Famciclovir

Do not take it if

Quoted from the official label, section “Contraindications”.

How to take it

These directions are for this exact strength and form. Another one is different.

• Famciclovir tablets may be taken with or without food.
• Immunocompetent Adult Patients ( 2.1 ) Herpes labialis (cold sores) 1500 mg as a single dose Genital herpes Treatment of recurrent episodes Suppressive therapy 1000 mg twice daily for 1 day 250 mg twice daily Herpes zoster (shingles) 500 mg every 8 hours for 7 days HIV-Infected Adult Patients ( 2.2 ) Recurrent episodes of orolabial or genital herpes 500 mg twice daily for 7 days Patients with renal impairment:
• Adjust dose based on creatinine clearance.
• ( 2.3 )
• 2.1 Dosing Recommendation in Immunocompetent Adult Patients Herpes labialis (cold sores):
• The recommended dosage of famciclovir tablets for the treatment of recurrent herpes labialis is 1500 mg as a single dose.
• Therapy should be initiated at the first sign or symptom of herpes labialis (e.g., tingling, itching, burning, pain, or lesion).
• Genital herpes:
• Recurrent episodes:
• The recommended dosage of famciclovir tablets for the treatment of recurrent episodes of genital herpes is 1000 mg twice daily for 1 day.
• Therapy should be initiated at the first sign or symptom of a recurrent episode (e.g., tingling, itching, burning, pain, or lesion).
• Suppressive therapy:
• The recommended dosage of famciclovir tablets for chronic suppressive therapy of recurrent episodes of genital herpes is 250 mg twice daily.
• Herpes zoster (shingles):
• The recommended dosage of famciclovir tablets for the treatment of herpes zoster is 500 mg every 8 hours for 7 days.
• Therapy should be initiated as soon as herpes zoster is diagnosed.
• 2.2 Dosing Recommendation in HIV-Infected Adult Patients Recurrent orolabial or genital herpes:
• The recommended dosage of famciclovir tablets for the treatment of recurrent orolabial or genital herpes in HIV-infected patients is 500 mg twice daily for 7 days.
• Therapy should be initiated at the first sign or symptom of a recurrent episode (e.g., tingling, itching, burning, pain, or lesion).
• 2.3 Dosing Recommendation in Patients with Renal Impairment Dosage recommendations for adult patients with renal impairment are provided in Table 1 [ see Use in Specific Populations (8.6) , Clinical Pharmacology (12.3) ] .
• Table 1:
• Dosage Recommendations for Adult Patients with Renal Impairment * Hemodialysis Indication and Normal Dosage Regimen Creatinine Clearance (mL/min) Adjusted Dosage Regimen Dose (mg) Dosing Interval Single-Day Dosing Regimens Recurrent Genital Herpes 1000 mg every 12 hours for 1 day ≥ 60 1000 every 12 hours for 1 day 40 to 59 500 every 12 hours for 1 day 20 to 39 500 single dose < 20 250 single dose HD * 250 single dose following dialysis Recurrent Herpes Labialis 1500 mg single dose ≥ 60 1500 single dose 40 to 59 750 single dose 20 to 39 500 single dose < 20 250 single dose HD* 250 single dose following dialysis Multiple-Day Dosing Regimens Herpes Zoster 500 mg every 8 hours ≥ 60 500 every 8 hours 40 to 59 500 every 12 hours 20 to 39 500 every 24 hours < 20 250 every 24 hours HD* 250 following each dialysis Suppression of Recurrent Genital Herpes 250 mg every 12 hours ≥ 40 250 every 12 hours 20 to 39 125 every 12 hours < 20 125 every 24 hours HD * 125 following each dialysis Recurrent Orolabial or Genital Herpes in HIV-Infected Patients 500 mg every 12 hours ≥ 40 500 every 12 hours 20 to 39 500 every 24 hours < 20 250 every 24 hours HD * 250 following each dialysis

Quoted from the official label, section “Dosage & Administration”.

Other warnings

Quoted from the official label, section “Warnings”.

Pregnancy and breastfeeding

Quoted from the official label, section “OTC — Pregnancy or Breast Feeding”.

Other medicines

Quoted from the official label, section “Drug Interactions”.

If you take too much

In an emergency, call your local emergency number or a poison control centre.

