Liquid nitrogen is sprayed at specific lesions and freezes a localised patch of the skin to -70C. This causes a freeze burn at the treatment site. This burn causes the upper layer of skin to separate from the lower layer and effectively removes sun damaged tissue (actinic keratosis). The underlying collagen is unaffected by freezing and therefore the burn heals without scarring. Pigmented cells are also susceptible to cold and liquid nitrogen can be used to treat sun spots and pigmented actinic keratosis also. Extra care must be taken when liquid nitrogen is used to treat pigmented skin types as it can leave areas of loss of pigment.
Liquid nitrogen is quick and easy but uncomfortable. Following treatment a blister will usually develop at the treatment site. This blister will usually heal in 6-10 days. Usually the blisters do not require treatment, but larger blisters can be burst using a sterile needle and then an antibiotic or antiseptic cream should be applied 2-3 times daily.