Hi,what is the difference between claritin s, loratadine, ,zyrtec s cetirizine,, and Benadryl s Diphenhydramine?????? I have a sore throat, (took tylenl as needed)) and some coughing. Doctor said it was a post-nasal drip ,was losing voice, he said take Benadryl. I talked to pharmacy And she said. Claritin, and robitussin for cough as needed. Found Benadryl wasn t helpful, it has been a week Since stared throat and cough meds that doctor recommended. I just took 1 Claritin at 5:30 tonight. Appreciate your advice. Terry