I haven't posted here in a looong time. Not since Toddy passed away. I thought this might be a good place to ask this question. I have a 6 year old kitty (Olivia) She's pretty healthy overall, though for a few years she has had days where she is sneezy and has a runny nose all day long. The vet assumed herpes, but she is not having all the symptoms, and the supplements don't really do anything. Anyway, she went in for her check up today and we discussed the runny nose. The vet now thinks maybe allergies. Her suggestion was 5mg of Cetirizine (Zyrtec). We were both unsure of a few things and her medical books were not helpful in answering the following questions... 1) can we just use human Zyrtec (the plain one. No D) ? 2) They don't make a 5mg tablet. can I cut a 10mg tablet in half? 3) Do I use 12 hour or 24 hour. (not sure they still make 12 hour even) 4) If I use 24 hour, is it time release? Will cutting it in half decrease the effectiveness of the medication or cause any issues? 5) Any side effects I should be worried about? I've tried doing some online research, but I'm getting mostly stuff about humans taking Zyrtec for cat allergies OR stuff saying Zyrtec might be bad. Very little helpful info. Thank you!