Thermolysis is a newer method, which uses localized heat, almost like a miniature microwave oven inside the follicle, to destroy the structures in the follicle. It is EXTREMELY fast, typically only taking a few hundredths or tenths of a second to work, but it requires very precise placement of the probe because the heat only targets a very small area. Because of this, it is also important to stretch the skin so that the tip of the probe can reach the terminus of the follicle, where the papilla that grows the hair is, making it harder to treat curly or distorted hair follicles.
Thermolysis can be performed on any hair color or type, unlike laser hair removal, where the hair has to be pigmented (dark) to be removed. Thermolysis is popular with those that want to remove blonde, white or grey hairs. The most popular areas are the face and underarms. Thermolysis is permanent but does require multiple sessions.