Aciclovir

What it is and how it works

Mechanism class: DNA Polymerase Inhibitors

Indications

INDICATIONS AND USAGE Herpes Zoster Infections: Acyclovir tablets, USP are indicated for the acute treatment of herpes zoster (shingles). Genital Herpes: Acyclovir tablets, USP are indicated for the treatment of initial episodes and the management of recurrent episodes of genital herpes. Chickenpox: Acyclovir tablets, USP are indicated for the treatment of chickenpox (varicella).

Dosage and administration (summary)

DOSAGE AND ADMINISTRATION Acute Treatment of Herpes Zoster: 800 mg every 4 hours orally, 5 times daily for 7 to 10 days. Genital Herpes: Treatment of Initial Genital Herpes: 200 mg every 4 hours, 5 times daily for 10 days. Chronic Suppressive Therapy for Recurrent Disease: 400 mg 2 times daily for up to 12 months, followed by re-evaluation. Alternative regimens have included doses ranging from 200 mg 3 times daily to 200 mg 5 times daily. The frequency and severity of episodes of untreated genital herpes may change over time.

Contraindications

CONTRAINDICATIONS Acyclovir tablets are contraindicated in patients who have had a demonstrated clinically significant hypersensitivity reaction [e.g., anaphylaxis, severe cutaneous adverse reactions (SCARs)] to acyclovir, valacyclovir, or any component of the formulation (see WARNINGS and ADVERSE REACTIONS ).

Warnings and precautions

WARNINGS Acyclovir tablets are intended for oral ingestion only. Renal failure, in some cases resulting in death, has been observed with acyclovir therapy (see ADVERSE REACTIONS: Observed During Clinical Practice and OVERDOSAGE ). Thrombotic thrombocytopenic purpura/hemolytic uremic syndrome (TTP/HUS), which has resulted in death, has occurred in immunocompromised patients receiving acyclovir therapy.

Pregnancy

Pregnancy: Teratogenic Effects: Pregnancy Category B. Acyclovir administered during organogenesis was not teratogenic in the mouse (450 mg/kg/day, p.o.), rabbit (50 mg/kg/day, s.c. and IV), or rat (50 mg/kg/day, s.c.). These exposures resulted in plasma levels 9 and 18, 16 and 106, and 11 and 22 times, respectively, human levels.

Storage and supply

HOW SUPPLIED Acyclovir tablets USP, 800 mg containing 800 mg of acyclovir USP are blue, oval, biconvex tablets debossed with 'J' on one side and '50' on the other side. They are supplied as follows: Bottles of 100 tablets NDC 31722-778-01 Bottles of 500 tablets NDC 31722-778-05 Acyclovir tablets USP, 400 mg containing 400 mg of acyclovir USP are pi…

Source: Acyclovir (Acyclovir) — US FDA prescribing information, 2026-02-02, DailyMed. Summarised and shortened; the full label governs. Iranian registration, indications and labelling may differ.