Can you take cetirizine hcl and hydroxyzine hcl together?

You can take these drugs together, but probably shouldn't. They do not interact, but both have similar actions, so taking one dose of each of them at the same time (that is, one dose of cetirizine and one dose of chlorpheniriamine) would probably be like taking either two cetirizine or two chlorphenirimine in the effect it had (in other Words it'd be like taking a small overdose of either of these medications). This is not advisible, as these medications can cause drowsiness and other side-effects.

They each also have other side-effects unique to each drug, so taking these two medications at the same time also can mean that you're exposing yourself to more potential side-effects than if you just take one of them. Additionally, just taking one type of medication means that you would know which one it was that was causing the side-effects, should any occur.

Basically, I'd say it'd be a bad idea to take these drugs simultaneously. If you find that one drug, at the normal dose, is not enough, then I'd suggest consulting a pharmacist or doctor.