FDA-filed SPL labeling · retrieved through openFDA

Famciclovir

Famciclovir is an antiviral tablet used to treat and suppress cold sores, genital herpes, and shingles in adults.

Brand name Famvir
Drug class ⓘ Herpes Simplex Virus Nucleoside Analog Dna Polymerase Inhibitor
Rx Form 1 Route Oral
Dr. Brian Staiger, PharmD, BCPS
Reviewed by Last reviewed Jul 10, 2026
🧬 Where this information comes from Click to expand

The clinical label records used on this page are FDA-filed Structured Product Labeling (SPL) retrieved through openFDA. We identified 14 clinical label sets within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. Forms, routes, brands, labelers, strengths, and NDC product-record counts are built separately from matching FDA National Drug Code Directory records. The linked DailyMed document is a representative official source for verification, not the page’s only clinical source. View the linked label on DailyMed →

At a glance
Linked label effectiveJan 14, 2026
Clinical labels in scope ⓘ14
AvailabilityRx
Earliest approval/marketing year ⓘ1994
FDA-listed product records ⓘ84
Boxed warningNone found in compared labels
How we combine label and product data →
✓No current FDA shortage listed · checked Sep 22, 2026 🚨Recall on record
⭐ Famciclovir at a glance The quick version — the full detail is in the Patient Information Guide below.
💊
HelloPharmacist Editorial Team Bottom Line
Famciclovir is an effective antiviral for treating cold sores, genital herpes outbreaks, and shingles in adults, and can also be taken daily to suppress recurring genital herpes. It works best when started at the very first sign of an outbreak, so don't wait. If you have kidney disease, make sure your prescriber knows — your dose must be tailored to your kidney function to avoid serious side effects.
How we write & review this content — our editorial policy →

📖 Famciclovir: Patient Information Guide

A plain-language walkthrough of Famciclovir — what it treats, how it works, how it’s taken, side effects, warnings and interactions. Tap any section to expand it.

🎯What it's used for▾

Famciclovir tablets are an antiviral medication approved for several herpes virus infections in adults. Here are the supported uses:

  • Cold sores (herpes labialis): Treatment of recurrent cold sores in immunocompetent (normal immune system) adults
  • Genital herpes – treatment: Treatment of recurrent genital herpes episodes in immunocompetent adults
  • Genital herpes – suppression: Daily suppressive therapy to reduce recurrent genital herpes episodes in immunocompetent adults (safety and efficacy beyond 1 year has not been established)
  • Shingles (herpes zoster): Treatment of shingles in immunocompetent adults
  • Recurrent orolabial or genital herpes in HIV-infected adults: Treatment of recurrent episodes of cold sores or genital herpes in adults living with HIV
  • Not approved for: First episode of genital herpes, eye-area shingles (ophthalmic zoster), children, or immunocompromised patients other than HIV-infected adults with recurrent orolabial or genital herpes
⚙️How it works▾

Famciclovir is a prodrug — it isn't active on its own. After you swallow it, your body rapidly converts it into penciclovir, the active antiviral compound. Penciclovir works by blocking a viral enzyme called DNA polymerase, which the herpes virus needs to replicate (make copies of) itself. By shutting down this enzyme, penciclovir stops the virus from spreading, which shortens the outbreak and eases symptoms.

Famciclovir does not cure herpes — the virus stays in the body — but it significantly reduces the severity and duration of outbreaks when taken early. It does not appear to be processed through the main liver enzyme pathway (CYP450), which limits certain drug interactions.

💊How it's taken▾

Famciclovir tablets are taken by mouth and can be swallowed with or without food — food slows the rate of absorption slightly but does not reduce the total amount that gets into your system. Depending on what it is being used for, it may be taken as a single one-time dose, twice a day for one or several days, or up to three times daily for a week. For daily suppressive therapy of genital herpes, it is taken twice a day on an ongoing basis.