Quoted from the official label, section “Overdosage”.

Use in children

• The efficacy of famciclovir has not been established in pediatric patients.
• The pharmacokinetic profile and safety of famciclovir (experimental granules mixed with OraSweet ® or tablets) were studied in 3 open-label studies.
• Study 1 was a single-dose pharmacokinetic and safety study in infants 1 month to less than 1 year of age who had an active herpes simplex virus (HSV) infection or who were at risk for HSV infection.
• Eighteen subjects were enrolled and received a single dose of famciclovir experimental granules mixed with OraSweet based on the patient’s body weight (doses ranged from 25 mg to 175 mg).
• These doses were selected to provide penciclovir systemic exposures similar to the penciclovir systemic exposures observed in
• adults after administration of 500 mg famciclovir.
• The efficacy and safety of famciclovir have not been established as suppressive therapy in infants following neonatal HSV infections.
• In addition, the efficacy cannot be extrapolated from
• adults to infants because there is no similar disease in
• adults.
• Therefore, famciclovir is not recommended in infants.
• Study 2 was an open-label, single-dose pharmacokinetic, multiple-dose safety study of famciclovir experimental granules mixed with OraSweet in
• children 1 to less than 12 years of age with clinically suspected HSV or varicella zoster virus (VZV) infection.
• Fifty-one subjects were enrolled in the pharmacokinetic part of the study and received a single body weight adjusted dose of famciclovir (doses ranged from 125 mg to 500 mg).
• These doses were selected to provide penciclovir systemic exposures similar to the penciclovir systemic exposures observed in
• adults after administration of 500 mg famciclovir.
• Based on the pharmacokinetic data observed with these doses in children, a new weight-based dosing algorithm was designed and used in the multiple-dose safety part of the study.
• Pharmacokinetic data were not obtained with the revised weight-based dosing algorithm.
• A total of 100 patients were enrolled in the multiple-dose safety part of the study; 47 subjects with active or latent HSV infection and 53 subjects with chickenpox.
• Patients with active or latent HSV infection received famciclovir twice a day for 7 days.
• The daily dose of famciclovir ranged from 150 mg to 500 mg twice daily depending on the patient’s body weight.
• Patients with chickenpox received famciclovir three times daily for 7 days.
• The daily dose of famciclovir ranged from 150 mg to 500 mg three times daily depending on the patient’s body weight.
• The clinical adverse events and laboratory test abnormalities observed in this study were similar to these seen in
• adults.
• The available data are insufficient to support the use of famciclovir for the treatment of
• children 1 to less than 12 years of age with chickenpox or infections due to HSV for the following reasons:
• Chickenpox:
• The efficacy of famciclovir for the treatment of chickenpox has not been established in either pediatric or adult patients.
• Famciclovir is approved for the treatment of herpes zoster in adult patients.
• However, extrapolation of efficacy data from
• adults with herpes zoster to children with chickenpox would not be appropriate.
• Although chickenpox and herpes zoster are caused by the same virus, the diseases are different.
• Genital herpes: Clinical information on genital herpes in children is limited.
• Therefore, efficacy data from adults cannot be extrapolated to this population.
• Further, famciclovir has not been studied in
• children 1 to less than 12 years of age with recurrent genital herpes.
• None of the children in Study 2 had genital herpes.
• Herpes labialis:
• There are no pharmacokinetic and safety data in
• children 1 to less than 12 years of age to support a famciclovir dose that provides penciclovir systemic exposures comparable to the penciclovir systemic exposures in
• adults after a single dose administration of 1500 mg.
• Moreover, no efficacy data have been obtained in
• children 1 to less than 12 years of age with recurrent herpes labialis.
• Study 3 was an open-label, single-arm study to evaluate the pharmacokinetics, safety, and antiviral activity of a single 1500 mg dose (three 500 mg tablets) of famciclovir in children 12 to less than 18 years of age with recurrent herpes labialis.
• A total of 53 subjects were enrolled in the study; 10 subjects in the pharmacokinetic part of the study and 43 subjects in the non-pharmacokinetic part of the study.
• All enrolled subjects weighed greater than or equal to 40 kg.
• The 43 subjects enrolled in the non-pharmacokinetic part of the study had active recurrent herpes labialis and received a single 1500 mg dose of famciclovir within 24 hours after the onset of symptoms (median time to treatment initiation was 21 hours).
• The safety profile of famciclovir observed in this study was similar to that seen in
• adults.
• The median time to healing of patients with non-aborted lesions was 5.9 days.
• In a phase 3 trial in
• adults in which patients received a single 1500 mg dose of famciclovir or placebo, the median time to healing among patients with non-aborted lesions was 4.4 days in the famciclovir 1500 mg single-dose group and 6.2 days in the placebo group.
• Of note, in the adult study treatment was initiated by patients within 1 hour after the onset of symptoms [see Clinical Studies (14.1) ].
• Based on the efficacy results in Study 3, famciclovir is not recommended in children 12 to less than 18 years of age with recurrent herpes labialis.

