Dear user, The last part of your question is something I wouldn t care to try. Self-medication is ALWAYS wrong, whether taken internally or applied over the skin. I think he may be having a viral rash, though it might be difficult to say which one without seeing it. If he is otherwise okay, applying calamine lotion alone may be enough. If, however, he has high fever, or if the rash keeps increasing, you should go to his doctor within the next four hours. P.S. Do the rash areas look like mosquito or insect bites? If so, calamine will still help. Dr. Taher