Hair Loss Science
Reasons for Hair Loss (Alopecia) and Is Hair Loss Preventable?
Hair loss, or alopecia, affects both men and women. Often it is temporary and the hair grows back once the underlying cause is gone, but pattern baldness is permanent. Here are the common reasons for hair loss, and what can stop or slow it.
Key takeaways
- Shedding 50 to 100 scalp hairs a day is normal. Excessive hair loss is usually temporary: alopecia areata, trauma, chemotherapy, harsh styling, poor nutrition and thyroid imbalance can all cause it.
- Androgenetic alopecia, known as male and female pattern baldness, is the permanent kind. It stems from hereditary and environmental factors and is linked to the hormone DHT.
- Women face some causes of their own: iron-deficiency anemia from menstruation, the stress and hormonal shifts of childbirth, and birth control pills or PCOS in genetically predisposed women.
- Several effective solutions can stop or slow further hair loss: minoxidil for men and women, finasteride for men, and laser therapy, which can stimulate growth.
Hair may not be vital for our physical well-being, but it is an important aspect of our physical appearance and often determines how other people perceive us. Although people tend to associate hair loss (alopecia) with men, the truth is that both men and women can be affected.
Reasons for hair loss include hormonal imbalance, diseases and stress, to name a few. Hair loss is often temporary, and hair grows back once the underlying cause has been eliminated. In other cases, it is permanent. Some causes are gender-specific, while others affect both sexes.
A glimpse into hair anatomy and growth
Hair structure and growth may seem simple at first glance, but they are actually quite complex. This partly explains why the solution to the problem of hair loss has eluded scientists for so long.
Each hair consists of a follicle, which roots the hair in the scalp, and a hair shaft (the visible part of the hair), made of a sturdy protein called keratin. Hair grows from the base of the follicle and gradually emerges through the skin. It is lubricated by sebaceous glands located within the hair follicles.
The hair growth cycle has three distinct phases: anagen (growth), catagen (cessation) and telogen (rest). All three phases occur at the same time across the scalp. Hair growth and structure also vary through the stages of life, under the influence of hormones.
Normal vs. excessive hair loss
People shed an average of 50 to 100 scalp hairs a day. This is part of the normal hair growth cycle, as new hairs grow in their place. In some people, follicles stop growing hair as the years pass, which is part of the normal aging process.
When more hair is lost than regrown, we are talking about excessive hair loss. The medical term for hair loss is alopecia. In most cases, excessive hair loss is temporary: shedding subsides and hair growth returns to normal once the underlying causes are remedied. This usually takes 3 to 4 months.
50 to 100
scalp hairs shed a day, on average
3 to 4
months, usually, to recover once the cause is remedied
Causes of temporary hair loss
A number of conditions can cause hair to fall out temporarily. Here are the common ones.
Alopecia areata
This condition is autoimmune in origin. The body fails to recognize its own tissues and turns its immune response against the “invader.” Hair falls out in patches.
Trauma
Physical trauma, such as a major medical procedure, a car crash or a severe illness, can trigger a type of temporary hair loss known as telogen effluvium (outflow). In this type of hair loss, the stressful event forces more hairs than normal into the shedding stage.
Emotional shock can also result in hair loss, but this is less likely to occur. More often than not, it aggravates a pre-existing hair-shedding issue.
Chemotherapy
Hair loss is a side effect of certain anticancer drugs. It can range from slight thinning to complete baldness. This type of hair loss is called anagen effluvium. Whether hair loss happens depends on the drug type and dosage.
Chemotherapy-induced hair loss comes from the way cancer drugs work. They are designed to interfere with the growth of cancer tissue, which is characterized by rapid cell division. This action is non-selective, however, so it also affects healthy, rapidly growing cells, including hair. In addition to scalp hair, the eyelashes, eyebrows, armpit hair, pubic hair and body hair may also fall out. In most cases, hair regrows 3 to 10 months after the treatment.
Harsh hair care and styling
Aggressive hair care products and hairstyles, such as cornrows and tight ponytails, can damage the roots and lead to hair loss. This is known as traction alopecia.
