Cetirizine: what it treats, how to take it, side effects
Last updated September 3, 2026.
Cetirizine is an antihistamine used to relieve allergy symptoms and hives. It works by blocking histamine, the substance your body releases that causes sneezing, itching, and watery eyes. You may know it by the brand name Zyrtec.
What does it treat?
Cetirizine treats the classic allergy picture: sneezing, runny nose, itching of the nose or throat, and red, itchy, or watery eyes. It is also used for urticaria (hives - itchy, raised red bumps on the skin). One caution from MedlinePlus: do not use it for hives that are bruised, blistered, an unusual color, or that do not itch. Those need a doctor's look instead.
How do you take it?
Cetirizine comes as a tablet, chewable tablet, capsule, dissolving tablet, and syrup. The label directs adults and children 6 and over to take one 10 mg tablet once a day, with or without food, at about the same time each day - and never more than one 10 mg tablet in 24 hours. A 5 mg product may be enough for milder symptoms. Adults 65 and over, children under 6, and people with liver or kidney disease should ask a doctor before using it. For hives, stop and call your doctor if they do not improve within the first 3 days or if they last longer than 6 weeks.
Side effects to know
- Common: drowsiness, excessive tiredness, and dry mouth.
- Serious: rash or difficulty breathing or swallowing, which needs immediate medical attention. MedlinePlus also flags a surprising one: severe itching that starts a few days after stopping cetirizine when you have taken it regularly for months or years. Call your doctor if that happens.
Who should not take it?
People with kidney or liver disease should talk to a doctor before using cetirizine, and the label says the same for adults 65 and over. Tell your doctor if you are pregnant, planning pregnancy, or breastfeeding. Because cetirizine can make you drowsy, do not drive or operate machinery until you know how it affects you - and skip alcohol while taking it, since alcohol adds to the drowsiness.
When is it an emergency?
Hives can occasionally come with anaphylaxis, a life-threatening allergic reaction. Get emergency help right away for difficulty swallowing, speaking, or breathing; swelling in or around the mouth or tongue; wheezing; drooling; dizziness; or loss of consciousness. If your doctor thinks this could happen to you, they may prescribe an epinephrine injector - cetirizine is never a substitute for it. For an overdose (restlessness, irritability, drowsiness), call Poison Control at 1-800-222-1222. Pymander's escalation routing is built and tested specifically for this class of decision; see the safety architecture working paper.
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Common questions
Does cetirizine make you sleepy?
It can. MedlinePlus lists drowsiness as one of its most common effects and advises not driving or operating machinery until you know how it affects you. Many people take it without issue, but take your first doses when you can see how your body responds.
Can I drink alcohol while taking cetirizine?
Best to skip it. MedlinePlus is direct: alcohol adds to the drowsiness cetirizine causes, so avoid alcoholic beverages while taking it.
Can I take cetirizine with food?
Yes. It can be taken once a day with or without food, at roughly the same time each day, according to MedlinePlus.
Why am I itchy after stopping cetirizine?
This is a known effect MedlinePlus warns about: some people develop severe itching within a few days of stopping cetirizine after taking it regularly for months or years. It is worth talking to your doctor if it happens to you - do not just restart and stop repeatedly without guidance.
Is cetirizine okay with kidney or liver disease?
Ask your doctor first. The FDA label specifically directs people with liver or kidney disease, and adults 65 and over, to check with a doctor before using it, because the body clears the drug more slowly in those situations.
How long should I use cetirizine for hives?
MedlinePlus gives two stopping points: call your doctor if the hives do not improve within the first 3 days of treatment, or if they last longer than 6 weeks. And if you do not know what is causing the hives, that itself is a reason to call.