Cryosurgery uses liquid nitrogen (CO2), a cold liquefied gas with a temperature of 196 degrees below zero Celsius (-321 degrees Fahrenheit). It is used to freeze and destroy superficial skin growths such as warts and keratoses. Liquid nitrogen causes stinging and mild pain while the growth is being frozen and then thaws. This discomfort usually lasts for less than five minutes.

After a liquid nitrogen treatment, the treated skin becomes swollen and red, and may blister. A scab or crust forms, which falls off by itself in one to three weeks. The skin growth will also come off with the scab, leaving healthy new skin.

It's important to note that cryotherapy doesn't always work, and can be expensive. Sometimes multiple treatments are required, and new warts or keratoses can reoccur in the same spot. Also, the procedure may leave a scar.