  • Start treatment at the very first sign of a cold sore or genital herpes outbreak for the best chance of benefit
  • For shingles, begin as soon as possible after diagnosis — ideally within 72 hours of rash onset
  • If you have reduced kidney function, your prescriber will adjust your dose accordingly — do not adjust it on your own
  • Follow your prescriber's instructions exactly; do not stop or change your dose without talking to them first
🤒Side effects — in detail▾

The most commonly reported side effects with famciclovir include:

  • Headache
  • Nausea
  • Diarrhea
  • Fatigue
  • Vomiting
  • Gas (flatulence)
  • Itching (pruritus)
  • Abdominal pain

More serious reactions — though rare — include severe allergic reactions (anaphylaxis), sudden kidney injury, low platelet counts (thrombocytopenia), liver problems, confusion or hallucinations (especially in older adults), seizures, and severe skin reactions like Stevens-Johnson syndrome. Get medical help right away if you experience any of these.

⚠️Warnings & precautions▾
  • Acute kidney injury: Serious, sudden kidney damage has occurred in people with pre-existing kidney disease who received doses that were too high for their level of kidney function. Dose adjustment is required in kidney impairment — this is critical.
  • Severe skin reactions: Rare but life-threatening skin conditions including Stevens-Johnson syndrome and toxic epidermal necrolysis (widespread skin blistering and peeling) have been reported. Seek emergency care immediately if you develop a severe or spreading rash with blistering or skin peeling.
  • Serious allergic reactions: Anaphylaxis (a severe, whole-body allergic reaction with throat swelling or difficulty breathing) has been reported. Stop the medication and get emergency help if this occurs.
  • Neurological effects: Confusion, disorientation, hallucinations, and seizures have been reported — more commonly in elderly patients.
  • Low platelet counts (thrombocytopenia): Reported post-marketing; watch for unusual bruising or bleeding.
🔀What it interacts with▾

Famciclovir has a relatively limited interaction profile, but a few combinations are worth knowing about:

  • Probenecid (gout medication): Can raise penciclovir blood levels, potentially increasing side effects — your doctor may monitor you more closely
  • Other drugs eliminated by kidney secretion: May also raise penciclovir levels and could increase the risk of side effects
  • Raloxifene (osteoporosis/breast cancer prevention): A potent inhibitor of the enzyme that activates famciclovir in the lab — though no clinical study has confirmed the magnitude of this interaction, tell your doctor if you take raloxifene
  • Digoxin, zidovudine, emtricitabine, allopurinol, theophylline, antacids: No clinically significant interactions were found in studies with these drugs

This is not a complete list of interactions. Always talk with your doctor or pharmacist before starting, stopping, or changing any medication.

📋Before taking it▾
  • Kidney disease: Dose must be adjusted based on your creatinine clearance (a measure of kidney function) — taking the standard dose with impaired kidneys can cause serious harm
  • Allergy to famciclovir or penciclovir: Do not take famciclovir if you are allergic to this medication or to Denavir (penciclovir cream)
  • Pregnancy: Animal studies showed no harm to the fetus, and available human data have not identified a clear drug-related risk — but discuss the benefits and risks with your doctor, since untreated herpes in pregnancy also carries risks to the baby
  • Breastfeeding: It is unknown whether penciclovir passes into human breast milk — discuss with your doctor before breastfeeding while taking this medication
  • Children: Famciclovir has not been proven effective in children and is not recommended in pediatric patients or infants
  • Older adults: No significant difference in side effect rates was seen in older patients in clinical trials, but kidney function often declines with age, so dose adjustment may be needed
  • Conditions not covered: Famciclovir is not approved for a first episode of genital herpes, shingles affecting the eye, or for immunocompromised patients other than HIV-infected adults with recurrent orolabial or genital herpes
🚑If you take too much▾

If too much famciclovir is taken, treatment is supportive — meaning doctors will treat the symptoms. There is no specific antidote. Penciclovir, the active form of the drug, can be removed from the body by hemodialysis (kidney dialysis). If you suspect an overdose, contact a poison control center or seek emergency medical care right away.

🔬Pharmacokinetics — how your body processes it▾

After you swallow famciclovir, your body rapidly converts it into its active form, penciclovir — very little famciclovir itself is ever detected in your blood or urine. About 77% of the penciclovir from an oral dose actually reaches your bloodstream (this is called bioavailability), and peak levels are reached in under an hour. Penciclovir is not heavily bound to proteins in the blood and spreads well into body tissues.

