Pharmaceutical formulations and methods for the topical or transdermal delivery of 1isobutyl-1H-imidazo[4,5-c]-quinolin-4-amine, or 1-(2-methylpropyl)-1H-imidazo[4,5 c]quinolin-4-amine, i.e., imiquimod, to treat genital/perianal warts with shorter durations of therapy than currently prescribed for the commercially available for Aldara® 5% imiquimod cream, as now approved by the U.S. Food & Drug Administration (“FDA”), are disclosed and described. More specifically, lower dosage strength imiquimod formulations to deliver an efficacious dose of imiquimod for treating genital/perianal warts with an acceptable safety profile and dosing regimens that are shorter and more convenient for patient use than the dosing regimen currently approved by the U.S. Food & Drug Administration (“FDA”) for Aldara® 5% imiquimod cream to treat genital/perianal warts are also disclosed and described.