Classes Antiinfective Agent
Antiviral Agent
Dermatological/Topical Agent
Topical Antiinfective Agent
Purine Nucleoside
Diseases Herpes
Infectious Disease


Acyclovir is a guanosine analogue antiviral drug. Acyclovir is converted to triphosphate form which inhibits viral DNA polymerase competitively by acting as an analog to deoxyguanosine triphosphate (dGTP). Acyclovir triphosphate incorporation into DNA results in chain termination because the lack of a 3' hydroxyl group prevents the attachment of additional nucleosides.

Acyclovir is indicated for the following infectious diseases-

  • Herpes Zoster Infections (Shingles)
  • Genital Herpes
  • Chickenpox
  • 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. 
    • Intermittent Therapy: 200 mg every 4 hours, 5 times daily for 5 days. Therapy should be initiated at the earliest sign or symptom (prodrome) of recurrence.
  • Treatment of Chickenpox:
    • Children (2 years of age and older): 20 mg/kg per dose orally 4 times daily (80 mg/kg/day) for 5 days. Children over 40 kg should receive the adult dose for chickenpox.
    • Adults and Children over 40 kg: 800 mg 4 times daily for 5 days. Intravenous Acyclovir is indicated for the treatment of varicella-zoster infections in immunocompromised patients.

When therapy is indicated, it should be initiated at the earliest sign or symptom of chickenpox. There is no information about the efficacy of therapy initiated more than 24 hours after onset of signs and symptoms. 




The most common adverse reaction are-

  • Nausea
  • Vomiting
  • Diarrhea
  • anaphylaxis
  • angioedema
  • fever
  • headache
  • pain
  • peripheral edema.


  • Acyclovir Capsules, Tablets, and Suspension are only for oral use. Acyclovir therapy has been associated with renal failure, which has resulted in death in some cases. In immunocompromised patients receiving acyclovir therapy, thrombotic thrombocytopenic purpura/hemolytic uremic syndrome (TTP/HUS) has resulted in death.
  • When administering Acyclovir to patients with renal impairment, dosage should be adjusted. Caution should also be exercised when administering Acyclovir to patients receiving potentially nephrotoxic agents, as this may increase the risk of renal dysfunction and/or reversible central nervous system symptoms, similar to those reported in patients receiving intravenous acyclovir. Maintaining adequate hydration is essential.
  • Patients are advised to contact their doctor if they have severe or bothersome adverse reactions, become pregnant or intend to become pregnant, plan to breastfeed while taking orally administered Acyclovir, or have any other questions. Patients should be encouraged to stay hydrated.
  • There is no information on treatment begun more than 72 hours after the onset of the zoster rash. Patients should be advised to begin treatment as soon as possible after a herpes zoster diagnosis.
  • Acyclovir is not a cure for genital herpes, and patients should be informed of this. There is no evidence that Acyclovir will prevent infection transmission to others. To avoid infecting partners, patients should avoid contact with lesions or intercourse when lesions and/or symptoms are present. Asymptomatic viral shedding can also transmit genital herpes in the absence of symptoms. If medical treatment is recommended for a genital herpes recurrence, patients should be advised to begin treatment at the first sign or symptom of an episode.
  • Chickenpox in otherwise healthy children is usually a self-limited disease of mild to moderate severity. Adolescents and adults tend to have more severe disease. Treatment was initiated within 24 hours of the typical chickenpox rash in the controlled studies, and there is no information regarding the effects of treatment begun later in the disease course.