Vellus hairs are light peach fuzz. Everyone is born with vellus hair, and during puberty, an increase in androgenic hormone levels causes them to be replaced with dark, thick terminal hair. Terminal hairs only grow in areas of a woman’s body that are sensitive to these hormones, such as the pubic area and underarms. Males lose their vellus hair and develop terminal hair in more areas of the body than women because their androgenic hormone levels are much higher. At puberty, men develop terminal hair on their face, stomach, legs, arms, feet, chest, and back, while women will retain most of their vellus hair.
It is these vellus hairs that are the most difficult to get rid of during laser hair removal procedures. Since they contain less melanin, they are harder for the laser to detect. Still, most areas of a man’s or woman’s body can be treated with a medical laser for permanent hair removal.
Every person is different and there are several factors that contribute to the way vellus hairs and terminal hairs grow. Since there are so many factors that contribute to the success of laser hair removal treatments, it’s impossible to say whether lasers will eliminate all vellus hair.