Flat warts are caused by human papillomavirus infection, there are more treatment options, topical retinoic acid ointment can treat flat warts. The cause of flat warts is clear, it is caused by human papilloma virus infection. Vitamin A ointment can induce epidermal hyperplasia, differentiation, keratolysis, and can be used to treat flat warts. Topical application of this product may cause skin irritation such as burning sensation, erythema and flaking, and is contraindicated in women during the first 3 months of pregnancy. It is contraindicated in patients with acute or subacute dermatitis, eczema-like skin diseases. In addition, flat warts can also be treated by physical therapy, such as laser, liquid nitrogen freezing. The laser can be used to cauterize and destroy the warts, and liquid nitrogen freezing can be used to make the warts necrotic and fall off. The actual dermatologist will be able to help you with the treatment of your warts, as well as the specific medication you need to use.