Quoted from the official label, section “Pediatric Use”.

Use in older people

• Of 816 patients with herpes zoster in clinical studies who were treated with famciclovir, 248 (30.4%) were greater than or equal to 65 years of age and 103 (13%) were greater than or equal to 75 years of age.
• No overall differences were observed in the incidence or types of adverse events between younger and older patients.
• Of 610 patients with recurrent herpes simplex (type 1 or type 2) in clinical studies who were treated with famciclovir, 26 (4.3%) were greater than 65 years of age and 7 (1.1%) were greater than 75 years of age.
• Clinical studies of famciclovir in patients with recurrent genital herpes did not include sufficient numbers of subjects aged 65 years and over to determine whether they respond differently compared to younger subjects.
• No famciclovir dosage adjustment based on age is recommended unless renal function is impaired [ see Dosage and Administration (2.3) , Clinical Pharmacology (12.3) ] .
• In general, appropriate caution should be exercised in the administration and monitoring of famciclovir in elderly patients reflecting the greater frequency of decreased renal function and concomitant use of other drugs.

Quoted from the official label, section “Geriatric Use”.

Side effects

• Acute renal failure is discussed in greater detail in other sections of the label [ see Warnings and Precautions (5) ].
• The most common adverse events reported in at least 1 indication by greater than 10% of adult patients treated with famciclovir are headache and nausea.
• The most common adverse events reported in at least 1 indication by greater than 10% of adult patients are headache and nausea.
• (6.1) To report SUSPECTED ADVERSE REACTIONS, contact Rising Pharmaceuticals, Inc. at 1-866-562-4597 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.
• 6.1 Clinical Trials Experience in Adult Patients Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared with rates in the clinical trials of another drug and may not reflect the rates observed in practice.
• Immunocompetent patients:
• The safety of famciclovir has been evaluated in active- and placebo-controlled clinical studies involving 816 famciclovir-treated patients with herpes zoster (famciclovir, 250 mg three times daily to 750 mg three times daily); 163 famciclovir-treated patients with recurrent genital herpes (famciclovir, 1000 mg twice daily); 1,197 patients with recurrent genital herpes treated with famciclovir as suppressive therapy (125 mg once daily to 250 mg three times daily) of which 570 patients received famciclovir (open-labeled and/or double-blind) for at least 10 months; and 447 famciclovir-treated patients with herpes labialis (famciclovir, 1500 mg once daily or 750 mg twice daily).
• Table 2 lists selected adverse events.
• Table 2:
• Selected Adverse Events (all grades and without regard to causality) Reported by Greater Than or Equal to 2% of Patients in Placebo-Controlled Famciclovir Trials * * Patients may have entered into more than one clinical trial. † 7 days of treatment ‡ 1 day of treatment § daily treatment Incidence Events Herpes Zoster † Recurrent Genital Herpes‡ Genital Herpes-Suppression§ Herpes Labialis‡ Famciclovir (n=273) % Placebo (n=146) % Famciclovir (n=163) % Placebo (n=166) % Famciclovir (n=458) % Placebo (n=63) % Famciclovir (n=447) % Placebo (n=254) % Nervous System Headache 22.7 17.8 13.5 5.4 39.3 42.9 8.5
• 6.7 Paresthesia 2.6 0 0 0 0.9 0 0 0 Migraine 0.7 0.7 0.6 0.6 3.1 0 0.2 0 Gastrointestinal Nausea 12.5 11.6 2.5 3.6 7.2 9.5 2.2
• 3.9 Diarrhea 7.7 4.8 4.9 1.2 9 9.5 1.6
• 0.8 Vomiting 4.8 3.4 1.2 0.6 3.1 1.6 0.7 0 Flatulence 1.5 0.7 0.6 0 4.8 1.6 0.2 0 Abdominal Pain 1.1 3.4 0 1.2 7.9 7.9 0.2
• 0.4 Body as a Whole Fatigue 4.4 3.4 0.6 0 4.8 3.2 1.6
• 0.4 Skin and Appendages Pruritus 3.7 2.7 0 0.6 2.2 0 0 0 Rash 0.4 0.7 0 0 3.3 1.6 0 0 Reproductive (Female) Dysmenorrhea 0 0.7 1.8 0.6 7.6 6.3 0.4 0 Table 3 lists selected laboratory abnormalities in genital herpes suppression trials.
• Table 3:
• Selected Laboratory Abnormalities in Genital Herpes Suppression Studies * *Percentage of patients with laboratory abnormalities that were increased or decreased from baseline and were outside of specified ranges. † n values represent the minimum number of patients assessed for each laboratory parameter.
