Warts

Warts develop when certain types of human papillomavirus (HPV) infect cells in the outer layers of the skin. The virus can enter through tiny cuts, scratches or areas of damaged skin and causes affected cells to grow more rapidly, producing the characteristic raised or thickened area. Different HPV types tend to affect different parts of the body. Common warts frequently occur on the hands and fingers, plantar warts — often called verrucas — develop on the soles of the feet, while flat warts are usually smaller and smoother. Genital warts are caused by particular HPV types that infect the genital and surrounding skin.

HPV can spread through direct skin-to-skin contact and, in some circumstances, indirectly through contaminated surfaces. Picking, scratching or shaving over a wart can also spread the virus to nearby areas of the same person’s skin. Genital HPV types are primarily transmitted through intimate skin-to-skin sexual contact. Not everyone exposed to HPV develops visible warts because the immune system often controls the infection before noticeable growths appear. Warts may therefore develop weeks or months after exposure, making it difficult to determine exactly when transmission occurred.

The immune response plays an important role in how long warts persist. Many common skin warts eventually disappear without treatment as the immune system recognises and controls the virus, although this can take months or sometimes years. Warts may be more numerous, persistent or recurrent in people whose immune systems are weakened. Most warts are benign, but other skin conditions can sometimes resemble them. A growth that is changing rapidly, repeatedly bleeding, unusually pigmented, ulcerated or otherwise different from a typical wart should be professionally assessed rather than assumed to be viral.