Warts

For reasons that aren't entirely clear, smokers are more susceptible to infection with human papillomavirus, a large family of viruses that can cause warts including genital warts.

While genital warts are caused by sexually transmitted types of HPV, smoking is also a risk factor. Even taking the number of sex partners into account, women who smoke are nearly four times as likely to have genital warts as nonsmokers, according to one study.

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