1.The working principle of carbon dioxide laser The laser beam is output by the focusing mirror, and the high temperature generated by the focus can vaporize the target tissue, which can be used for cutting, burning and coagulation surgery. 2, carbon dioxide laser in the dermatology indications filiform warts, common warts, flat warts, condyloma, molluscum contagiosum, sweat duct tumor, seborrheic keratosis (age spots), pigmented nevus (less than 5 mm), lid xanthoma, spider nevus, etc. 3.Before carbon dioxide laser treatment: Carbon dioxide laser treatment uses the instant high temperature of carbon dioxide laser to remove the lesions on the skin, the skin will be traumatized, and the traumas may be deep or shallow or have secondary infection, which may leave pigmentation or scars after healing. (1) people with hemophilia or low platelets and bleeding tendency; (2) people with keloid; (3) people with epilepsy and mental illness; (4) people with previous allergy to anesthetic drugs. 4, carbon dioxide laser postoperative precautions (1) keep the trauma clean, dry, 3-7 days to avoid water. The surrounding skin can be cleaned with wet towels. (2) After the treatment of the wound according to the doctor’s instructions to use or not to use antibacterial ointment to prevent bacterial infection. (3) Wait for epithelial repair after crusting and self-rescabbing, without forcible scab removal to prevent damage to epidermis and prolong healing time. (4) After debridement of the exposed area, avoid sunlight or apply sunscreen to prevent hyperpigmentation. If pigmentation occurs, apply depigmentation cream, or wait for more than 3 months for natural fading. (5) After debridement, check whether there is any residue of lesion, if there is residue, you should follow up and make up the treatment as early as possible.