Numerous stretch marks can be caused by some medications like steroids such as cortisone. Stretch marks are developed when the skin is excessively stretched beyond its limit during pregnancy, growth spurts or weight gain.

Collagen production in the dermis of the skin is damaged, and blood vessels dilation causes the development of purplish coloured early stretch marks. The inflammation and collagen disruption may cause the obscuring of production of melanin. After a period, this lacking of pigment leads to the white pigmented scars that we call stretch marks. It can also be caused by the rapid weight gain in a short duration such as puberty or during pregnancy.

Stretch marks can also be formed on children who have rapidly become obese or on teens or adolescents who have undergone growth spurts during puberty. Due to constant repetitive exercises, athletes and body builders can also develop stretch marks. It has even been suggested that stretch marks are caused because of an increased level of a hormone called glucocorticoids circulating through the body. This hormone is produced by the adrenal gland, and its production is increased during pregnancy, adolescence, obesity and weight lifting.

The glucocorticoids affect the dermis or the skin by preventing the fibroblasts from forming elastin fibres and collagen. These are required to keep growing skin firm. What follows is dermal tearing as there is a lack of supportive substance when the skin is being stretched over its limit. Some people can be more prone to getting stretch marks than others. Skin type may be a factor. For example, dryer skin has less elasticity than oily skin, and more likely to develop stretch marks. Stretch marks can also form more easily in the skin with a high proportion of cross-lined collagen that occurs in teenagers.