Penciclovir: uses, dosing, side effects & brands
Penciclovir is a herpesvirus nucleoside analog dna polymerase inhibitor sold in the U.S. under one brand, for herpes labialis and epstein-barr virus infections. Below: what the FDA label says, every product that contains it, what the pills look like, and its recall record.
Key facts
- Drug class
- Herpesvirus Nucleoside Analog Dna Polymerase Inhibitor
- Treats
- Herpes Labialis and Epstein-Barr Virus Infections
- Available as
- Topical
- Sold as
- Denavir
- Prescription?
- Prescription only
- Generic available?
- Not in our catalog
- What the pharmacy pays
- about $62 per gm — not your price
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How penciclovir is dosed
From the FDA label for Denavir (application NDA020629). Other penciclovir products — different forms, different strengths — are dosed differently. Follow the label for the one you were prescribed.
Apply DENAVIR every 2 hours during waking hours for a period of 4 days. Start treatment as early as possible (i.e., during the prodrome or when lesions appear). • Apply DENAVIR every 2 hours during waking hours for a period of 4 days ( 2 ). • Start treatment as early as possible (i.e., during the prodrome or when lesions appear). ( 2 )
Penciclovir side effects
One or more local skin reactions were reported by 3% of the subjects treated with DENAVIR and 4% of placebo-treated patients. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Mylan at 1-877-446-3679 (1-877-4-INFO-RX) or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Studies Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in clinical practice. In two double-blind, placebo-controlled trials, 1,516 patients were treated with DENAVIR (penciclovir cream) and 1,541 with placebo. One or more local adverse reactions were reported by 3% of the patients treated with DENAVIR and 4% of placebo-treated patients. The rates of reported local adverse reactions are shown in Table 1. TABLE 1 - Local Adverse Reactions Reported in Phase III Trials Penciclovir N=1,516 % Placebo N=1,541 % Application site reaction 1 2 Hypesthesia/Local anesthesia <1 <1 Taste perversion <1 <1 Rash (erythematous) <1 <1 Two studies, enrolling 108 healthy subjects, were conducted to evaluate the dermal tolerance of 5% penciclovir cream (a 5-fold higher concentration than the commercial formulation) compared to vehicle using repeated occluded patch testing methodology. The 5% penciclovir cream induced…
Who shouldn’t take penciclovir
DENAVIR is contraindicated in patients with known hypersensitivity to the product or any of its components. • Contraindicated in patients with known hypersensitivity to the product or any of its components. ( 4 )
Penciclovir drug interactions
No drug interaction studies have been performed with DENAVIR. Due to minimal systemic absorption of DENAVIR, systemic drug interactions are unlikely.
Every penciclovir product we track (1)
Same active ingredient — different manufacturer, form, price and FDA recall record. That last one is what our independent score measures.
Only one: Denavir.
How long penciclovir keeps
No penciclovir label we read sets a separate limit for after opening, but they do specify how it must be stored — and the stability behind any date assumes those conditions.
Does penciclovir expire? The in-use limits and storage rules from its labelsPenciclovir and breastfeeding
From LactMed, the US National Library of Medicine’s Drugs and Lactation Database — quoted, not rewritten.
Full LactMed record for penciclovir: levels in milk, effects in breastfed infants, and the drugs it would consider insteadAlthough there is no published experience with penciclovir during breastfeeding, infant side effects are unlikely with maternal topical application to small areas of the mother's body away from the breast. Only water-miscible cream or gel products should be applied to the breast because ointments may expose the infant to high levels of mineral paraffins via licking.
National Institute of Child Health and Human Development, record revised November 15, 2024. LactMed states its information is not a substitute for professional judgement.
What people report to the FDA about penciclovir
The FDA Adverse Event Reporting System (FAERS) collects reports from patients and clinicians. It holds 111 reports naming penciclovir, and the FDA flagged 86% of those reports as serious. The effects reported most often — leaving out reports about overdose, misuse or the condition being treated, which dominate the raw list for common medicines:
- diarrhoea16 reports
- fatigue15 reports
- headache13 reports
- cough12 reports
- hypoaesthesia11 reports
- nausea10 reports
- anaemia9 reports
- pyrexia9 reports
Read these as a signal, not a rate. A report does not mean penciclovir caused the effect — anyone can file one, and many describe people taking several medicines for several conditions. Crucially there is no denominator: FAERS does not record how many people took the drug, so these counts cannot be turned into “X% of patients” — a bigger number often just means a more widely used or more talked-about drug. Duplicates exist, and publicity drives reporting. For what is actually established, read the FDA label section above.
Source: openFDA drug/event (FAERS), retrieved July 25, 2026.
Related calculators
Frequently asked questions
What is penciclovir?
DENAVIR (penciclovir) cream 1% contains penciclovir, an antiviral agent active against herpes viruses. DENAVIR is available for topical administration as a 1% white cream. Each gram of DENAVIR contains 10 mg of penciclovir and the following inactive ingredients: cetostearyl alcohol, mineral oil, polyoxyl 20 cetostearyl ether, propylene glycol, purified water and white petrolatum.
What kind of drug is penciclovir?
The FDA classifies penciclovir as a herpesvirus nucleoside analog dna polymerase inhibitor. If you are checking whether it is safe to combine with something else, the class is what matters — two drugs from the same class usually should not be stacked.
Can you take penciclovir with other medicines?
It depends on the medicine. We check it against the FDA labels rather than guessing: our interaction checker searches each drug's own label for the other and quotes what it says, naming the section it came from. Run penciclovir against whatever else you take — and remember that a label not naming a drug is not the same as that combination being safe.
What forms does penciclovir come in?
Across the brands we track, penciclovir is currently marketed as topical, per the FDA's National Drug Code Directory. Each form is dosed differently — follow the label for the exact product you were prescribed.
Is there a generic penciclovir?
We do not currently list a generic-labelled penciclovir product. That does not always mean none exists — it means none appears under a generic name in the FDA data we track. Ask your pharmacist.
Cite this page
- APA
- pharmaranks. (2026, July 24). Penciclovir: uses, dosing, side effects & brands. https://pharmaranks.com/drugs/penciclovir
- MLA
- “Penciclovir: uses, dosing, side effects & brands.” pharmaranks, 24 July 2026, https://pharmaranks.com/drugs/penciclovir.
We summarise public FDA and NIH sources — for a clinical claim, cite the primary source we link to as well.
Sources: FDA openFDA drug label, National Drug Code Directory, and Enforcement (recall) database. This page reproduces public FDA data and is not medical advice. Dosing is set by your prescriber.
Read the full FDA label for penciclovir on DailyMed (NIH) ↗.