Nitrogen can used to freeze and destroy superficial skin growths, such as warts and keratoses. Liquid nitrogen causes stinging and some pain during treatment. The discomfort usually lasts less than five minutes. After liquid nitrogen treatment, a patient's skin usually will become swollen and red. Blistering may also occur, but this is the NORMAL, expected reaction. A scab (crust) may form depending on how deep or "hard" the treatment. The scab will fall off by itself in days to weeks. Most or all of the skin growth will usually come off with the scab. If all of the skin growth comes off and the treatment is not too deep, it is likely that new healthy skin will be left behind as it has grown in from the underlying hair pores or the adjacent tissues. In some cases, however the author prefers special care after liquid nitrogen treatment, e.g., the application of a light coat of antibiotic ointment mixed with topical steroid twice daily for a limited time depending upon the treatment location on the body. The skin can be washed as usual and makeup or other cosmetics can be used as customary. If clothing irritates the area, cover it with a small bandage (Band-Aid). Keep in mind, to reduce the chances of scarring or another permanent skin change, that undertreatment means reduced complications. Therefore, sometimes appropriate liquid nitrogen treatment will fail to cure the lesion in question in order to avoid scarring, permanent loss of pigment and other undesirable problems. See Treating Precancers.