Is Zyrtec ever used to relieve the symptoms of poison ivy?

Yes it can help with allergies.Also used for hey fever.

Zyrtec-D (cetirizine and pseudoephedrine) is a non-prescription ("over-the-counter") medication approved to treat the following allergy symptoms:

Nasal congestion, runny nose, sneezing itchy, or watery eyes and itchy nose or throat.

I will give you two alternatives which I believe will also help you-.

Over-the-counter medicine for poison ivy will work for many people. It is recommended that you try one of these products before going to see a doctor in mild or minor cases of outbreak. Ask your pharmacist.

TechNu--this also works well as a preventive measure when used as a lotion before coming into contact
IvyRest--this works similarly to TechNu
Benadryl--this can be taken internally

Natural cures have always been a medicine for poison ivy passed down for generations. Some of the more common natural medicines for poison ivy include the following:
Vitamin C
Baking soda and
Aloe vera
Milkweed
Jewelweed

If the rash is widespread or results in a large number of blisters, your doctor may prescribe an oral corticosteroid, such as prednisone, for poison ivy treatment. If a bacterial infection has developed at the rash site, your doctor will likely give you a prescription for an oral antibiotic.

I hope this helps