I have a seven year old. And it seems he spent most of his previous school year coughing all the time. It seemed to start every time he ate something and the cough seemed to continue. So the doctor gave him Rantidine. Before all that we gave him Zyrtec....we have been giving him Zyrtec since he was a toddler, but he always has this cough. Well he hasn't taken the rantidine or zyrtec over the summer and we just got a dog. A Cairn Terrier and of course he is all over the dog. So now I don't know if the dog has caused the coughing, allergy season or its because he needs the rantidine again. What do you suggest.
You don't mention whether he coughed over the summer when he wasn't taking the Ranitidine and Zyrtec but there are a couple of things that could be causing the cough.
It could be acid reflux, in which case getting him back on the Ranitidine should help with acid reflux and the cough, and if the cough is caused by allergies the Zyrtec should help, but it doesn't sound like those things have helped that much in the past.
One thing you don't mention is asthma, which commonly presents as a cough, and which can be aggravated by acid reflux.
To be safe you should probably take him to see a pediatric allergist or pulmonologist to get him tested for allergies and asthma so that you don't have to keep guessing about the cause of his cough.
I switched from Claritin to Zyrtec this spring. Everything was fine and it helped my allergies. After three weeks, though, I started having symptoms of acid reflux, had trouble swallowing, and was constantly coughing. I didn't put the two together since it took a few weeks for the symptoms to appear.
I started doing what I could to treat acid reflux to no avail. And then, out of desperation, I tried switching back to Claritin and off of the Zyrtec. In two days, I was back to normal. My allergies weren't treated quite as well, but it's a much better alternative than the acid reflux.