Classifications: antiviral;
Therapeutic: antiviral

Pregnancy Category: B


10 mg/g cream


Antiviral agent active against herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2). HSV-1 and HSV-2 infected cells phosphorylate penciclovir utilizing viral thymidine kinase. Resulting form of penciclovir competes with viral DNA, thus inhibiting both viral DNA synthesis and replication.

Therapeutic Effect

Inhibits both viral DNA synthesis and replication. Effectiveness is measured in decreased viral load.


Treatment of recurrent herpes labialis (cold sores).


Hypersensitivity to penciclovir, lactation.

Cautious Use

Pregnancy (category B). Safety and efficacy in children <12 y have not been established. Safety in immunocompromised patients is not established.

Route & Dosage

Cold Sores
Adult: Topical Apply q2h while awake x 4 d


  • Apply as soon as possible after developing lesion.
  • Do not apply to mucous membranes or near the eyes.
  • Store at or below 30° C (86° F). Do not freeze.

Adverse Effects (≥1%)

CNS: Headache. Skin: Erythema.


Absorption: Minimally absorbed from cold sore.

Nursing Implications

Assessment & Drug Effects

  • Monitor the extent of lesions and treatment effectiveness.

Patient & Family Education

  • Wash hands before and after application. Avoid contact of drug with eyes.
  • Apply sunscreen to lips; may minimize recurrence of lesions.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

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