Can my 9 year old son take Clarithromycin and Benadryl? He had some minor viral hives before starting the Clarithromycin today, but 3 hrs after taking it, he took a very warm shower, and about 15 minutes after drying off, his hives got much worse. So we thought maybe he could take Benadryl to help, but we are unsure of the drug interaaction. Thank you.