Liquid Nitrogen is cold. Seriously cold. -196 degrees celcius in fact. It is used to treat a number of skin conditions including: Warts and Verrucas Actinic Keratosis Seborrhoeic Keratosis Some Basal Cell Carcinomas. During treatment, liquid nitrogen is sprayed directly onto your skin, causing the skin layers to freeze. Ice crystals forming in cells destroy them, causing the unwanted tissue to die. Sometimes there is blistering, but often just a hard scab forms which peels off after a few days to a couple of weeks. Liquid nitrogen therapy is mildly uncomfortable. It is well tolerated, even by children provided they are aware it will hurt a little but the pain will not last. The pain is considerably less severe than an insect sting but it can be a little sore for several days after treatment, especially if more aggressive therapy has been required. Sometimes a permanent pale patch may be left where the treatment was applied. This is because pigment bearing cells are slightly more susceptible to damage than others. Because we don't want to damage more skin than is necessary, it is common to require more than one treatment to be required, especially for deeper problems like verrucas. If you still have symptoms at two weeks, come back sooner rather than later (verrucas just keep on growing otherwise and leaving it longer just puts you back to the start)