Types of Hair Loss

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.

A hair growth cycle consists of three phases. During the anagen phase, hair grows actively. This phase may last for years. During the catagen phase, hair stops growing and separates from its follicle, which is the structure beneath the skin that holds the hair in place. The catagen phase lasts about 10 days. During the telogen phase, the follicle rests for two or three months, and then the hair falls out. The next anagen phase begins as a new hair grows in the same follicle. Most people lose 50 to 100 hairs per day as part of this natural cycle.

If this cycle is disrupted, or if a hair follicle is damaged, hair may begin to fall out more quickly than it is regenerated, leading to symptoms such as a receding hairline, hair falling out in patches, or overall thinning.

Hair loss may be linked to a person’s genetics, although many medical and behavioral conditions may interrupt the growth cycle and cause hair loss. At NYU Langone, dermatologists specialize in hair and scalp disorders and can identify the type of hair loss, as well as its cause.

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. Commonly known as male pattern hair loss or female pattern hair loss, androgenetic alopecia is hereditary but can be managed with medication or surgery.

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. Many men with male pattern hair loss eventually become bald.

Female Pattern Hair Loss

In women, hair slowly thins all over the scalp, but the hairline usually doesn’t recede. Many women experience this type of hair loss as a natural part of aging, although hair loss may begin any time after puberty. Female pattern hair loss can cause hair to thin dramatically, but only rarely does it lead to baldness.

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. This causes hair to fall out all over the scalp without new hair growth.

Telogen effluvium does not generally lead to complete baldness, although you may lose 300 to 500 hairs per day, and hair may appear thin, especially at the crown and temples.

A medical event or condition, such as a thyroid imbalance, childbirth, surgery, or a fever, typically triggers this type of hair loss. Telogen effluvium may also occur as a result of a vitamin or mineral deficiency—iron deficiency is a common cause of hair loss in women—or the use of certain medications, such as isotretinoin, prescribed for acne, or warfarin, a blood thinner. Starting or stopping oral contraceptives (birth control pills) may also cause this type of hair loss.

Telogen effluvium usually begins three months after a medical event. If the triggering event is temporary—for example, if you recover from an illness or stop taking the medication causing the hair loss—your hair may grow back after six months. Telogen effluvium is considered chronic if hair loss lasts longer than six months.

For reasons that are unclear to doctors, this type of hair loss may last for years in some people. If hair doesn’t regrow on its own, our dermatologists can offer medication that can help.

Anagen Effluvium

Anagen effluvium is rapid hair loss resulting from medical treatment, such as chemotherapy. These potent and fast-acting medications kill cancer cells, but they may also shut down hair follicle production in the scalp and other parts of the body. After chemotherapy ends, hair usually grows back on its own. Dermatologists can offer medication to help hair grow back more quickly.

Alopecia Areata

Alopecia areata is an autoimmune condition, which means the body’s immune system attacks healthy tissues, including the hair follicles. This causes hair to fall out and prevents new hair from growing.

This condition can affect adults and children, and hair loss can begin suddenly and without warning. Hair from the scalp typically falls out in small patches and is not painful. Hair in other parts of the body, including the eyebrows and eyelashes, may also fall out. Over time, this disease may lead to alopecia totalis, or complete hair loss.

Dermatologists treat alopecia areata with medication that may help hair regrow. If you are interested in talking with other people who have alopecia areata, NYU Langone hosts a monthly support group for people with this condition.

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. This condition causes hair to fall out in patches, sometimes circular, leading to bald spots that may get bigger over time.

The affected areas often look red or scaly, and the scalp may be itchy. Sores or blisters that ooze pus can also develop on the scalp. A child with the condition may have swollen glands in the back of the neck or a low-grade fever as a result of the immune system fighting the infection.

Dermatologists can prescribe an antifungal medication taken by mouth to eliminate the fungus. If tinea capitis is diagnosed and treated early, most children have excellent hair regrowth.

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.

Hair loss may begin so slowly that symptoms aren’t noticeable, or hair may start to fall out all at once. Other symptoms include severe itching, swelling, and red or white lesions on the scalp that may resemble a rash. This type of hair loss can occur at any age and affects men and women.

