Formerly, tattoos were removed by skin abrasion techniques using salt, milling processes, chemical burning or electrocoagulation, inevitably resulting in permanent scarring and often incomplete removal of the pigment. Surgical tattoo removal introduced an alternative technique, but still left unsightly scars.
Argon lasers were used from 1980, but the CO2 used also resulted in incomplete removal of pigment and left scars due to inadequate selectivity.
Tattoo removal is now done with Q-Switched lasers; these machines impart a laser pulse of very short duration (nanoseconds, ie a few billionths of a second). These pulses destroy the cells that contain the pigment granules, breaking them down into smaller fragments (10 to 100) which over the course of a few days or weeks are absorbed by macrophages in the body and eliminated.
A number of treatments with roughly a month between sessions ensures progressive, natural disappearance of the tattoo. The pulses of very short duration avoid overheating of the skin and eliminate the formation of scars (selective photothermolysis).
Neodymium - Yag Q-Switched lasers emit a choice of 4 rays of different wavelengths, each designed for removal of specific colours:
Infections may occur as with any skin trauma.
Persistent erythema, discolouration (hypo- or hyperpigmentation of the treated skin): this can occur in the first few weeks after treatment from direct exposure to excessive cold, heat or sunlight.
Even in the most successful cases there may be a faint residue of the tattoo when the treatment is finished, a kind of shadow that we call a "ghost tattoo". This may remain for several years or permanently.