Imiquimod 5% cream for the treatment of actinic keratosis: results from a phase III, randomized, double-blind, vehicle-controlled, clinical trial with histology

J Am Acad Dermatol. 2004 Oct;51(4):547-55. doi: 10.1016/j.jaad.2004.02.022.


Background: Increasing evidence suggests imiquimod may be a safe therapeutic option for the treatment of actinic keratosis (AK). The diagnosis and assessment of most AK lesions is made clinically, without histologic confirmation.

Objective: A phase III, randomized, double-blind, parallel group, vehicle-controlled study evaluated the efficacy of imiquimod 5% cream compared with vehicle in the treatment of AK lesions on the face and balding scalp including pretreatment and posttreatment biopsy specimens.

Methods: A total of 286 patients at 18 centers in 6 European countries with histologically confirmed AK were randomized to either imiquimod 5% cream or vehicle cream. Study cream was applied once per day, 3 days per week, for 16 weeks. Clearance of AK lesions was clinically and histologically assessed at an 8-week posttreatment visit.

Results: The complete clearance rate for the imiquimod group was 57.1% versus 2.2% for the vehicle group (P <.001). The partial clearance rate (> or =75% reduction in baseline lesions) for the imiquimod group was 72.1% versus 4.3% for the vehicle group (P <.001). The most common side effects were erythema, scabbing/crusting, and erosions/ulceration. For the imiquimod group the incidence of severe erythema, scabbing/crusting, or erosions/ulceration was 30.6%, 29.9%, and 10.2%, respectively.

Conclusion: Imiquimod 5% cream used 3 times per week for 16 weeks is an effective treatment for AK. Clinical clearance was established by both clinical observation and histologic analysis.

Publication types

  • Clinical Trial
  • Clinical Trial, Phase III
  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Aminoquinolines / pharmacokinetics
  • Aminoquinolines / therapeutic use*
  • Confidence Intervals
  • Double-Blind Method
  • Female
  • Humans
  • Imiquimod
  • Keratosis / complications
  • Keratosis / drug therapy*
  • Male
  • Photosensitivity Disorders / complications
  • Photosensitivity Disorders / drug therapy*


  • Aminoquinolines
  • Imiquimod