Treatment depends on the type of cicatricial alopecia causing your symptoms. Our doctors have years of experience treating people with cicatricial alopecia and can recommend a variety of treatments to help you. Types of cicatricial alopecia include:

Lichen Planopilaris

Lichen planopilaris, a type of alopecia, occurs when a common skin condition, called lichen planus, affects the scalp. Lichen planopilaris may cause a dry, flaky rash to appear on the skin that causes hair on the scalp to fall out in clumps. The scalp may also become red, irritated, and covered in small white or red itchy, painful, or burning bumps.

Lichen planopilaris is not common and affects more women than men. A doctor may prescribe medication to stop the hair loss.

Discoid Lupus Erythematosus

Discoid lupus erythematosus is a type of cutaneous lupus, an autoimmune disease that affects the skin. It can lead to inflamed sores and scarring on the ears, face, and scalp. Hair loss is one symptom of the disease. When scar tissue forms on the scalp, hair can no longer grow in that area.

Folliculitis Decalvans

Hair loss caused by folliculitis decalvans, an inflammatory disorder that leads to the destruction of hair follicles, is often accompanied by redness, swelling, and lesions on the scalp that may be itchy or contain pus, known as pustules. This type of hair loss is not reversible, but dermatologists can offer medication to control symptoms and, in some instances, stop the progression of hair loss.

Dissecting Cellulitis of the Scalp

Dissecting cellulitis of the scalp, a rare condition, causes pustules or lumps to form on the scalp. This condition may also cause scar tissue to develop, destroying hair follicles and causing hair loss. Medications may help control symptoms.

Frontal Fibrosing Alopecia

Frontal fibrosing alopecia typically occurs in a receding hairline pattern and may also result in hair loss in the eyebrows and underarms. Frontal fibrosing alopecia most commonly affects postmenopausal women. Certain medications can manage symptoms and stop the progression of the disease. The cause is unknown.

Central Centrifugal Cicatricial Alopecia

Central centrifugal cicatricial alopecia may occur as a result of hair products or styling techniques that damage hair follicles. The use of hair relaxers, blow dryers, curling irons, and hair extensions can cause central centrifugal cicatricial alopecia, as can the process of creating a permanent wave, or a “perm.”

The frequent application of oils, gels, or pomades can also cause this condition, which may be reversible if you stop using these hair products or styling techniques. Our dermatologists may recommend taking medication to help hair grow back.

Hair Shaft Abnormalities

Several types of hair shaft abnormalities can lead to hair loss. These conditions cause strands of hair to thin and weaken, making them vulnerable to breaking. The hair loss doesn’t occur in the follicle but as a result of a break somewhere along the hair shaft, which is the visible part of a hair strand. This can result in overall thinning, as well as in many small, brittle hairs.

Making simple changes to the way you style and treat your hair can reverse some hair shaft abnormalities. Other conditions may require medical intervention. Types of hair shaft abnormalities include:

Loose Anagen Syndrome

Loose anagen syndrome, which most commonly presents in young children, occurs when hair that is not firmly rooted in the follicle can be pulled out easily. Most of the time, hair falls out after it has reached an arbitrary maximum length. Children with loose anagen syndrome often cannot grow hair beyond a relatively short length. The condition more commonly affects girls with blond or brown hair.

In people who have loose anagen syndrome, hair can fall out easily—even when it’s growing. For example, hair loss may accelerate overnight because of the friction of a pillow. The cause of loose anagen syndrome is unknown, though it may be related to a disorder in the hair growth cycle that prevents hair from staying in the follicle.

There are few reliable treatments, but the condition tends to improve greatly with puberty, and some medications may result in fuller hair.

Trichotillomania

People with trichotillomania pull their hair out and find it difficult to stop. This results in hair loss on the scalp or elsewhere on the body. Hair often returns if the behavior is stopped, but hair loss can be permanent if the pulling continues for many years.

The best treatment for this condition may be psychotherapy, which might include talking with a counselor about causes of stress and why you feel the urge to pull your hair. Our doctors can refer you to a psychotherapist who specializes in this condition.

Traction Alopecia

Some hairstyles, including tight ponytails and braids, pull hair away from the scalp with such force that hair strands are damaged and fall out. Unless the hairstyle is changed, traction alopecia may lead to thinning hair or bald spots. Most of the time, hair regrows after you alter the hairstyle.

Hypotrichosis

Hypotrichosis is a rare genetic condition in which very little hair grows on the scalp and body. Babies born with this condition may have typical hair growth at first; however, their hair falls out a few months later and is replaced with sparse hair.

Many people with hypotrichosis are bald by age 25. There are few treatment options for this condition, but some medications may help to thicken or regrow hair.

