Famciclovir Dosage

Medically reviewed by Drugs.com. Last updated on Aug 4, 2023.

Applies to the following strengths: 125 mg; 250 mg; 500 mg

Usual Adult Dose for:

Herpes Simplex - Mucocutaneous/Immunocompetent Host
Herpes Simplex - Mucocutaneous/Immunocompromised Host
Herpes Simplex - Suppression
Herpes Zoster
Herpes Simplex Labialis

Usual Adult Dose for Herpes Simplex - Mucocutaneous/Immunocompetent Host

Genital herpes:
Initial episode: 250 mg orally 3 times a day for 7 to 10 days has been recommended by the US Centers for Disease Control and Prevention (CDC)

Recurrent episodes: 1000 mg orally twice a day for 1 day; alternatively, 125 mg orally twice a day for 5 days has been recommended by the CDC

Famciclovir should be started at the first sign or symptom of a recurrent episode (such as tingling, burning, itching, pain, or lesion). The efficacy has not been established if started more than 6 hours after onset of symptoms or lesions.

Usual Adult Dose for Herpes Simplex - Mucocutaneous/Immunocompromised Host

Recurrent episodes of orolabial or genital herpes in HIV-infected patients: 500 mg orally twice a day for 7 days (5 to 10 days recommended by the CDC)

Famciclovir should be started at the first sign or symptom of a recurrent episode (such as tingling, burning, itching, pain, or lesion). The efficacy has not been established if started more than 48 hours after onset of symptoms or lesions.

Usual Adult Dose for Herpes Simplex - Suppression

Chronic suppression of recurrent genital herpes:
Immunocompetent patients: 250 mg orally twice a day
HIV-infected patients: 500 mg orally twice a day has been recommended by the CDC

Therapy should be continued as clinically appropriate, although the safety and efficacy of famciclovir therapy beyond 1 year have not been established.

Usual Adult Dose for Herpes Zoster

500 mg orally every 8 hours for 7 days

Famciclovir is most effective if started within 48 hours of onset of rash. The efficacy has not been established if started more than 72 hours after onset of rash.

Usual Adult Dose for Herpes Simplex Labialis

Recurrent herpes labialis: 1500 mg orally as a single dose

Famciclovir is most effective if started at the earliest sign or symptom of a cold sore (such as tingling, burning, itching, pain, or lesion).

Renal Dose Adjustments

CrCl 40 to 59 mL/min:
Recurrent genital herpes, immunocompetent patient: 500 mg orally every 12 hours for 1 day
Herpes zoster: 500 mg orally every 12 hours
Recurrent herpes labialis: 750 mg orally once as a single dose

CrCl 20 to 39 mL/min:
Recurrent genital herpes, immunocompetent patient: 500 mg orally once as a single dose
Suppression of recurrent genital herpes, immunocompetent patient: 125 mg orally every 12 hours
Recurrent orolabial and genital herpes, HIV-infected patient: 500 mg orally every 24 hours
Herpes zoster: 500 mg orally every 24 hours
Recurrent herpes labialis: 500 mg orally once as a single dose

CrCl less than 20 mL/min:
Recurrent genital herpes, immunocompetent patient: 250 mg orally once as a single dose
Suppression of recurrent genital herpes, immunocompetent patient: 125 mg orally every 24 hours
Recurrent orolabial and genital herpes, HIV-infected patient: 250 mg orally every 24 hours
Herpes zoster: 250 mg orally every 24 hours
Recurrent herpes labialis: 250 mg orally once as a single dose

Liver Dose Adjustments

Mild or moderate hepatic impairment: No adjustment recommended.
Severe hepatic impairment: Data not available

Precautions

Efficacy and safety have not been determined for initial genital herpes episodes, ophthalmic zoster, Black and African American patients with recurrent genital herpes, or immunocompromised patients other than for the treatment of recurrent orolabial or genital herpes in HIV-infected patients.

The dosage should be reduced in patients with renal dysfunction. Acute renal failure has developed in patients with renal disease who received larger than recommended doses of famciclovir.

Caution should be exercised in the administration and monitoring of famciclovir in the elderly reflecting the greater frequency of decreased renal function and concomitant use of other drugs.

Since the tablets contain lactose, individuals who have hereditary galactose intolerance, severe lactase deficiency, or glucose-galactose malabsorption should check with their healthcare provider before taking famciclovir.

Safety and efficacy have not been established in pediatric patients (less than 18 years of age).

Dialysis

Hemodialysis:
Recurrent genital herpes, immunocompetent patient: 250 mg orally as a single dose following dialysis
Suppression of recurrent genital herpes, immunocompetent patient: 125 mg orally following each dialysis
Recurrent orolabial and genital herpes, HIV-infected patient: 250 mg orally following each dialysis
Herpes zoster: 250 mg orally following each dialysis
Recurrent herpes labialis: 250 mg orally as a single dose following dialysis

Other Comments

Famciclovir may be given without regard to meals.

Patients should be aware that famciclovir is not a cure for cold sores or genital herpes. There are no data on whether it will prevent transmission of genital herpes to others.

Patients should be advised against driving or operating machinery if dizziness, somnolence, confusion, or other CNS side effects develop.