• NRH=Normal Range High.
• NRL=Normal Range Low.
• Parameter Famciclovir (n=660) † % Placebo (n=210) † % Anemia (<0.8 x NRL) 0.1 0 Leukopenia (<0.75 x NRL) 1.3
• 0.9 Neutropenia (<0.8 x NRL) 3.2
• 1.5 AST (SGOT) (>2 x NRH) 2.3
• 1.2 ALT (SGPT) (>2 x NRH) 3.2
• 1.5 Total Bilirubin (>1.5 x NRH) 1.9
• 1.2 Serum Creatinine (>1.5 x NRH) 0.2
• 0.3 Amylase (>1.5 x NRH) 1.5
• 1.9 Lipase (>1.5 x NRH) 4.9
• 4.7 HIV-infected patients:
• In HIV-infected patients, the most frequently reported adverse events for famciclovir (500 mg twice daily; n=150) and acyclovir (400 mg, 5x/day; n=143), respectively, were headache (17% vs. 15%), nausea (11% vs. 13%), diarrhea (7% vs. 11%), vomiting (5% vs. 4%), fatigue (4% vs. 2%), and abdominal pain (3% vs. 6%).
• 6.2 Postmarketing Experience The adverse events listed below have been reported during post-approval use of famciclovir.
• Because these events are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure:
• Blood and lymphatic system disorders:
• Thrombocytopenia Hepatobiliary disorders:
• Abnormal liver function tests, cholestatic jaundice Immune system disorders:
• Anaphylactic shock, anaphylactic reaction Nervous system disorders:
• Dizziness, somnolence, seizure Psychiatric disorders:
• Confusion (including delirium, disorientation, and confusional state occurring predominantly in the elderly), hallucinations Skin and subcutaneous tissue disorders:
• Urticaria, erythema multiforme, Stevens-Johnson syndrome, toxic epidermal necrolysis, angioedema (e.g., face, eyelid, periorbital, and pharyngeal edema), hypersensitivity vasculitis Cardiac disorders:
• Palpitations

Quoted from the official label, section “Adverse Reactions”.

What to discuss with your doctor

• Advise the patient to read the FDA-approved patient labeling (Patient Information).
• There is no evidence that famciclovir will affect the ability of a patient to drive or to use machines.
• However, patients who experience dizziness, somnolence, confusion or other central nervous system disturbances while taking famciclovir should refrain from driving or operating machinery.
• Because famciclovir contains lactose (famciclovir 125 mg, 250 mg, and 500 mg tablets contain lactose 26.8 mg, 53.6 mg and 107.2 mg, respectively), patients with rare hereditary problems of galactose intolerance, a severe lactase deficiency or glucose-galactose malabsorption should be advised to discuss with their healthcare provider before taking famciclovir.
• Herpes Labialis (Cold Sores) Patients should be advised to initiate treatment at the earliest sign or symptom of a recurrence of cold sores (e.g., tingling, itching, burning, pain, or lesion).
• Patients should be instructed that treatment for cold sores should not exceed 1 dose.
• Patients should be informed that famciclovir is not a cure for cold sores.
• Genital Herpes Patients should be informed that famciclovir is not a cure for genital herpes.
• There are no data evaluating whether famciclovir will prevent transmission of infection to others.
• Because genital herpes is a sexually transmitted disease, patients should
• avoid contact with lesions or intercourse when lesions and/or symptoms are present to
• avoid infecting partners.
• Genital herpes is frequently transmitted in the absence of symptoms through asymptomatic viral shedding.
• Therefore, patients should be counseled to use safer sex practices.
• If episodic therapy for recurrent genital herpes is indicated, patients should be advised to initiate therapy at the first sign or symptom of an episode.
• There are no data on safety or effectiveness of chronic suppressive therapy of longer than 1-year duration.
• Herpes Zoster (Shingles) There are no data on treatment initiated more than 72 hours after onset of zoster rash.
• Patients should be advised to initiate treatment as soon as possible after a diagnosis of herpes zoster.
• Denavir ® is a registered trademark of Novartis Consumer Health, Inc.
• Distributed by: Rising Pharmaceuticals, Inc.
• Saddle Brook, NJ 07663 Made in India Code: TS/DRUGS/19/1993 Revised: 07/2020

