Lasers work by producing short pulses of intense light that pass harmlessly through the top layers of the skin to be selectively absorbed by the tattoo pigment. This laser energy causes the tattoo pigment to fragment into smaller particles that are then removed by the body's immune system. Researchers have determined which wavelengths of light to use and how to deliver the laser's output to best remove tattoo ink. (If you're wondering if the laser might also remove normal skin pigment, don't worry. The laser selectively targets the pigment of the tattoo without damaging the surrounding skin.)

More than one treatment, which actually only takes minutes, is usually needed to remove an entire tattoo -- the number of sessions depends on the amount and type of ink used and how deeply it was injected. Three-week intervals between sessions are required to allow pigment residue to be absorbed by the body.
Side effects of laser procedures are generally few but may include hyperpigmentation, or an abundance of color in the skin at the treatment site, and hypopigmentation, where the treated area lacks normal skin color. Other possible side effects include infection of the site, lack of complete pigment removal and a 5 percent chance of permanent scarring.