Beat Hair Loss

More females are losing their hair, but there is often a simple underlying cause.

On a typical day at his hair-loss clinic, David Salinger sees people of all ages with complaints that range from dry or oily hair or scalps through to alopecia (hair loss thought to be caused by an autoimmune disorder) and balding. In recent years, however, he says he has been seeing significantly more women, many of them young and suffering from severe hair loss.

"I'm certainly seeing more young women suffering genetic hair thinning - thinning at the front and top of the scalp," Salinger, head of the Trichology Centre in Sydney and Adelaide, says. "One reason for this is the type of birth control pill they are using. Contraceptive pills that contain more of the male hormone can trigger genetic thinning. Still, that's only one reason and it isn't the major cause for all of the women I see."

Anecdotal evidence suggests that hair loss in women is on the increase, but with so many different causes, definitive data is hard to collect. There are a number of medical and nutritional areas that relate to hair and scalp problems. Of particular importance are the immune, endocrine, nervous, circulatory and digestive systems. Salinger says many people don't realise that simple nutritional imbalances are a common cause of hair loss. "Many women I see with general hair loss are suffering from an iron deficiency or have malabsorption problems," he says.

Growth Cycle

Salinger, a registered member of the International Association of Trichologists (trichology is the scientific study of hair and scalp health), explains that while hair thinning is part of the ageing process, hair loss is not. "We say that losing 70 to 80 hairs a day is normal, but having said that, everyone is different," Salinger says. "A normal amount for someone may be about 40 hairs a day, so if that suddenly doubles to 80 a day and continues, then that could be of concern and they need to see a specialist."

Tony Pearce, a trichologist and registered nurse who specialises in female hair loss, says hair loss in women is becoming more prevalent, but in most cases it can be treated relatively easily. Pearce says hair is in a constant cycle of growth, rest and renewal. It's natural to lose some hair each day, and hair grows in phases, with about one in 10 head hairs "resting" at any time. The only living part of the hair, he adds, is the root or bulb.

Treatment Options

The Australasian College of Dermatologists says the treatment for hair loss depends on the cause. In some cases the hair loss may be temporary and full regrowth will occur without treatment. The identification and treatment of reversible health conditions such as anaemia or thyroid disease can often result in complete recovery.

In other cases, hormone replacement therapy or measures to block hormone effects on the hair follicles may be used. If you have alopecia, cortisone injections into the scalp or a mixture of topical creams and lotions may be the best treatment. Antifungals or antibiotics may be required for certain infections that cause hair loss, such as tinea capitis.

As far as over-the-counter treatments are concerned, Salinger says Minoxidil 5% is the only topical non-prescription product that "can sometimes be of benefit to genetic thinning in men and women and to alopecia areata".

Getting Help

Pearce says hair-loss sufferers are not always taken seriously by GPs. He says a problem in the hair can often be the first sign of an internal problem. "Some hair-loss problems can be self-correcting and there are a lot that can be corrected through nutritional or hormonal interventions,"

Pearce says. He says many of his clients have spent thousands of dollars on products and treatments that don't work when what they needed was an iron supplement or to change their contraceptive pill. Salinger has similar stories.

He says the first thing to do if you are suffering hair loss is to find a registered trichologist, who usually works in conjunction with doctors. He says a large part of a trichologist's job is to reassure people. "Women are scared they're going to go bald. Once you show them the hair regrowing and reassure them that the problems can be fixed, usually within about three months, they feel much better," he says.

Female Hair Loss (Alopecia)

What is Alopecia?

Alopecia is simply the medical term for hair loss. Female alopecia is both common and distressing.

How I Came to Treat Alopecia 

In formal medical training, few physicians hear a word about androgenic alopecia, yet it affects 20% of women up to the forties and even more after that. I become interested in alopecia when I saw how distressing it is to women who have it. Though many of my physician colleagues do not think alopecia is worth medical attention, I disagree. Any bodily change which causes so much unhappiness is worth the effort to diagnose and treat.

Alopecia falls in between specialties. Hair is part of the skin so is included in dermatology. Yet the cause of the most common form, androgenic alopecia, is internal: the actions of hormones which are the focus of a different specialty – endocrinology. Yet few endocrinologists are trained to diagnose or treat hair loss in women. This is unfortunately because bridging the gap between specialties has made it possible to apply new knowledge about hormones to understanding and treating androgenic alopecia.

