Flat warts are a disease caused by human papillomavirus (HPV) infection, and they are highly contagious and recurrent. Generally, they can be treated with laser therapy, but this method is mainly for patients with fewer growths. If there are many growths, the effectiveness of laser treatment may not be very good, and extensive laser use can easily cause scarring or leave laser marks. For multiple flat warts, the most common approach is still to use immunotherapy, or to take antiviral medications orally and topically over the long term. During the treatment of flat warts, it is important to avoid sharing towels or bath mitts to prevent cross-infection, although laser treatment can still be quite effective for smaller flat warts.