Generic Famvir

Common use

Famvir is an anti-viral medication which after transformation in human organism turns into penciclovir which is active against such viruses as Herpes simplex (types I and II), Varicella zoster, and the Epstein-Barr virus (EBV). Penciclovir penetrates into the cells infected by virus where being subjected to treatment by viral ferments it turns into penciclovir-triphosphate which inhibits replication of viral DNA. The medication has not effect on the non-infected cells. Famvir is active against certain strains of Herpes simplex with changed DNA polymerase which are resistant to Acyclovir (Zovirax). Famvir is administered to treat infections caused by Herpes simplex (types I and II): primal infection, aggravation of the chronic infection, prevention, shingles or chickenpox (Varicella zoster), postherpetic neuralgia, recurrent genital herpes.



Dosage and directions

Take Famvir with or without food. Take each dose with a glass of water. The recommended dose for treatment of recurrent genital herpes is 1,000 mg twice daily during one day. Recurrent cold sores should be treated by 1,500 mg taken as a single dose. To suppress recurrent genital herpes take 250 mg twice daily during 1 year. Treatment of shingles require 500 mg every eight hours for a week. In HIV-infected patients for treatment of cold sores and genital herpes 500 mg of Famvir is taken twice daily for 5-10 days. Do not take Famvir in larger amounts. Follow all recommendations of your doctor.



Precautions

Do not allow contact of the affected areas with other people. Do not touch your eyes after you touched the affected areas. Wash your hand frequently to avoid spreading of the infection to others.



Contraindications

Famvir is contraindicated in patients hypersensitive to the components of this medication, pregnant and breastfeeding women, children. Correction of the dose and certain cautiousness are needed in treatment of patients with kidney failure.



Possible side effect

The most common side effects are headache, nausea, vomiting, diarrhea, dizziness, allergic reactions. Some adult patients experience mental confusion, hallucinations. In the patients with decreased immunity pain in the stomach, fever symptoms occur.



Drug interaction

No specific interactions are known for this time.



Missed dose

If you forgot to take your dose in time, please do it as soon as you remember. But do not take if it is too late or almost time for your next dose. Do not take double or extra doses. Take your usually dose next day in the same regularly time.



Overdose

symptoms of Famvir overdose are unknown. If recommendations for treatment of the patients with kidney failure are not observed, acute kidney failure is possible. Seek for immediate medical attention if overdose is suspected.



Storage

Store at room temperature between 59-77 F (15-25 C) away from light and moisture, kids and pets. Do not use after expiration term.



Disclaimer

We provide only general information about medications which does not cover all directions, possible drug integrations, or precautions. Information at the site cannot be used for self-treatment and self-diagnosis. Any specific instructions for a particular patient should be agreed with your health care adviser or doctor in charge of the case. We disclaim reliability of this information and mistakes it could contain. We are not responsible for any direct, indirect, special or other indirect damage as a result of any use of the information on this site and also for consequences of self-treatment.

Clinical Verification

Last Clinically Updated: August 15, 2026

Written By

Dr. Elena Vance, PharmD

Clinical Specialist in Neuropharmacology

Fact Checked By

Marcus Thorne, MS

Biomedical Data & FDA Label Verification

Medically Reviewed By

Dr. Arthur Campbell, MD

Board-Certified Psychiatrist (ABPN)