 [ Symptoms ] drug allergy my husband was taking anitbiotics prescribed by a dentist for a n infection in a tooth see more below two days after finishing the prescription he developed hives and nausea he did take benedryl for the hives on an empty stomach and the nausea came on after that so i guess that could cause stomach upset but still dont know what caused the hives [ Disease ] many things can cause hives but the antibiotic he was taken even if he recently finished it is still high on the list of possibilities