Hello Hives or rashes in an adult male may be due to these reasons , these include: 1 Urticaria , diagnosis can be confirmed by blood examination for eosinophils count. 2 Antigen antibody reactions to any allergen like dust , fungus , pollen, pests . Allergy test is useful . 3 Worm infestation also causes such type of rashes . However it is very difficult to advise any thing for local application without confirmed diagnosis . Sometimes clotrimazole lotion provide relief but it should be taken under medical expert. Prednisolone don t produces rashes but sometimes ibuprofen may produces rashes ( a side effect). Benadryl is antihistamine and it provide relief ,so you can take. In my opinion consult a dermatologist and get his opinion as physical examination is important. Good luck.