Normally, the hair at the telogen stage, which has completed its development and is disconnected from the follicle, falls spontaneously or because of external factors such as combing, shampoo washing, brushing, hair styling, and a new one comes out after a while. In this cyclic process, 25-100 hair strands fall out in a day under normal conditions. However, number of lost hairs above this number indicate a "hair loss problem". This problem can be permanent or temporary for various reasons. The follicle cells in the anagen phase are affected by toxic (mercury, boric acid, thallium, colchicine) substances, antimitotic substances (radiotherapy applied to the head, systemic chemotherapy) and severe protein deficiency and get broken or fall out in a few hours to 2 weeks (Anagen effluvium). In people who do not have hair problems, the number of follicles in the anagen phase is 84%, the number of those in the catagen phase is 2%, and the number of those in the telogen phase is 14%. Depending on the factors affecting the telogen phase, the number of hairs in this phase may exceed 25%. There are many factors that cause the hair strands to enter the telogen stage and fall (Telogen effluvium) in a shorter time than normal.

Here are some of the factors:

• Post febrile telogen effluvium
• Diseases
• Drugs used
• Cosmetic products and applications
• Psychogenic telogen
• Temporary hormonal imbalances
• Malnutrition
• Smoking
• Chemical and physical agents
• Seasonal changes
• Metabolism and endocrine system

In order to solve the problem of hair loss, the type of hair loss should be examined by a specialist (dermatologist) first. In "Androgenetic Alopecia" (AGA), which is the most common cause of hair loss, hair follicle activity decreases with the effect of androgens, the anagen phase becomes shorter, hair strands gradually turn into thin vellus hairs without pigment.