The causes of hair loss are diverse and many of them are investigated insufficiently. It is assumed that premature hair loss is programmed genetically, and that its degree is determined by expressiveness of corresponding genes. Thus hair follicles decrease in size under the influence of male hormones when the period of puberty is over. The quantity of them does not decrease until late stages of baldness, but still hair becomes so small that are not visible to the naked eye.

Among women the cause of hair loss can be an hyper-sensitivity to male hormones or their increased amount in the body because of the following diseases: polycystic ovaries, congenital dysfunction of cortex of adrenal glands, Cushing syndrome, tumours of adrenal glands and ovaries.

Symptomatic alopecia can accompany many hardly proceeding acute and chronic diseases and it also can be connected with intoxication, metabolic disorders, disharmonosises. Alopecia, or hair loss, rather often occurs in case of syphilis, diseases of circulatory system, avitaminosises (especially A, C and B), lingering fever (for example, malaria), chemo- and radiotherapy of cancer patients, hypothyroidism and other endocrine diseases after carrying out of extensive surgical interventions, or hardly proceeding labor. A number of medications can also cause intensive loss of hair. Among them are: antineoplastic preparations, colchicine, antiepileptic preparations, antithyroid agents, heavy metals, anticoagulative preparations (heparin, coumarin).

Lupus erythematosus, deep pustular (furuncules, carbuncles) or fungoid (favus, trichophytosis) affection of the scalp can also be the cause of cicatricial alopecia.

There are two basic mechanisms in the process of hair loss development: loss of hair in a phase anagen (active growth of a hair follicle) and loss of hair during the period of telogen (when growth of a follicle stops). The first type of hair loss is marked in case of direct damage of the extremely sensitive growth cells of follicles (for example, ionizing radiation of beam therapy). As the result, the bulb of hair makes thinned core, which is gradually pointed and becomes very fragile. Hair drops out or collapses at the slightest influence. Duration of the second phase, the phase of telogen, makes about 3 months, in the end of which hair drops out "physiologically".