Except for the palms of our hands and the soles of our feet, our eyelids, and belly buttons, hair grows everywhere on human skin, yet many hairs are so thin that they are nearly undetectable. Hair is composed of keratin, a protein generated in hair follicles in the skin’s outer layer. As follicles develop new hair cells, old cells are pushed out through the skin’s surface at a rate of around six inches every year.
The visible hair is a thread of dead keratin cells. The typical adult head contains 100,000 to 150,000 hairs and loses up to 100 of them every day; a few stray hairs on your brushes are not the reason for concern.
Approximately 90% of the hair on a person’s scalp is growing at any given moment. Each follicle has its life cycle, which is affected by age, sickness, and a range of other circumstances. There are three stages in this life cycle:
Anagen – active hair growth that typically lasts two to eight years.
Catagen – two to three weeks of transitional hair growth
Telogen – a resting period that lasts approximately two to three months; at the end of the resting phase, the hair is lost, replaced by a new hair, and the growth cycle begins again.
Hair growth diminishes as individuals become older. There are several forms of hair loss, generally known as alopecia:
- Involutional alopecia is a normal condition in which hair thins over time. More hair follicles rest and the remaining hairs grow shorter and fewer in number.
- Alopecia areata is a condition that causes patchy hair loss in children and young adults. This disease can cause full baldness (alopecia totalis). However, in roughly 90% of patients with the disease, the hair grows back within a few years.
- Alopecia Universalis involves the loss of all body hair, including the brows, eyelashes, and pubic hair.
- Trichotillomania is a psychiatric illness in which a person pulls out their hair. It is particularly common in youngsters.
- Telogen effluvium is a transient hair thinning over the scalp caused by changes in the hair development cycle. When a significant number of hairs reach the resting phase at the same time, they shed and thin. Find out what causes telogen effluvium.
- Scarring alopecias cause permanent hair loss. Inflammatory skin problems (cellulitis, folliculitis, acne) and other skin illnesses (such as some types of lupus and lichen planus) can result in scars that impair hair regeneration. Hot combs, as well as hair that is excessively tightly braided and twisted, can cause irreversible hair loss.
What Factors Contribute to Hair Loss?
- Doctors are baffled as to why certain hair follicles are wired to develop faster than others. Several variables, however, may cause hair loss:
- Hormones, such as elevated androgen levels (male hormones normally produced by both men and women)
- Genes inherited from both male and female parents can impact a person’s proclivity for male or female pattern baldness.
- Temporary hair loss can be caused by stress, illness, or delivery. Ringworm, which is caused by a fungal infection, can also result in hair loss. Learn what you can do to help reverse stress-related hair loss. Temporary hair loss can be caused by medicines such as chemotherapy treatments used in cancer treatment, blood thinners, beta-adrenergic blockers used to manage blood pressure, and birth control pills.
- Temporary hair loss can be caused by burns, accidents, and X-rays. Unless a scar is formed, normal hair growth normally resumes once the damage heals. Hair will never regenerate after that.
- Alopecia areata can be caused by an autoimmune condition. The immune system overreacts in alopecia areata for unknown causes, affecting the hair follicles. Hair comes back in most persons with alopecia areata, albeit it may be extremely fine and maybe a lighter color at first before returning to normal hue and thickness.
- Shampooing too frequently, perms, bleaching, and dyeing hair can all contribute to general hair loss by making hair fragile and brittle. Tight braiding, heated curlers, and dragging hair picks through tight curls can all cause hair damage and breakage. These operations, however, do not result in baldness. When the source of the problem is eliminated, hair usually grows back regularly. Even so, significant hair or scalp loss might result in permanent bald patches.
Medical problems. Hair loss can be caused by thyroid illness, lupus, diabetes, iron deficiency anemia, eating disorders, and anemia. Unless there is scarring, as in some instances of lupus, lichen planus, or follicular diseases, hair will usually regrow when the underlying problem is addressed.
Diet. Temporary hair loss can also be caused by a low-protein or extremely calorie-restricted diet. Learn about the foods that can help prevent hair loss.