What does cryotherapy do to the skin.

The term ‘cryotherapy’ or ‘cryosurgery’ is the term used to describe the removal of skin lesions by freezing them. The most common agent used is liquid nitrogen, but carbon dioxide or nitrous oxide may also be used effectively and will produce the same results.

The cryogenic agent is usually applied to the skin by using various types of spray gun, such as the CryoPen™ which emits a fine jet of nitrous oxide under high pressure. Other less common application methods include using a metal probe or a cotton bud.

What happens on a cellular level during cryotherapy?

The effects of applying low temperature to the skin gradually increases as the temperature drops. Initially proteins and lipids, as well as the metabolism of the cell is altered. As the temperature drops below 0°C, first the water outside the cell begins to crystallise, causing the cell to dehydrate. At temperatures below −20°C, the water inside the cell starts to crystallise, and at −40°C intracellular ice formation is certain.

As the cells thaw, the ice crystals fuse to form larger crystals. These larger crystals cause damage to the cell walls. As the ice melts it causes the pressure of fluids inside and outside the cell to become imbalanced, which exerts extra pressure on the cell wall.

The whole process of rapid freezing and thawing of the cells causes a loss of circulation, and deprives the cell of oxygen. As the cell returns to normal temperature, the damaged cell walls cause excess fluids to build up and micro blood-clots to form, ending up in the stagnation of blood and ultimately in cell death.

The average human skin cell is about 30 micrometres in diameter. The above process is replicated in all cells exposed with cryotherapy, leading to the destruction and shedding of unwanted skin lesions.

Refrences: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1472868/