drip. Cetirizine blocks histamine so those symptoms quiet down. It's considered a non-drowsy antihistamine, but honest truth: it makes some people a little sleepy, more so than loratadine or fexofenadine.

How to take it

When

Once a day, any time that's easy to remember. It starts working within about an hour and lasts a full 24 hours.

Food

With or without food — either is fine.

Avoid

Go easy on alcohol, and see how it affects you before driving — a small number of people feel drowsy on it.

Good to know

If you've taken it daily for months and want to stop, some people get intense itching for days after stopping. It passes, but it's real — mention it to your doctor if it happens.

Missed a dose?

If you take it daily and miss a dose, take it when you remember. If it's almost time for the next one, just skip the missed dose. Never double up.

Common side effects

Mild drowsiness or tiredness
Dry mouth
Headache
Stomach upset

Call a doctor if

Trouble breathing or swallowing, or swelling of your face, lips, or tongue — call emergency services now. An allergy pill is not a substitute for epinephrine in a severe reaction.
Hives spreading fast along with dizziness or throat tightness — get emergency help
Severe drowsiness or confusion
Trouble urinating

Educational only. This summary is drawn from public FDA labeling and MedlinePlus and simplified for readability. Your prescription label and your pharmacist always come first — doses and instructions vary from person to person.