If Claritin isn't working anymore, switch to Zyrtec for a while. When DD was smaller, we tried Zyrtec but it didn't agree with her so went switched to Claritin and that worked fine. This year, the Claritin wasn't working so we went back to Zyrtec and that is working great this time. Our Doc said to just go back and forth, he also said to not use things like sudafed or afrin, they don't work in the long run and in the case of afrin, can be addicitve. (DH was using sudafed and afrin, not DD!)