Penciclovir is cleared mainly by the kidneys, largely unchanged. Because of this, kidney function directly affects how much of the drug stays in your system — people with kidney disease need lower doses to avoid buildup. The drug can be taken with or without food; while food slows how fast penciclovir peaks in the blood, it does not change the total amount absorbed.

📦How to store it▾

Store at 20° to 25°C (68° to 77°F) .

📄 Written from Famciclovir’s FDA-approved label information, summarized in plain language with AI, and reviewed by our pharmacy team before publication. Every point is grounded in that labeling — nothing is invented. How we use AI →

17

Supplements & herbs that interact with Famciclovir

17 supplements and herbal products have documented interactions with Famciclovir in the licensed clinical database we use. Most are manageable — but your pharmacist should know about everything you take, including vitamins and herbals.

Severity mix
  • Major · 1
  • Moderate · 7
  • Minor · 9
ACTIVATED CHARCOAL Major COFFEE CHARCOAL Moderate EUROPEAN MANDRAKE Moderate GLUCOMANNAN Moderate GUAR GUM Moderate GUM ARABIC Moderate SLIPPERY ELM Moderate TRAGACANTH Moderate +9 more
Every supplement checked against Famciclovir — ranked by severity The full interaction hub: 1 major · 7 moderate · 9 minor · every one linked to its full report. Check Famciclovir against your exact supplements

Educational information from a licensed clinical database (Natural Medicines) — see our data sources & update cadence. Not medical advice: an interaction being documented does not mean it will happen to you; do not start or stop medications or supplements without professional guidance.

🩺 Pharmacist Counseling Corner

Quick, plain-English answers to the questions patients ask most about Famciclovir — the kind of thing our pharmacy team would talk through with you at the counter.

What exactly is famciclovir used for? ▾
Famciclovir is an antiviral medication used to treat herpes virus infections in adults. It can treat cold sores, recurring genital herpes outbreaks, and shingles. If you get genital herpes outbreaks frequently, it can also be taken every day to suppress them and reduce how often they happen. For adults living with HIV, it's used to treat recurring cold sores or genital herpes outbreaks. It doesn't cure herpes — the virus stays in your body — but it helps outbreaks heal faster and feel less severe.
When should I take it — do I need to start right away when I feel an outbreak coming on? ▾
Yes, timing really matters. For cold sores and genital herpes, famciclovir works best when you start it at the very first hint of an outbreak — that tingling, itching, or burning feeling before a sore even appears. For shingles, you should start it as soon as your doctor confirms the diagnosis, ideally within 72 hours of the rash showing up. If you wait too long, the medication may be less effective. Keep your prescription on hand so you're ready to start quickly.
Can I take famciclovir with food, and are there any foods or drinks I need to avoid? ▾
You can take famciclovir with or without food — it doesn't matter. Food can slow down how quickly the drug kicks in, but it doesn't reduce how much of it your body absorbs overall. There are no specific foods you need to avoid. Just take it in a way that's easy for you to remember and be consistent.
What side effects should I watch out for? ▾
The most common side effects are headache and nausea — these are generally mild. You might also notice diarrhea, fatigue, or an upset stomach. More serious but rare reactions include severe skin blistering or peeling, signs of a bad allergic reaction (like throat swelling or trouble breathing), confusion or hallucinations (especially in older adults), unusual bruising or bleeding, or signs that your kidneys are struggling (like much less urine than usual). If any of those more serious things happen, stop the medication and get medical help right away.
I have kidney problems — is famciclovir safe for me? ▾
You can still use famciclovir, but your dose will need to be adjusted based on how well your kidneys are working. This is really important — taking a standard dose when your kidneys aren't functioning at full capacity can cause serious kidney damage. Make sure your prescriber knows about your kidney condition before you start, and follow their dosing instructions exactly. Don't adjust the dose on your own.
Is famciclovir safe during pregnancy or while breastfeeding? ▾
Animal studies didn't show harm to developing babies, and the available data from human pregnancies haven't raised clear red flags. But there's not a huge amount of data, and untreated herpes during pregnancy carries its own risks to the baby. If you're pregnant or planning to become pregnant, have an honest conversation with your doctor so you can weigh the benefits and risks together. As for breastfeeding, it's not yet known whether the active drug passes into human breast milk, so check with your doctor before breastfeeding while taking famciclovir.
Is Famciclovir available over the counter? ▾
Famciclovir is dispensed by prescription according to its FDA labeling, so it isn't sold over the counter. Your prescriber and pharmacist will determine if it's appropriate for you.
When was Famciclovir first available? ▾
Famciclovir has been available in the United States since at least 1994, based on FDA approval history (Drugs@FDA) and product marketing records.
Who makes Famciclovir? ▾
Famciclovir is supplied by 21 manufacturers listed in the FDA NDC Directory, including AvKARE, Aurobindo Pharma Limited, Teva Pharmaceuticals USA, Inc..

