My son has a raised rash on the backs of each hand and elbows, which he has had since yesterday. He has had a similar rash many times before when playing in grass. He has been playing soccer on grass turf all week. My husband gave him one loratadine (active ingredient - 10 mg) tablet 2 hours ago because he could not find benedryl (diphenhydramine hydrochloride) at the time. I have the benedryl, can he take some now (2-4 tablets - 12.5 mg). If yes, how much? If no, when can he take benedryl.