Causes

• Alopecia areata
  Alopecia areata
  Alopecia areata is a medical condition in which hair is lost from some or all areas of the body, usually from the scalp. Because it causes bald spots on the scalp, especially in the first stages, it is sometimes called spot baldness. In 1–2% of cases, the condition can spread to the entire scalp ...
  
  
• Anagen effluvium
  Anagen effluvium
  Anagen effluvium is the pathologic loss of anagen or growth-phase hairs. Classically, it is caused by radiation therapy to the head and systemic chemotherapy, especially with alkylating agents....
  
  
• Androgenetic alopecia
  Androgenetic alopecia
  Androgenic alopecia is the most common cause of hair loss and thinning in humans. Variants appear in both men and women. Androgenic alopecia also occurs in chimpanzees, and orangutans. In humans, this condition is also commonly known as male pattern baldness...
  
  
• Dermatopathia pigmentosa reticularis
  Dermatopathia pigmentosa reticularis
  Dermatopathia pigmentosa reticularis is a rare, autosomal dominant congenital disorder that is a form of ectodermal dysplasia...
  
  
• Telogen effluvium
  Telogen effluvium
  Telogen effluvium is a scalp disorder characterized by thinning/shedding of hair resulting from the early entry of hairs into the telogen phase.Emotional or physiological stressful events may result in an alteration of the normal hair cycle....
  
  
• Trichotillomania
  Trichotillomania
  Trichotillomania, which is classified as an impulse control disorder by DSM-IV, is the compulsive urge to pull out one's own hair leading to noticeable hair loss, distress, and social or functional impairment. It is often chronic and difficult to treat....
  
  (Trichotillosis)