Evaluation of imiquimod 5% cream to modify the natural history of herpes labialis: A pilot study

Background. Imiquimod is currently approved for the treatment of genital warts and has been shown to decrease recurrences of genital herpes in the guinea pig model of genital herpes. Therefore, we evaluated the safety and potential of topical imiquimod to decrease the rate of recurrence in humans with a history of recurrent herpes labialis. Methods. Forty-seven subjects with recurrent herpes labialis applied imiquimod 5% (n = 30) or vehicle cream (n = 17) to recurrent lesion(s) on days 1, 3, and 5 of the study (day 1 of observation occurred within 48 h after recurrence of lesion). Subjects were seen at the study centers between each dose and 3 days after application of the final dose or until resolution of the lesion. Results. After application to recurrent lesions, local erythema, edema, scabbing and/or flaking, pain, burning, and maximal lesion size were significantly greater in the imiquimod group than in the vehicle group. The study was terminated early because of severe local adverse events that occurred in 5 recipients of imiquimod. The median time until the next recurrence was, however, increased from 50 days in the vehicle group to 91 days in the imiquimod group (P = .018). Conclusions. Application of imiquimod 5% cream to herpes labialis lesions was associated with a delay in the time to the first recurrence after treatment, but severe local inflammation occurred in some individuals.