Can prolonged use of Benedryl and Zyrtec cause unwanted effects on the tongue? My son (14yrs) has been taking Benedryl frequently for the last 16 weeks to reduce severe allergic symptoms associated with his initial set of (simultaneous) venom and grass/pollen/mold/dust/etc. allergy shots. Over the past four days he has been having an increasingly sore and sensitive tongue. It has begun to be slightly reddened and slick looking in places. No antibiotics. No other medications except occasional Tums. I wondered if the two things (sore tongue&lots of Benedryl) might be connected. Would call his allergist, but everybody s out for the holidays.