Frown lines are the indentations in the skin that usually resemble the number 11, which develop between the eyebrows. They are usually caused by repetitive frowning or squinting, and even though these lines usually appear with age, they can also be experienced by younger people.
Over time these expression lines become more pronounced as the skin loses its ability to bounce back, due to decreasing levels of collagen and elastin as we age. These are the proteins responsible for maintaining the skins elasticity.
Although these lines do not pose any risk to health they can be associated with a permanently angry or concerned appearance. This can lead to feelings of self consciousness and a lack of confidence in both men and women.