IPL and lasers target melanin (color) in the hair. In the active growth cycle of hair (about 10-15%) the heat reaches the root and stem cells in the follicle and disables them. The other hair will be stunned but will grow back. That is why on average 6-8 treatments will be required for 70-90% hair loss. The amount of treatments will be influenced by amount of hair, skin color and regularity of treatments. Facial hair can be stimulated by hormones or other problems like thyroid, high testosterone levels, cystic ovaries, pregnancy etc. There are 10% of people that do not respond to laser hair removal for unknown reasons. Your technician will be able to answer all questions for you. more... See more text