Shingles treatment can be costly. Antiviral medicines are most effective within 72 hours of the onset of the rash. However, they may not be helpful if the new blisters appear. Antiviral medication should only be used for one week. Your healthcare provider will recommend that you follow the instructions. If your child develops shingles, ask your doctor about treatment options. Antiviral medication can be used to reduce the pain and speed up healing if your child is suffering from mild shingles.