💬 Answers drafted from Famciclovir’s FDA-approved label information, summarized in plain language with AI, and reviewed by our pharmacy team before publication. Grounded in that labeling — nothing is made up. How we use AI →

🧰 Keep exploring

📊Famciclovir supplement interactions17 checked — ranked by severity 🌿Drug & Supplement CheckerFamciclovir vs. vitamins & herbs 💬Ask a PharmacistFree answer, usually < 24h 🔎NDC & pricing lookupFind Famciclovir NDCs & costs 🅰️Browse Drugs A–ZLook up any medication

💊 How Famciclovir comes

Famciclovir is available in 1 form. Different forms and brands can have different approved uses, doses, schedules, and directions. Follow the instructions for your exact product, and do not switch forms without guidance from your prescriber or pharmacist.

Tablet

By mouth
How this form is used
What it may be used for
  • Famciclovir tablet is used to treat recurrent cold sores (herpes labialis) in immunocompetent adults
  • Famciclovir tablet is used to treat recurrent genital herpes episodes and as daily suppressive therapy in immunocompetent adults
  • Famciclovir tablet is used to treat shingles (herpes zoster) in immunocompetent adults
  • Famciclovir tablet is used to treat recurrent orolabial or genital herpes in HIV-infected adults
Important instructions
  • Famciclovir tablets may be taken with or without food
  • Famciclovir tablets should be started at the first sign or symptom of a cold sore or genital herpes outbreak (such as tingling, itching, or burning) for best effect
  • For shingles, Famciclovir tablets should be started as soon as the diagnosis is made — ideally within 72 hours of rash onset
  • For HIV-infected patients with recurrent herpes, Famciclovir tablets are most effective when started within 48 hours of symptom or lesion onset
Available strengths 3 strengths
125 mg 250 mg 500 mg
76 FDA-listed product records ⓘ

📊 Famciclovir across the U.S. market

How Famciclovir appears in the FDA’s National Drug Code Directory — including its dosage forms, strengths, brand names, manufacturers, and FDA-listed product records. These are directory records, not sales or prescription volume.

1
Dose forms ⓘ
21
Manufacturers
1
Brand names
84
FDA-listed product records ⓘ
1994
First marketed ⓘ

Also listed with the FDA, not a patient dose form: Powder (8) — bulk drug substance sold to compounders/manufacturers and multi-item kits. These aren’t counted in the dose-form total above.

AvKARE14%
Aurobindo Pharma Limited12%
Teva Pharmaceuticals USA, Inc.11%
Macleods Pharmaceuticals Limited11%
Apotex Corp.8%
Camber Pharmaceuticals, Inc.7%
Other makers37%

Share of FDA-listed product records by manufacturer — FDA National Drug Code Directory. Record counts are not sales or prescription volume.

📈 How widely Famciclovir is used

A general measure of how commonly Famciclovir is prescribed, based on Medicaid — one of the largest public drug programs. The figure below is prescriptions filled in Q1–Q4 2025, summed across every form and brand of the drug.

Think of this as a proxy for how widely Famciclovir is used, drawn from freely available public data. Medicaid is just one program — these numbers don’t include Medicare, other government coverage, or commercial and cash-pay prescriptions, so real-world use is higher than what’s shown here.

11,935
Medicaid prescriptions filled (Q1–Q4 2025)
$420,235 gross Medicaid reimbursement (before mandatory rebates — net cost is lower)

How commonly is Famciclovir prescribed? Of the 1,596 medications we measure, Famciclovir ranks #897 by Medicaid prescriptions — more than 44% of them.

