Hair grows everywhere on the human skin except on places like the palms of our hands and the soles of our feet, our eyelids and belly buttons, but many hairs are so fine they’re virtually invisible. Hair is made up of a protein called keratin that is produced in hair follicles in the outer layer of skin. As follicles produce new hair cells, old cells are being pushed out through the surface of the skin at the rate of about six inches a year. The hair you can see is actually a string of dead keratin cells. The average adult head has about 100,000 to 150,000 hairs and loses up to 100 of them a day; finding a few stray hairs on your hairbrush is not necessarily cause for alarm.
At any one time, about 90% of the hair on a person’s scalp is growing. Each follicle has its own life cycle that can be influenced by age, disease, and a wide variety of other factors.
Hair Loss Symptoms
The main symptom of alopecia is losing more hair than usual, but this can be harder to identify than you might think.
The following symptoms can provide some clues:
- Widening part. If you part your hair, you might start to notice your part getting wider, which can be a sign of thinning hair.
- Receding hairline. Similarly, if you notice your hairline looking higher than usual, it may be a sign of thinning hair.
- Loose hair. Check your brush or comb after using it. Is it collecting more hair than usual? If so, this may be a sign of hair loss.
- Bald patches. These can range in size and can grow over time.
- Clogged drains. You might find that your sink or shower drains are clogged with hair.
- Pain or itching. If you have an underlying skin condition causing your hair loss, you might also feel pain or experience itching on your scalp.
Types of Hair Los
Hair loss, also called alopecia, is a disorder caused by an interruption in the body’s cycle of hair production. Hair loss can occur anywhere on the body, but most commonly affects the scalp. On average, the scalp has 100,000 hairs that cycle through periods of growing, resting, falling out, and regenerating.
- Androgenetic: Alopecia Androgenetic alopecia is the most common type of hair loss, affecting more than 50 million men and 30 million women in the United States.
- Male Pattern Hair Loss: In men, hair loss can begin any time after puberty and progress over the course of years or decades. It starts above the temples and continues around the perimeter and the top of the head, often leaving a ring of hair along the bottom of the scalp.
- Female Pattern Hair Loss: In women, hair slowly thins all over the scalp, but the hairline usually doesn’t recede.
- Telogen Effluvium: Telogen effluvium, a type of hair loss, occurs when large numbers of follicles on the scalp enter the resting phase of the hair growth cycle, called telogen, but the next growth phase doesn’t begin.
- Anagen Effluvium: Anagen effluvium is rapid hair loss resulting from medical treatment, such as chemotherapy.
- Alopecia Areata: Alopecia areata is an autoimmune condition, which means the body’s immune system attacks healthy tissues, including the hair follicles.
- Tinea Capitis: Tinea capitis, also called scalp ringworm, is a fungal infection of the scalp that’s a common cause of hair loss in children.
- Cicatricial Alopecia: Cicatricial alopecia, also known as scarring alopecia, is a rare type of hair loss in which inflammation destroys hair follicles and causes scar tissue to form in their place. After scar tissue forms, hair doesn’t regrow.
- Lichen Planopilaris
- Discoid Lupus Erythematosus
- Folliculitis Decalvans
- Dissecting Cellulitis of the Scalp
- Frontal Fibrosing Alopecia
- Central Centrifugal Cicatricial Alopecia
What Causes Hair Loss?
Hormones, such as abnormal levels of androgens (male hormones normally produced by both men and women)
Genes, from both male and female parents, may influence a person’s predisposition to male or female pattern baldness.
Stress, illness, and childbirthcan cause temporary hair loss. Ringworm caused by a fungal infection can also cause hair loss. Learn what you can do to help reverse hair loss caused by stress.
Drugs, including chemotherapy drugs used in cancer treatment, blood thinners, beta-adrenergic blockers used to control blood pressure, and birth control pills, can cause temporary hair loss.
Medications and supplements, Hair loss can be a side effect of certain drugs, such as those used for cancer, arthritis, depression, heart problems, gout and high blood pressure.
Radiation therapy to the head, The hair may not grow back the same as it was before.
A very stressful event, Many people experience a general thinning of hair several months after a physical or emotional shock. This type of hair loss is temporary.
Hair styles and treatments, Excessive hairstyling or hairstyles that pull your hair tight, such as pigtails or cornrows, can cause a type of hair loss called traction alopecia. Hot-oil hair treatments and permanents also can cause hair to fall out. If scarring occurs, hair loss could be permanent.
Other Causes
Other causes of hair loss, especially if it is in an unusual pattern, include:
- Alopecia areata (bald patches on the scalp, beard, and, possibly, eyebrows; eyelashes may fall out)
- Anemia
- Autoimmune conditions such as lupus
- Burns
- Certain infectious diseases such as syphilis
- Excessive shampooing and blow-drying
- Hormone changes
- Thyroid diseases
- Nervous habits such as continual hair pulling or scalp rubbing
- Radiation therapy
- Tinea capitis (ringworm of the scalp)
- Tumor of the ovary or adrenal glands
- Hair styles that put too much tension on the hair follicles
- Bacterial infections of the scalp
