The types of abnormal hair loss are mainly divided into:
1. Androgenetic Alopecia
Androgenetic alopecia or hereditary alopecia is the most common type of hair loss and is progressive. Men and women with androgenetic alopecia are born with hereditary hair follicles, also known as dihydrotestosterone (DHT) sensitive. This hormone causes the hair follicle to become miniaturized over time, resulting in thinner hair. Eventually, the hair follicles stop producing normal hair, leaving only “fluff”.
2. Alopecia Areata
Also known as ghost shaving, it is a sudden onset of plaque-like hair loss. The scalp is normal in the lesion, and there is no inflammation or subjective symptoms. With lymphocyte infiltration around the hair follicle, this disease sometimes is combined with other autoimmune diseases, so medically it is currently believed that the occurrence of this disease may have an autoimmune pathogenesis. In addition to genetic quality, it may also be associated with neurological trauma, mental disorders, infections, and endocrine disorders.
3. Telogen Effluvium
The reason for this is that many hair follicles suddenly enter the “quiet period” early, during which the hair becomes thinner overall. Telogen effluvium may be caused by many factors, including newborn hair loss, postpartum hair loss, mental and emotional factors, nutritional deficiencies, thyroid imbalance, surgery, medication, frequent staying up late, starting or stopping oral contraceptives, overeating, etc.
4. Anagen Effluvium
This is the sudden rapid shedding of hair in the growth stage. This may be due to chemicals or drugs used to treat tumors, such as antimetabolites, alkylating agents and mitotic inhibitors, or chemotherapy for cancer treatment or radiation therapy.
5. Cicatricial Alopecia
Most symptoms of this disease first manifest as small plaques of hair loss that may expand over time. In addition to genetic factors, it may also be caused by other factors such as chemical relaxants, tightly woven or excessively pulled hair, deep burns, electric injuries, radiation dermatitis, immune inflammatory diseases (lichenus, discoid lupus erythematosus, scleroderma, etc.), infectious diseases, cutaneous carcinoma and the like, which can seriously damage the skin tissue and the hair follicles, forming scars that make the hair follicles unable to regenerate, resulting in permanent hair loss.
6. Scalp Folliculitis
Scalp folliculitis is an inflammatory change around the follicular orifice caused by pyogenic cocci. It begins with a red-filled papule and then rapidly develops into a papular abscess. In the early stages, hair may still be in the hair follicle, but as the disease progresses, it will fall out. In severe cases, inflammation can destroy hair follicles and cause permanent hair loss.
7. Traction Alopecia
Traction alopecia is caused by damage to the hair follicle with long-lasting stretching. Repeatedly tied tight hair styles, such as ponytails or braids, can cause traction alopecia. This condition of hair loss usually occurs near the temple or along the hairline.
This is an impulsive control disorder that drives individuals to pull out their hair, and the patient is unconsciously urged to pluck their hair, eyelashes, beard, nose hair, pubic hair, eyebrows, or other body hair repeatedly. Usually, it can cause spotted baldness on the hair, eyebrows and/or eyelashes.
9. Trichorrhexis Nodosa, also known as Piedra
This can occur at any age in both sexes, but is more common in women. One or several yellow-white or gray-white nodules appear on the hair shaft, and the hair is brushed at the break. The hair looks like brushes embedded oppositely at the place where it is not completely broken. In addition to genetic and pathological factors, factors such as infection or nutritional deficiencies may also be associated with the disease. In some cases, excessive use of chemicals and heating styling tools can trigger this disease.
10. Tinea Capitis
Tinea capitis is a fungal infection and superficial fungal infection of the scalp, which can be divided into three types according to the pathogen and clinical manifestations: tinea favosa, tinea alba, and trichophytosis capitis. Frequently occurring in children, this highly contagious disease is mainly transmitted through contaminated hair tools and/or through contact with infected animals. Hair loss due to tinea capitis is mainly caused by tinea favosa or tinea alba. If it worsens, it is likely to cause permanent hair loss.
11. Scalp Inflammation
Scalp inflammation causes bacteria to breed and multiply, which fundamentally destroys the epidermal cell tissue, causing cells to break out and body fluids to spill or cell enlargement, as well as fissured capillary membrane and congestion, and local fever. The original epidermal tissue structure is destroyed by the bacteria which rob nutrients, phagocytize normal tissues, and affect cell metabolism and subcutaneous circulation. It causes the hair to loosen or even fall out, which leads to necrosis of epidermal tissue and damage to cells over a large area. A typical one is seborrheic scalp inflammation.