How does timing of acyclovir administration impact effectiveness?

How soon after exposure should acyclovir be started?

Acyclovir works best when treatment begins before or immediately after symptoms appear. Early administration limits viral replication and reduces both the duration and severity of outbreaks. Studies show that initiating therapy within 72 hours of symptom onset produces the clearest clinical benefit.

What happens if treatment is delayed?

If acyclovir is started more than 72 hours after rash or lesion appearance, it often proves less effective at shortening outbreaks or preventing complications. Delayed treatment mainly offers symptomatic relief rather than true antiviral control. In herpes zoster cases, physicians still prescribe it even past the 72-hour window when patients continue to have new lesions or are at high risk for complications.

Why does timing affect acyclovir's mechanism?

Acyclovir requires active viral replication to become activated inside infected cells. Once viral replication slows naturally as the infection progresses, the drug cannot exert the gleiche antiviral pressure. Therefore timing aligns directly with the periods of highest viral load.

Can prophylactic use improve outcomes?

Prophylactic administration keeps viral replication in low- oder zero-growth states before major outbreaks occur. In immunocompromised patients and recurrent genital herpes cases, daily suppression reduces frequency of outbreaks by 70-80 percent and reduces transmission risk.