Quoted from the official label, section “Patient Counseling Information”.

Strengths and forms

• FORMS AND STRENGTHS Famciclovir tablets, USP are available in 3 strengths:
• 125 mg:
• White to pale yellow colored, round, film-coated, biconvex tablets with beveled edges, debossed with ‘X’ on one side and ‘48’ on the other side. 250 mg:
• White to pale yellow colored, round, film-coated, biconvex tablets with beveled edges, debossed with ‘X’ on one side and ‘49’ on the other side. 500 mg:
• White to pale yellow colored, oval, film-coated, biconvex tablets, debossed with ‘X’ on one side and ‘34’ on the other side.
• Tablets: 125 mg, 250 mg, 500 mg (3)

Quoted from the official label, section “Dosage Forms & Strengths”.

What it looks like and how it is packed

• Famciclovir Tablets USP, 125 mg are white to pale yellow colored, round, film-coated, biconvex tablets with beveled edges, debossed with ‘X’ on one side and ‘48’ on the other side.
• Bottles of 30 NDC 64980-349-03 Famciclovir Tablets USP, 250 mg are white to pale yellow colored, round, film-coated, biconvex tablets with beveled edges, debossed with ‘X’ on one side and ‘49’ on the other side.
• Bottles of 30 NDC 64980-350-03 Famciclovir Tablets USP, 500 mg are white to pale yellow colored, oval, film-coated, biconvex tablets, debossed with ‘X’ on one side and ‘34’ on the other side.
• Bottles of 30 NDC 64980-351-03
• Store at 20° to 25°C (68° to 77°F); excursions permitted to 15° to 30°C (59° to 86°F) [see USP Controlled Room Temperature].

Quoted from the official label, section “How Supplied”.

What is in it

• The active ingredient in famciclovir tablets, USP is famciclovir, an orally administered prodrug of the antiviral agent penciclovir.
• Chemically, famciclovir is known as 2-[2-(2-amino-9 H -purin-9-yl)ethyl]-1,3-propanediol diacetate.
• Its molecular formula is C 14 H 19 N 5 O 4 ; its molecular weight is 321.3.
• It is a synthetic acyclic guanine derivative and has the following structure Famciclovir is a white to pale yellow powder.
• It is freely soluble in acetone and methanol, and sparingly soluble in ethanol and isopropanol.
• At 25°C famciclovir is freely soluble (greater than 25% w/v) in water initially, but rapidly precipitates as the sparingly soluble (2% to 3% w/v) monohydrate.
• Famciclovir is not hygroscopic below 85% relative humidity.
• Partition coefficients are:
• octanol/water (pH 4.8) P =1.09 and octanol/phosphate buffer (pH 7.4) P =2.08.
• Famciclovir tablets, USP contain 125 mg, 250 mg, or 500 mg of famciclovir USP, together with the following inactive ingredients:
• anhydrous lactose, hydroxypropyl cellulose, hypromellose, magnesium stearate, polyethylene glycol 400, sodium starch glycolate, and titanium dioxide.
• Chemical Structure

Quoted from the official label, section “Description”.

Ingredients people check for

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Details

Source: NDC Directory · 2026-09-13 · not reviewed by a clinician

Source: US Food and Drug Administration, NDC Directory. Reuse terms: US government work (FDA).

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