Antiviral therapy for herpes zoster should be started within how many hours to reduce risk of postherpetic neuralgia?

• A. Within 24 hours
• B. Within 7 days
• C. Within 72 hours
• D. No time limit

Answer: (C)

Prompt antiviral therapy for herpes zoster is most effective at reducing postherpetic neuralgia when started within 72 hours of rash onset. Early treatment limits viral replication and nerve inflammation, which helps protect against longer-lasting nerve pain. Common antivirals such as acyclovir, valacyclovir, and famciclovir are used, with the higher-benefit window being up to about 72 hours after the eruption appears. Starting therapy sooner yields the greatest reduction in risk, while beginning after this window offers diminishing protection. Choosing a plan outside this 72-hour window misses the optimal opportunity to lower the chance of chronic neuralgia.