Use this medication at the first sign of infection (such as tingling, burning, redness, or sores). Wash your hands with soap and water before and after applying this medication. Clean and dry the affected areas before applying the medication. Apply a thin layer of penciclovir cream to completely cover the area of the cold sore or the area of tingling/itching/redness/swelling, and rub in gently. Apply the cream as directed by your doctor, usually every 2 hours (except during sleep) for 4 days.

Apply to skin only. Do not apply this medication in or near the eyes since this medication can irritate the eyes. If you do get medication in your eyes, flush with plenty of water. Do not apply inside the mouth or nose.

Dosage is based on your medical condition and response to treatment. Do not use this drug more often or for longer than prescribed.

Use this medication regularly to get the most benefit from it. This medication works best when the amount of drug absorbed by the skin stays at a constant level. Use this drug at evenly spaced intervals. To help you remember, use it at the same times each day.

Cold sores (herpes) can spread easily. Penciclovir cream does not prevent the spread of herpes. Avoid close physical contact with others (such as kissing) during an outbreak until the cold sores have completely healed. Also, try not to touch the cold sore, and wash your hands if you do touch the cold sore.

Tell your doctor if your condition lasts or gets worse after treatment is finished.