Table 7-Trials involving intralesional and intramuscular interferon treatment of genital warts


Treatment/trial type

Patient number

Immediate response during treatment

Recurrence or study conclusion data


Interferon (1 X 106 international units (IU)) directly into one to three warts three times weekly for three weeks versus placebo

257 patients

At one week after the completion of therapy, interferon had produced a large and significantly greater reduction in mean wart area (a 62.4 percent decrease), as compared with placebo (a 1.2 percent increase in mean area) (P less than 0.001).

At the conclusion of the study (13 weeks after the completion of therapy), the mean wart area was still decreased 39.9 percent below the initial size in the interferon group, whereas it had increased by 46 percent over base-line measurements in the placebo group (P less than 0.001). At the same time, all treated warts had completely cleared in 36 percent of the interferon recipients and in 17 percent of the placebo recipients (P less than 0.001), whereas treated warts progressed in 13 percent of the interferon recipients and in 50 percent of the placebo recipients (P less than 0.001)


1 x 106 units of interferon or placebo injected three times per week for 4 weeks with either.


Forty-seven percent of warts injected with interferon resolved completely, compared with 22% of placebo-injected warts (P = 0.009).

Approximately one third of interferon-injected warts recurred, compared with none of four placebo-injected warts.


51 were treated intramuscularly (IM) with 3 x 106 U (3 MU)/m2 daily for 3 weeks (total dose 63 MU/m2), 50 received subcutaneous thrice-weekly injections of 3 MU/m2 for 4 weeks (total dose 36 MU/m2), 51 underwent diathermocoagulation, and 48 were not treated and were used as a control group


. Six months after the end of treatment, the overall response rate (complete and partial responses) was 70%: 57 and 82% for patients receiving interferon alpha-2b (IM and subcutaneously) and diathermocoagulation, respectively, and 8% for the control group. After 6 months from therapy, no significant differences in complete response were found among the different types of treatment: 20, 20, and 35% for the two interferon groups and the diathermocoagulation group, respectively.

Fifteen and two complete responders in the cauterization and interferon groups, respectively, experienced disease recurrence (P less than .01).


patients were randomized to receive either one million international units (IU) of r-hIFN-β-1a or placebo intralesionally into each lesion, 3 times a week, for a total of 9 occasions.

60 patients with up to 8 distinct genital warts. 

The complete response rate was not significantly better with r-hIFN-beta-1a than with placebo.

However, after 3 months, 73.3% of patients treated with r-hIFN-beta-1a had experienced at least a partial response to treatment, compared with 33.3% of placebo-treated patients. At 19 days and 6 weeks, r-hIFN-beta-1a produced a significantly larger reduction in the area of genital warts. Lesions with detectable HPV6 or 11 showed a trend towards a better response rate to treatment with r-hIFN-beta-1a than lesions where no HPV DNA was detected.