Yes, it can. The Zyrtec Allergy label's own warnings say drowsiness may occur, and MedlinePlus says cetirizine - Zyrtec's active ingredient - may make you drowsy, so do not drive until you know how it affects you.
This page is about Zyrtec Allergy 10 mg tablets (cetirizine HCl); if your box lists different active ingredients, its own Drug Facts label is the one that applies.
What the label says
Zyrtec Allergy tablets have one active ingredient - cetirizine HCl 10 mg, an antihistamine. The drowsiness question is answered by three sources: the product's own label, MedlinePlus's cetirizine page, and the NHS cetirizine side-effects page:
Who should ask a doctor first
The Zyrtec Allergy label says do not use it if you have ever had an allergic reaction to this product or any of its ingredients, or to an antihistamine containing hydroxyzine.
The label says to ask a doctor before use if you have liver or kidney disease - your doctor should determine if you need a different dose - and its directions say adults 65 years of age and older, and children under 6 years of age, should ask a doctor before use.
If you are pregnant, the label says to ask a health professional before use, and MedlinePlus says to call your doctor if you become pregnant while taking cetirizine; the label says breastfeeding is not recommended while taking it. MedlinePlus also lists itching that starts a few days after stopping cetirizine taken regularly for months or years among the effects to call your doctor about immediately - if you have been taking it regularly for that long, talk to your doctor about that risk. A pharmacist or your prescriber is the right reviewer for your full medication list. An AI consult can help you work out what to ask; it is not a substitute for that review.
Common questions
Does Zyrtec make you drowsy?
It can. The Zyrtec Allergy label's own warnings say drowsiness may occur, and MedlinePlus lists drowsiness and excessive tiredness among cetirizine's possible side effects. Possible is not guaranteed. The label says to be careful when driving or operating machinery; MedlinePlus says do not drive until you know how this medication affects you.
Can I drive after taking Zyrtec?
The label says to be careful when driving a motor vehicle or operating machinery. MedlinePlus says do not drive a car or operate machinery until you know how this medication affects you.
Can I drink alcohol with Zyrtec?
The label says to avoid alcoholic drinks, and warns that alcohol, sedatives, and tranquilizers may increase drowsiness. MedlinePlus says alcohol can add to the drowsiness caused by cetirizine and to avoid drinking alcoholic beverages while taking it.
Can Zyrtec keep you awake?
None of the sources checked for this page - the Zyrtec Allergy label, MedlinePlus's cetirizine page, and the NHS cetirizine side-effects page - lists sleeplessness among its warnings or possible side effects. That absence does not prove it cannot happen; if you notice unexpected or persistent sleep changes while taking it, ask a pharmacist or your doctor.
Does this apply to every Zyrtec product?
This page covers Zyrtec Allergy 10 mg tablets (cetirizine HCl) only. Other products carry the Zyrtec name with different active ingredients - Zyrtec-D, for example, adds pseudoephedrine. Check the Drug Facts on your own box - the active ingredients listed there are the label that applies to it.