What is cryotherapy? Cryotherapy is the use of low temperature to destroy the diseased tissue of the skin for the purpose of treating the disease. It is commonly used for a variety of benign skin, precancerous lesions and even superficial skin malignancies. Clinical treatment is usually performed with liquid nitrogen (boiling point -195.6°C), which is widely used because it is safe, effective, inexpensive and easy to use. A series of postoperative reactions may occur in the local skin tissue after cryopreservation: swelling, pain, and sometimes blisters or hemorrhages. The postoperative reactions reach their peak in about a day or two, with local tissue necrosis turning purple and black, and crusting, while the tissue beneath it regenerates and repairs, and eventually the crust falls off and the wound heals. Each treatment to healing usually takes 7-14 days. Scarring and hypopigmentation may remain after healing, but can gradually improve with time. Number of treatments The number of treatments is often related to the thickness of the lesion. Many superficial skin conditions, such as seborrheic keratosis and solar keratosis, can be removed with a single treatment. However, there are some conditions, such as plantar warts, that sometimes require several or even more than 10 repeated treatments to clear. Treatment interval The treatment interval depends on the response to the treatment, and in most cases the treatment is repeated once every 2-3 weeks. Post-operative precautions (1) There will be varying degrees of swelling and pain after freezing, most of which can be tolerated and can be relieved after 1-2 days, or you can take painkillers if the pain is severe. (2) If the postoperative pain persists for more than 4-5 days, or if the wound surface is red, swollen, painful or even purulent discharge appears, there may be secondary infection, and it is necessary to follow up with the outpatient clinic as soon as possible for anti-infection treatment. (3) If blisters or blood blisters occur, do not be overly nervous, as this is a common postoperative reaction that can be absorbed on its own. If it affects normal life, you can use a sterile syringe to extract vesicular fluid after local disinfection, retain the top of the blister, and apply pressure bandage. (4) If the blister or blood blister ruptures on its own before its underlying epidermis has healed, local antimicrobial ointment can be applied to prevent secondary bacterial infection of the trauma. (5) Keep the frozen trauma clean, and if the blister is not broken, it can take on water and can be washed. It can be washed daily with mild soap and water to keep the area clean, but forceful rubbing, kneading, rubbing and tearing should be avoided. (6) Let the scab fall off on its own as much as possible, avoid forcibly tearing off the scab, damaging the skin under repair and prolonging the healing time. (7) Pay attention to anti-freezing in winter treatment and sun protection in summer treatment. (8) If there are still residual lesions after treatment, please follow up promptly and provide further treatment.