Penciclovir
Pronunciation: (pen-SYE-kloh-veer).
- Generic name
- Penciclovir
- Brand names
- Denavir, Vectavir, Fenistil Pencivir
- Drug class
- Topical antiviral (deoxynucleoside analog HSV DNA polymerase inhibitor)
Availability and supply rules vary by country
Trade names by country: United States
Australia: · Full directory
What Penciclovir is and how it works
Uses, formulations, monitoring, and supply rules can differ by patient, product, and country. Follow the exact local product information and professional advice.
Mechanism of action: how Penciclovir works
Penciclovir is a deoxynucleoside analog that inhibits herpes simplex virus (HSV-1 and HSV-2) DNA polymerase, an enzyme the virus needs to replicate its genetic material. By blocking viral DNA synthesis, penciclovir slows viral replication, which can shorten the duration of a cold sore and reduce associated pain when treatment starts early. Measurable penciclovir concentrations were not detected in the plasma or urine of healthy volunteers following single or repeated topical application of the 1% cream, even at doses approximately 67 times the estimated usual clinical dose, reflecting minimal systemic absorption. (2)
What Penciclovir is used for
Recurrent herpes labialis (cold sores) on the lips and face
FDA-approved for adults and pediatric patients 12 years of age and older. Treatment should start as early as possible — during the prodrome (tingling, redness, itching) or when a lesion first appears. (2)
Before taking Penciclovir
Do not take / not appropriate for
- "known hypersensitivity to the product or any of its components.". (Contraindication) (2)
Tell your clinician about
(2)How to take Penciclovir
- General Instructions: Wash your hands before applying. Apply a thin layer of penciclovir cream to cover the cold sore and surrounding area, then wash your hands again afterward.. Adult and Adolescent Dosing (12 years and older): Apply every 2 hours during waking hours for 4 days.. Pediatric Dosing: Safety and effectiveness in children under 12 years of age have not been established.. Administration: For external use on the lips and face only. Do not apply inside the mouth or near the eyes, as it may cause irritation; avoid use on mucous membranes, since this has not been studied.. When To Seek Review: If the cold sore does not improve, or it worsens during treatment, seek medical advice — this may be a sign of a secondary bacterial infection needing a different treatment.. Storage: Store at 20-25°C (68-77°F). Keep out of reach of children.
- This page does not provide a dose calculator. Dosing must follow the prescriber, pharmacist, or product label.
Procedures and treatment changes
Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (2)
Missed dose
If you miss an application, apply it as soon as you remember during waking hours, then continue your every-2-hour schedule for the remainder of the 4-day course. Do not apply extra cream to make up for a missed application.
Overdose
Penciclovir cream is poorly absorbed following oral ingestion, so adverse effects from accidentally swallowing a small amount are considered unlikely; the FDA label states there is no specific information available on overdose. If a large amount is swallowed, or if you are concerned, seek medical advice or contact a poison control center. (2)
Side effects
Side effects and their urgency vary; report severe, persistent, or concerning symptoms to a healthcare professional.
Local skin reactions at the application site (e.g., mild redness, stinging, or numbness)
Incidence: In two double-blind, placebo-controlled trials (1,516 patients on penciclovir cream vs. 1,541 on placebo), one or more local skin reactions were reported by 3% of penciclovir-treated patients and 4% of placebo-treated patients.
Headache
Incidence: Reported in the clinician-authored database; frequency not established
Signs of an allergic reaction (rash, swelling, difficulty breathing)
What to do: Seek immediate medical attention. (2)
A cold sore that does not improve or that worsens on treatment
What to do: Seek medical advice promptly, as this may indicate a secondary bacterial infection. (2)
Serious warnings
For external use on the lips and face only — not for use inside the mouth, in or near the eyes, or on genital herpes — serious
Symptoms: For external use on the lips and face only — not for use inside the mouth, in or near the eyes, or on genital herpes; avoid application to mucous membranes, since this has not been studied and may cause irritation.
