Flat warts on the neck and all over the face are caused by human papilloma virus infection, and the treatment for flat warts mainly includes topical application of salicylic acid, physical therapy, surgical treatment, etc. The treatment for flat warts includes topical application of salicylic acid, physical therapy, and surgical treatment. 1. Salicylic acid: Topical salicylic acid can be used to exfoliate flat warts. Advantages of salicylic acid include that it can be self-administered, it is painless to apply, and the risk of serious side effects is very low. 2. Physical therapy: This can be done through cryotherapy, in which the low temperature generated by liquid nitrogen causes the skin lesions to become necrotic and fall off. You can also choose laser treatment, through the pulsed dye laser, high temperature to make the skin lesions necrosis and shedding. 3. Surgery: If you have a large number of flat warts on your neck and face, you need to cooperate with your doctor to choose a surgical excision to remove the warts and improve the aesthetic effect.