I’ve read the same thing as Alexis.
I had been using Claritin for 3 years until I got sick last month. I used it because my eyes would get itchy and my ears would feel like I was under water. The Claritin would help for the eyes but not the ears. When I got sick I stopped and my eyes haven’t been itchy much, which I find surprising. When they get itchy now (only twice in one month) I put an ice pack on them and it helps.
My Endo did not tell me not to use Claritin but my Primary Dr. said that it would just dry my eyes. She gave me a nasal spray instead for my ears because they constantly feel like I’m under water.
As I was writing this message, my Endo’s office called. I asked his nurse about the Claritin and she said I had to be very careful with other medications and the Methimazole and that they did not recommend I take it.
One other thing, I read on the internet that there are natural antihistamines. Now, I don’t know if it is true or not but they listed Vitamin C and Omega 3. I take flax seed with my cereal and oatmeal. It contains Omega 3 and it is really good.