伐昔洛韦（Valaciclovir）是鸟嘌呤类似物类抗病毒药物，用于单纯疱疹和带状疱疹感染。它是阿昔洛韦的前药，在体内可转化为阿昔洛韦。

伐昔洛韦是一种前药，是阿昔洛韦酯化物，口服生物利用度（约55%）显着高于阿昔洛韦（10-20%）。在体内通过首过效应被酯酶转化为阿昔洛韦，从而起到抗病毒作用。

Valaciclovir (INN) or valacyclovir (USAN) is an antiviral drug used in the management of herpes simplex, herpes zoster (shingles), and herpes B. It is a prodrug, being converted in vivo to aciclovir. It is marketed by GlaxoSmithKline under the trade names Valtrex and Zelitrex. Valaciclovir has been available as a generic drug in the U.S. since November 25, 2009.