Action: Follow the urgency stated and seek prompt or emergency care when indicated. (2)
Contraindicated in patients with known hypersensitivity to penciclovir, famciclovir (which the body converts to penciclovir), or any component of the cream — serious
Symptoms: Contraindicated in patients with known hypersensitivity to penciclovir, famciclovir (which the body converts to penciclovir), or any component of the cream.
Action: Follow the urgency stated and seek prompt or emergency care when indicated. (2)
If a cold sore does not improve, or worsens, during treatment, seek medical advice promptly — serious
Symptoms: If a cold sore does not improve, or worsens, during treatment, seek medical advice promptly; let the clinician you see assess whether a secondary bacterial infection or another condition needs different treatment.
Action: Follow the urgency stated and seek prompt or emergency care when indicated. (2)
Interactions
| Medicine or test | Effect | Action |
|---|---|---|
| Systemic drug interactions | No drug interaction studies have been performed with penciclovir cream. Because of its minimal systemic absorption when used as directed, systemic drug interactions are considered unlikely. Always tell your healthcare provider about all medicines and supplements you use. | (2) |
Pregnancy, breastfeeding, kidney/liver function, age
Pregnancy
Penciclovir cream is not absorbed into the bloodstream in measurable amounts following topical use as directed, so maternal use is not expected to expose the fetus to the drug. Discuss any pregnancy or plans for pregnancy with your prescriber. (2)
Breastfeeding
Because penciclovir cream is not absorbed systemically by the mother when used as directed, breastfeeding is not expected to expose the child to the drug. Discuss breastfeeding with your healthcare provider. (2)
Children
Frequency: Every 2 hours during waking hours for 4 days, same as adult dosing.. Weight Based: Not weight-based; fixed regimen.. Max Daily Dose: Not established as a numeric limit; follow the every-2-hour, 4-day regimen.. Max Single Dose: A thin layer covering the cold sore and surrounding area.. Age Restrictions: Approved from 12 years of age; safety and effectiveness in children under 12 have not been established. (2)
Renal_impairment
The FDA label does not include a renal- or hepatic-impairment dosing section for penciclovir cream. This is consistent with its pharmacology: in a study of healthy volunteers, no measurable penciclovir was detected in plasma or urine even after repeated dosing at about 67 times the estimated usual clinical dose, because so little of the topical cream is absorbed into the body. No dose adjustment is specified for renal or hepatic impairment; people with significant organ impairment who have other health concerns about using it should still check with their clinician or pharmacist. (2)
Hepatic_impairment
The FDA label does not include a renal- or hepatic-impairment dosing section for penciclovir cream. This is consistent with its pharmacology: in a study of healthy volunteers, no measurable penciclovir was detected in plasma or urine even after repeated dosing at about 67 times the estimated usual clinical dose, because so little of the topical cream is absorbed into the body. No dose adjustment is specified for renal or hepatic impairment; people with significant organ impairment who have other health concerns about using it should still check with their clinician or pharmacist. (2)
Monitoring
(2)Storage
Store at 20-25°C (68-77°F) (USP Controlled Room Temperature). Keep out of reach of children.
Professional information
Clinician-facing context only. This section does not replace current product labeling.
General (US FDA label)
Indication: Recurrent herpes labialis (cold sores)
Dose summary: Apply penciclovir cream 1% every 2 hours during waking hours for 4 days, in patients 12 years of age and older. Start treatment as early as possible — during the prodrome (tingling, redness, itching) or when a lesion first appears.
Renal context: The FDA label reviewed for this page states no renal-impairment guidance for penciclovir cream — there is no dedicated renal-impairment section in the label. This is consistent with the drug's pharmacokinetics: no measurable penciclovir was detected in plasma or urine of healthy volunteers even at about 67 times the usual clinical topical dose. No dose adjustment is specified; renal status should still be assessed by the prescriber if there are other health concerns. (2)
Hepatic guidance
The FDA label does not include a hepatic-impairment dosing section for penciclovir cream, consistent with its minimal systemic absorption when used topically as directed. No dose adjustment is specified.
Frequently asked questions
What is penciclovir used for?
