Cryotherapy uses the low temperature generated by liquid nitrogen refrigerant (-196°C) to apply to the lesioned skin tissue, causing necrosis to occur in order to eliminate the lesion. There are contact freezing and jet freezing. After freezing, local tissue whitening and swelling can be seen, blistering occurs within 1-2 days, then drying and crusting, about 1-2 weeks to remove the crust. Indications: (1) strawberry hemangioma, angiokeratoma; (2) lymphadenoma; (3) early scarring; (4) common warts and plantar warts; (5) pyogenic granuloma; (6) skin cancer; (7) nodular itchy rash; (8) rosacea with obvious capillary dilation. The side effects and their treatment: 1, pain: cryotherapy method, 1-2 days after treatment will appear pain. The pain is generally very mild. Most people can tolerate. Occasionally there are individual patients with severe pain, can take painkillers. 2, edema: cryotherapy local thawing that began to edema, up to the peak within 24 hours, edema to the head, face, neck and lower limbs and other parts of the tissue is more common. Generally do not need to deal with, a few days after the self-receding. 3, blister: freezing dose, 1-2 days can occur in varying sizes of blisters, and even blood blisters, vesicles, can be extracted under aseptic conditions, and then coated with 75% ethanol to prevent infection. 4.Bleeding: Freezing does not cause much damage to blood vessels >2mm in diameter, so bleeding rarely occurs after freezing of hemangioma. However, larger hematomas should be closely observed for 2 weeks and patients should be taught the method of pressure to stop bleeding to avoid accidents. 5.Pigmentation loss: After cryotherapy, the local pigmentation may be reduced or even the local hair may become white, which may be related to the sensitivity of melanin to freezing, and these changes usually return to normal within 6-12 months. 6, hyperpigmentation: for the secondary changes of inflammation caused by cryotherapy, generally within 6 months to subside on their own. 7, scarring: freezing mostly causes atrophic scars and occasionally a few hyperplastic scars.