Where Famciclovir ranks among the drugs we measure · Q1–Q4 2025 · neighbors ±5
Total prescriptions — #897 of 1,596
#892 Sertaconazole Topical 12,283 Rx #893 Glatiramer Injection 12,218 Rx #894 Phytonadione 12,205 Rx #895 Nitroglycerin Transder... 12,007 Rx #896 Everolimus 11,955 Rx #897 Famciclovir 11,935 Rx #898 Cyclophosphamide Injec... 11,741 Rx #899 Dasatinib 11,700 Rx #900 Nateglinide 11,692 Rx #901 Doravirine 11,622 Rx #902 Sulfacetamide Ophthalm... 11,572 Rx

Utilization by Famciclovir product

Pick a product to see its own Medicaid numbers. Each chip is one clinical product — a specific strength & dosage form as defined by RxNorm — with brand-name and generic versions combined.

The 500 mg oral tablet is the most-dispensed Famciclovir product — about 77% of these Medicaid prescriptions.

famciclovir 500 MG Oral Tablet Most dispensed

9,238 Medicaid prescriptions (Q1–Q4 2025) 77% of Famciclovir prescriptions shown $323,816 gross reimbursement (before rebates) ≈ $35 per prescription (gross)

Summed across the 5 of 38 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 198382

famciclovir 250 MG Oral Tablet

2,660 Medicaid prescriptions (Q1–Q4 2025) 22% of Famciclovir prescriptions shown $95,500 gross reimbursement (before rebates) ≈ $36 per prescription (gross)

Summed across the 3 of 24 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 199193

famciclovir 125 MG Oral Tablet

37 Medicaid prescriptions (Q1–Q4 2025) <1% of Famciclovir prescriptions shown $919 gross reimbursement (before rebates) ≈ $25 per prescription (gross)

Summed across the 2 of 18 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 199192

Shares are of the Medicaid prescriptions shown here. Product grouping follows RxNorm (the National Library of Medicine’s drug terminology), so “one product” means one strength & dosage form regardless of manufacturer. Dollar figures are gross Medicaid reimbursement before mandatory rebates — rebates (often large, especially for brand-name drugs) are confidential, so actual net cost to Medicaid is lower than shown.

Source: Medicaid State Drug Utilization Data (CMS), aggregated by generic ingredient — summed across every NDC (all brands, strengths, salt forms and dosage forms) of Famciclovir, and across all states and both fee-for-service and managed-care claims. A general popularity signal; it excludes Medicare, commercial insurance and cash prescriptions, so it is not total U.S. use. Based on the 10 of 80 listed Famciclovir NDCs with Medicaid activity.

🔍 Compare Famciclovir products

A representative set of FDA-listed product records for Famciclovir — across manufacturers, strengths, and dosage forms, grouped by form with each product’s manufacturer and how the FDA approved it. The same medicine may be made and packaged by different companies, so a single drug can have many directory entries. (It’s also why a refill can look different — a new shape, color, or box — even though it contains the same medication.)

Showing 84 of 84 products — FDA National Drug Code Directory. See every product, package size and price: browse all 84 Famciclovir NDCs →

RxNorm Concept Web — From Ingredient to Every Form and Strength

This page starts with one ingredient concept (IN). The branches below show its dose-form concepts (SCDF), then the available clinical drug and strength concepts (SCD). Combination products remain separate concepts with their own pages.

Ingredient (IN) Famciclovir RxCUI 68099 1 dose form · 4 strengths
  1. Dose form (SCDF) Oral Tablet RxCUI 372137 In current FDA listings
    Clinical drug / strength (SCD) 125 MG RxCUI 199192 250 MG RxCUI 199193 500 MG RxCUI 198382 750 MG RxCUI 152981

Look up RxCUI 68099 in the RxCUI Atlas →

RxNorm is the U.S. National Library of Medicine’s normalized drug vocabulary. Its concept hierarchy can include forms that are not currently marketed; the status on each branch compares that concept with current FDA listings. RxCUIs identify vocabulary concepts, not individual packages or manufacturers.

