The commonest cause of hair loss is hereditary. It usually progresses slowly and presents as receding hairline in men and thinning hair in women. Patterned baldness or androgenetic alopecia begins as early as in puberty and is most common in men. It involves thinning and miniaturization of the hair.

Excessive hairstyling, like tying a tight pony tail may cause traction alopecia. Moreover, hot oil hair treatments can cause inflammation of hair follicles which results in hair loss. Scarring can lead to permanent hair loss.

Alopecia Areata: It occurs when the immune system of body attacks hair follicles resulting in sudden hair loss. This presents as smooth bald patches of hair loss over the scalp, beard or other hair-bearing areas of the body.

Scalp Infections: Fungal infections of the hair can cause scaly patches and hair loss. In this condition hair usually grows back after the infection is treated.

Other Skin Diseases: Diseases as lupus, lichen planus cause scarring alopecia.

Hair-Pulling Disorder: Trichotillomania is the condition that urges an individual to pull out their hair from the scalp, the eyebrows or other areas.

Hair loss can occur due to the use of certain medicines for the treatment of medical conditions as cancer, depression, arthritis, heart problems and high blood pressure. Consumption of vitamin A in excess also causes hair loss.

Androgenetic alopecia is also known as patterned hair loss. It is the most common type of hair loss that occurs in both males and females.

Hair may or may not grow back after radiation therapy.

Physical or emotional shock can result in thinning of hair after several months. This hair loss is temporary. Examples of trigger events may include excessive weight loss, surgery, high fever or a death in the family.