Nutrition
Prolonged nutritional deficiency states, including malnutrition and starvation, can affect hair growth. Insufficient protein intake forces the body to ration its resources and building blocks by shutting down hair growth. A lack of B-complex vitamins (notably B6 and B12) or iron can also cause hair loss. Keep your diet nutritious and avoid crash diets.
Thyroid imbalance
Chronic and severe hypothyroidism and hyperthyroidism can cause temporary hair loss. Successful treatment of the condition resolves the problem, but it may take several months for hair growth to return to normal.
Free consultation
Find out what is behind your hair loss
Not sure whether your hair loss is temporary or permanent? Consultations at Advanced Hair Restoration® are free and in person, so a hair loss professional can examine your scalp and donor area directly and map your exact graft count.
Permanent hair loss
Permanent hair loss, or androgenetic alopecia, is known as male pattern baldness in men and female pattern baldness in women. Its causes include a combination of hereditary and environmental factors.
Androgenetic alopecia is linked to an inherited sensitivity of hair follicles to DHT (dihydrotestosterone), a derivative of the male hormone testosterone, which women also have in minute amounts. In short, DHT causes hair follicles to shrivel up, which prevents normal hair growth.
Male pattern baldness
It usually starts as a receding hairline and progresses to baldness, predominantly in the crown area (the top of the head). Follicles at the back and sides of the head are less affected.
Female pattern baldness
It appears as thinning hair at the top of the head and eventually at the sides. It usually starts at menopause, since during the reproductive years the actions of DHT are counteracted by the hormone estrogen. In women, thinning rarely progresses to actual baldness. Without treatment, this type of hair loss is permanent.
Female hair loss
Some types of hair loss are gender-specific and affect only women, mainly because of differences in physiology. Common reasons for female hair loss include:
- Iron-deficiency anemia. Women regularly lose iron as a result of menstruation, and a lack of iron can lead to hair loss.
- Hormones and stress. The stress of childbirth and hormonal fluctuations after pregnancy can push hair follicles into the shedding phase. The condition typically abates about three months after childbirth.
- Birth control pills and polycystic ovarian syndrome (PCOS). Both can cause excessive hair loss and thinning in genetically predisposed women.
Is hair loss preventable?
The short answer
Several effective solutions can help stop further hair loss or slow its rate.
- Minoxidil (Rogaine foam). Recommended for both men and women, it can stop the progression of hair loss and even promote hair growth.
- Finasteride (Propecia pills). Recommended for men, it can also stop the progression of hair loss and even promote hair growth.
- Laser therapy. It can stimulate hair growth by exposing hair follicles to light set at a specific wavelength.
Related reading: What Causes Hair Loss, What to Expect at Your Hair Restoration Consultation and Hair Transplant 101.
Questions patients ask
Hair loss questions
How much hair loss is normal?
People shed an average of 50 to 100 scalp hairs a day. This is part of the normal hair growth cycle, as new hairs grow in their place. When more hair is lost than regrown, the hair loss is excessive; the medical term for hair loss is alopecia.
Is hair loss temporary or permanent?
It depends on the cause. In most cases, excessive hair loss is temporary: alopecia areata, physical trauma, chemotherapy, harsh hair care and styling, nutritional deficiencies and thyroid imbalance can all make hair fall out, and growth returns to normal once the underlying cause is remedied. Androgenetic alopecia, known as male or female pattern baldness, is permanent hair loss.
What causes hair loss in women?
Female pattern baldness thins the hair at the top of the head and eventually the sides. It usually starts at menopause and rarely progresses to actual baldness. Other common reasons for female hair loss are iron-deficiency anemia from menstruation, the stress of childbirth and hormonal fluctuations after pregnancy, and birth control pills or polycystic ovarian syndrome (PCOS) in genetically predisposed women.
Is hair loss preventable?
There are several effective solutions to help stop or reduce the rate of further hair loss. Minoxidil (Rogaine foam), recommended for both men and women, and finasteride (Propecia pills), recommended for men, can stop the progression of hair loss and even promote hair growth. Laser therapy can stimulate hair growth by exposing hair follicles to light set at a specific wavelength.
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Next step
Get a clear answer about your hair loss
Whether your hair loss is temporary or permanent, knowing the cause is the first step. Schedule a free consultation with Advanced Hair Restoration®. Consultations are in person, so a hair loss professional can examine your scalp and donor area directly and map your exact graft count.