🏷️ Sold under these brand names

Famvir

🏭 Manufacturers & labelers

AvKARE 12 Aurobindo Pharma Limited 10 Teva Pharmaceuticals USA, Inc. 9 Macleods Pharmaceuticals Limited 9 Apotex Corp. 7 Camber Pharmaceuticals, Inc. 6 Proficient Rx LP 5 Atlantic Biologicals Corp. 3 Rising Pharmaceuticals, Inc. 3 Rising Pharma Holdings, Inc. 3 PD-Rx Pharmaceuticals, Inc. 3 Golden State Medical Supply, Inc. 3 Bryant Ranch Prepack 3 Hetero Drugs Limited 1 Professional Compounding Centers Of America 1 Darmerica, LLC 1 Cipla Ltd. 1 RPK Pharmaceuticals, Inc. 1 Shanghai Pharma Group Changzhou Kony Pharmaceutical Co., Ltd. 1 Signa S.A. de C.V. 1 AX Pharmaceutical Corp 1

RxNorm drug class

Famciclovir belongs to the Herpes Simplex Virus Nucleoside Analog DNA Polymerase Inhibitor class.

Pharmacologic class Herpes Simplex Virus Nucleoside Analog DNA Polymerase Inhibitor
Drug family (ATC) Nucleosides and nucleotides excl. reverse transcriptase inhibitors, Antivirals
How it works DNA Polymerase Inhibitors

Classified by RxNorm RxClass — the U.S. National Library of Medicine's standardized drug-classification service (Established Pharmacologic Class from the FDA, the ATC drug family from the WHO, and mechanism of action). Reference only, not medical advice.

🔬 Where this comes from

Core label, product, RxNorm, safety, and utilization data on this page come from the sources identified below. AI-written, editorial, and licensed sections are labeled separately.

📄
FDA-filed drug labels (SPL) Uses, dosing, warnings & side effects from SPL records retrieved through openFDA; the linked representative set can be verified on DailyMed. ✓ Linked label effective Jan 14, 2026
🏭
Forms, brands & labelersAggregated from ingredient-matched FDA National Drug Code Directory product records for Famciclovir.
📈
Real-world reportsThe FDA Adverse Event Reporting System (FAERS), served through openFDA.
🚨
Recalls & shortagesopenFDA drug-enforcement reports and the FDA drug-shortage database.
🧾 Clinical label set — FDA-filed SPL labels retained for Famciclovir after exact ingredient or ingredient-combination matching and applicable route/form matching
Clinical labels in scope
14
NDC products indexed
84
Distinct labelers/manufacturers represented
21
Linked representative label ⓘ
AvKARE
Linked label effective
Jan 14, 2026
Composite sections available
21
Linked SPL Set ID
c2b21ad5-fa83-1fb6-e053-2a95a90a3d0f
Linked SPL Document ID
485cfe40-2ff0-e83f-e063-6394a90a221c
Open the linked representative label on DailyMed ↗

How we combine label and product data

HelloPharmacist combines public FDA and NLM records; we don’t author the underlying clinical facts. We identified 14 FDA-filed SPL label sets within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. The representative label is the starting point for the displayed reference monograph; the 12 largest stored in-scope SPL records, which may include that representative, are compared section by section, and the longest available version of each section is retained. Forms, routes, brands, labelers, product-listed strengths, and product-record counts are aggregated separately from ingredient-matched FDA NDC Directory records; package records listed above are associated with the linked SPL; and the normalized concept hierarchy comes from NLM RxNorm.

For canonical ingredient pages, bounded product-attributed indication and administration excerpts may be added to the AI evidence, and the generator is instructed to preserve available product, brand, route, and form qualifiers instead of treating one label as universal. Where a section is identified as AI-written, its plain-language text is generated from bounded label evidence. New draft drug pages remain in the admin review queue before first publication. AvKARE is the representative DailyMed label linked for verification and dates; it is not the sole source used for the page.

This is general education, not medical advice — always consult your doctor or pharmacist about your medications and any medical condition. For the exact wording of the linked representative label, view that label on DailyMed; some displayed composite sections may come from other in-scope SPL labels. Learn how we use AI and our data sources & update cadence.