In Canada, it is estimated that 75% of individuals will have at least one HPV infection (the virus that causes genital warts) in their lifetime. Genital warts most commonly occur from HPV subtypes 6 and 11 and can appear weeks or months after exposure to the virus. The highest number of new HPV infections occur before the age of 24 years in females and between 25 – 29 years among males. In 2006, 1.56 men and 1.40 women out of 1,000 had genital warts.
Genital warts can cause decreased quality of life for many people. A recent study showed that 67% of people who responded to a quality of life questionnaire felt that their social activities were affected by their genital warts, and 89% felt tense or downhearted due to their genital warts.
Genital warts can be treated with liquid nitrogen or other topical therapies, but these treatments don’t work for all people. The Gardasil vaccine is also available which protects against getting genital warts. Previous research (conducted in the Middle East) showed that taking oral zinc tablets may increase the immune response surrounding genital warts and facilitate their disappearance.
The Provincial STI clinic at the BC Centre for Disease Control (655 West 12th Avenue, Vancouver, BC) conducted a randomized controlled trial to compare the effectiveness of 100 mg of oral zinc gluconate taken twice a day against a placebo. We examined whether the group taking zinc would have a larger proportion of participants whose warts completely resolved at 8 weeks after the start of treatment. We also measured serum zinc levels before treatment in a sub-group of 34 participants.
Summary of evidence
Eighty-six patients were recruited from the BC Centre for Disease Control STI clinic. Patients received study medication for 8 weeks and returned to the clinic for each necessary standard of care treatment (every 7-10 days) until resolution of warts.
At the week 8 assessment, 15 out of 31 patients in the zinc group (48%) showed complete resolution of their warts after 8 weeks of treatment, compared to 11 of 19 (57%) patients in the placebo group (p>0.05). In addition, 30/86 participants in the zinc group experienced side effects compared to 5/86 in the placebo group. Side effects included dizziness, nausea, vomiting, and gastric pain. All of the participants who were tested for serum zinc had levels within normal limits.
Implications for practice
In our study, we were not able to demonstrate that supplementation with zinc was superior to placebo for the treatment of genital warts. This may be due to the fact that we had a large drop-out rate and were unable to enroll enough participants to have the statistical power necessary to detect a difference. The study was stopped early due to the large number of reported side effects.
In addition, none of our participants were zinc deficient and therefore it was unlikely that additional zinc would help them. We recommend that more studies be conducted on this topic, which recruit large sample sizes in zinc deficient, susceptible populations.
- The Society of Obstetricians and Gynaecologists. Incidence and prevalence of HPV in Canada. Accessed online at http://www.hpvinfo.ca/health-care-professionals/what-is-hpv/incidence-and-prevalence-of-hpv-in-canada/ on 8 Apr 2014.
- Patel H, Wagner M, Singhal P and Kothari S. Systematic review of the incidence and prevalence of genital warts. BMC Infectious Diseases. 2013;13:39.
- Marra F, Ogilvie G, Colley L, Kliewer E, Marra CA. Epidemiology and costs associated with genital warts in Canada. Sexually Transmitted Infections. 2009;85:111-115.
- Marra C, Ogilvie G, Gastonguay L, Colley L, Taylor DL, Marra F. Patients with Genital Warts Have a Decreased Quality of Life. Sexually Transmitted Infections. 2009;36(4):258-260.