Son has rash spreading over his body itch and red what could it be?

Maybe hives?? Hives are raised itchy bumps, splotches, or welts caused by histamine, a chemical released during an allergic reaction. Blocking histamine by taking oral anti-histamine will help prevent new hives from forming, and help current hives fade away. For young toddlers, Benadryl (diphenhydramine) liquid is often used. For kids over 2 years, oral zyrtec or Claritin can also be used. A doctor can look and give a diagnosis.