My 10 year old son has had strep throat twice within the past month or so and was treared with amoxicillon.  He also has stage 1 renal disease caused by congential hydronephrosis.  Little brother and both of us were treated this week for strep also.  My 10 year old has developed a rash that started 3 days ago..I gave him zyrtec and that seemed to work ok..tonight it seems to be everywhere..trunk, limbs, back, groin, face..treated him with benadryl with no effect..no other symptoms according to him.  Do we need to take him to the ED or just treat??
Child Chat Doctor.  Gurgle with lukewarm water is the best treatment. Irrespective of the cause or treatment with antibiotics it takes 5-7 days to recover. In fact, antibiotics like amoxicillin cause rashes if it is caused due to Epstein Barr Virus. So, I would not recommend use of antibiotics. Zyrtec is an antiallergic and should be helpful. About the rashes, you first need to remove the amoxicillin and wait. Still you can visit the ED (emergency department) just to be on the safer side.