How long after starting antibiotic therapy is a child with strep throat generally no longer contagious?

• A. 48 hours after starting antibiotics.
• B. 24 hours after starting antibiotics.
• C. Immediately after antibiotics begin.
• D. 72 hours after starting antibiotics.

Answer: (B)

Contagiousness from strep throat drops quickly once effective antibiotics are started. The bacteria causing the infection are rapidly suppressed, so after about 24 hours of antibiotic therapy, most children are no longer contagious, especially if they have no fever. This is why guidelines commonly allow return to school after 24 hours of treatment and being fever-free. Remember to finish the entire antibiotic course to fully clear the infection and prevent resistance, even though transmission risk is greatly reduced after the first day. If fever or symptoms persist beyond 24 hours, reassessment is warranted.