Laser energy, through the principle of selective photothermolysis (a process that involves selective absorption of an intense light pulse at wavelengths that are absorbed by the hair follicles, but not by the surrounding tissue), targets the pigment in the hair follicle. This causes destruction of hair follicles while sparing surrounding structures (i.e., the skin). Growing hair is more sensitive to destruction than resting hairs. Many of the lasers listed below utilize epidermal or skin cooling techniques. The effect of cooling the surface of the skin serves to minimize discomfort during treatment while increasing the effectiveness of the laser treatments.

1. Ruby Laser (694 nm, normal mode)
   – All patients will see a growth delay of their hair. Some patients will see a permanent reduction in hair growth.
   – This laser is more effective for dark hair. Blonde and gray hairs are more resistant.
   – White hairs do not respond to treatment
   – Epilaser® (Palomar) and Epitouch® (Sharplan) are examples of ruby lasers
2. Alexandrite Laser (755 nm, normal mode)
   – All patients will see a growth delay of their hair. Some will see a permanent reduction in hair growth.
   – It is effective for dark hair. Blonde and gray hairs are more resistant.
   – White hairs do not respond to treatment
   – It is potentially safer for darker skin than the ruby laser
   – Rapid repetition rates of the laser will reduce treatment time
   – Apogee® (Cynosure) uses a cooling gel on the skin
   – Gentlase® (Candela) uses dynamic cooling spray
3. Pulsed Diode Laser (800nm)
   – Patients with thick or coarse hair will see a delay in hair growth. Some patients will see a permanent reduction in hair growth.
   – It is effective for dark hair. It is not effective for fine hair.
   – Potentially, it is safer for darker skin types
   – LightSheer® (Coherent) uses contact cooling
4. Intense Pulsed Light Source (500-1200 nm)
   – It is effective for dark hair, both fine and coarse
   – It is potentially useful for darker skin types
   – Epilight® (ESC) uses cooling gel
5. Nd:YAG Laser (1064 nm, Q-switched)
   – Permanent hair removal has not been demonstrated
   – It can temporarily remove light hairs
   – It is potentially safe for all skin types, and causes the least epidermal damage of all treatments.
   – Carbon suspension is applied to skin in some treatments
   – There is a lower risk of epidermal damage
   – Short operative times are required
   – It causes the least discomfort of all laser hair removal treatments