will giving antiviral agent like valacyclovir later than 72 hours upon start of herpes zoster still effective?

will giving antiviral agent like valacyclovir later than 72 hours upon start of herpes zoster still effective?

It may, and it may not.

Valacyclovir, for herpes zoster, should actually be taken within 48 hours of the onset of a rash to be most effective, though the clinical studies performed started treatment within 72 hours (*info on the package insert)it will shorten the duration and severity of the attack.

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