Penciclovir cream is used to treat recurrent cold sores (herpes labialis) on the lips and face in people 12 years of age and older.
How do I use penciclovir cream?
Apply a thin layer to the cold sore and surrounding skin every 2 hours during waking hours for 4 days, starting as early as possible — ideally at the first tingling, redness, or itching, before the sore fully appears. Wash your hands before and after applying.
Can I use penciclovir inside my mouth or near my eyes?
No. Penciclovir cream is for use on the lips and face only. Avoid application inside the mouth, in or near the eyes, or on mucous membranes, as this has not been studied and may cause irritation.
What are the most common side effects of penciclovir?
Local skin reactions at the application site are the most commonly reported effect, occurring at about the same rate as with placebo cream in clinical trials (3% vs. 4%). Headache has also been reported.
Is penciclovir cream safe during pregnancy or breastfeeding?
Penciclovir cream is not absorbed into the bloodstream in measurable amounts when used as directed, so it is not expected to expose a fetus or breastfed infant to the drug. Even so, discuss your individual situation with your healthcare provider before use.
Can children use penciclovir cream?
Penciclovir cream is approved for cold sores in people 12 years of age and older. Safety and effectiveness in children under 12 have not been established.
What should I do if my cold sore doesn't improve?
If the cold sore does not improve, or it worsens while you are using penciclovir, seek medical advice promptly — this could be a sign of a secondary bacterial infection that needs different treatment.
What happens if penciclovir cream is accidentally swallowed?
Penciclovir is poorly absorbed after oral ingestion, so adverse effects from accidentally swallowing a small amount are considered unlikely, and the FDA label states there is no specific information on overdose. If a larger amount is swallowed or you are concerned, seek medical advice or contact a poison control center.
Does penciclovir interact with other medicines?
No drug interaction studies have been done with penciclovir cream, but because so little is absorbed into the bloodstream when used as directed, systemic drug interactions are considered unlikely. Tell your healthcare provider about all medicines and supplements you use.
What is the mechanism of action of Penciclovir?
Penciclovir is a deoxynucleoside analog that inhibits herpes simplex virus (HSV-1 and HSV-2) DNA polymerase, an enzyme the virus needs to replicate its genetic material. By blocking viral DNA synthesis, penciclovir slows viral replication, which can shorten the duration of a cold sore and reduce associated pain when treatment starts early. Measurable penciclovir concentrations were not detected in the plasma or urine of healthy volunteers following single or repeated topical application of the 1% cream, even at doses approximately 67 times the estimated usual clinical dose, reflecting minimal systemic absorption. (2)
What is the generic name of Penciclovir?
The generic name is Penciclovir. It is sold under brand names including Denavir, Vectavir, Fenistil Pencivir.
What class of drug is Penciclovir?
Penciclovir is classed as: Topical antiviral (deoxynucleoside analog HSV DNA polymerase inhibitor).
References
- Clinician-authored medicine record for PenciclovirMedGuideGlobal · Global (internal) · accessed 2026-08-07 · source 1
- DENAVIR (penciclovir) cream 1% — FDA-approved prescribing information (Mylan Pharmaceuticals)U.S. FDA (via DailyMed) · United States · accessed 2026-08-07 · source 2
- PENCICLOVIR CREAM [TORRENT PHARMACEUTICALS LIMITED] — US prescribing information (DailyMed SPL)U.S. National Library of Medicine (DailyMed) · US · accessed 2026-08-14 · source 3
- Penciclovir Cream — patient drug information (MedlinePlus)U.S. National Library of Medicine (MedlinePlus) · US · accessed 2026-08-14 · source 4
- Penciclovir — FDA approval record (Drugs@FDA ANDA212710)U.S. Food and Drug Administration · US · accessed 2026-08-14 · source 5
- Penciclovir — RxNorm normalized drug concept (RXCUI 59839)U.S. National Library of Medicine (RxNorm) · US · accessed 2026-08-14 · source 6
Brand names by country
Single-ingredient Penciclovir names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.
Priority countries
United States
- Denavir10 mg/g · mylan pharmaceuticals inc.