The ignorance among health professionals about the all too common and distressing condition of alopecia is truly astounding. Many doctors cannot even recognize alopecia. This is terrible for the person seeking help. Being told nothing can be done is bad enough, but not being believed is even worse. Often when I see a woman for alopecia on her first visit, she is surprised when I acknowledge that she has a problem, since so many doctors have told her nothing is wrong. Yet I cannot remember ever seeing a woman worried about alopecia who did not actually have it. With some the loss was very mild, but it was never simply their imagination. After all, each of us knows our body better than anyone else. So here are the first things that need to be said: female hair loss is real, it is distressing to all women who have it, and it can be treated!.

Why am I Losing My Hair?

Alopecia is a general term and can refer to hair loss from any cause. Indeed many diseases can cause hair loss but most are quite rare. Only two are common: alopecia areata which is due to the immune system attacking the hair follicles and androgenic alopecia, which is hormonal. 

Androgenic alopecia is extremely common. A reasonable estimate is 20% of women prior to menopause and up to 40% after that. In early stages it so mild as to escape notice by others but most affected women are only too aware that it is happening. A common abbreviation is AGA. Sometimes it is referred to as “androgenetic alopecia” to emphasize the genetic component but I do not like this term because some women with androgenic alopecia do not have it in their family.

As the name implies, androgenic alopecia is due to the effect of androgens, the family of hormones which includes testosterone. One effect of testosterone is to inactivate hair follicles on the scalp. Oddly, it makes follicles on the face and body more active. It’s not fair but the same hormone takes hair away from where it is wanted and puts it where it is not wanted. Yet this is the unfortunate truth about what testosterone does to hair follicles. These effects are very obvious and familiar in men. The much higher testosterone levels give us less hair on the scalp and more on the body than women.

As if this were not enough, testosterone also makes the skin more oily, which in turn can trigger acne. Many women with AGA have only the alopecia but some also have other unwanted effects of testosterone – hirsutism, that is, increased facial and body hair (Hormones and Unwanted Hair) and oily skin or acne. These can be part of PCOS (polycystic ovary syndrome) (PCOSupport  The Polycystic Ovarian Syndrome Association Web Site) but many women with AGA have only the alopecia without any other hormonal changes.

In my practice I’ve seen women who have been told they have PCOS but only have androgenic alopecia. But then, I’ve seen some with alopecia whose PCOS had not been diagnosed. A woman with alopecia who is overweight and/or has irregular periods, should get checked to see if she has PCOS because then additional treatments may be helpful.

Treating Female Pattern Hair Loss

Noticeable hair loss can be deeply distressing. Here are some medical treatments that may help.

About one-third of women experience hair loss (alopecia) at some time in their lives; among postmenopausal women, as many as two-thirds suffer hair thinning or bald spots. Hair loss often has a greater impact on women than on men, because it’s less socially acceptable for them. Alopecia can severely affect a woman’s emotional well-being and quality of life.

The main type of hair loss in both sexes — and the subject of this article — is androgenetic alopecia, or female (or male) pattern hair loss. In men, hair loss usually begins above the temples, and the receding hairline eventually forms a characteristic “M” shape; hair at the top of the head also thins, often progressing to baldness. In women, androgenetic alopecia begins with gradual thinning at the part line, followed by increasing diffuse hair loss radiating from the top of the head. A woman’s hairline rarely recedes, and women rarely become bald.

There are many potential causes of hair loss, including medical conditions, medications, and physical or emotional stress. If you notice unusual hair loss of any kind, it’s important to see your primary care provider or a dermatologist, to determine the cause and appropriate treatment. You may also want to ask your clinician for a referral to a therapist or support group to address emotional difficulties. Hair loss can be frustrating, but recent years have seen an increase in resources for coping with the problem.

Patterns of female hair loss

Clinicians use the Ludwig Classification to describe female pattern hair loss. Type I is minimal thinning that can be camouflaged with hair styling techniques. Type II is characterized by decreased volume and noticeable widening of the mid-line part. Type III describes diffuse thinning, with a see-through appearance on the top of the scalp.

What is androgenetic alopecia?

Almost every woman eventually develops some degree of female pattern hair loss. It can start any time after the onset of puberty, but women tend to first notice it around menopause, when hair loss typically increases. The risk rises with age, and it’s higher for women with a history of hair loss on either side of the family.

As the name suggests, androgenetic alopecia involves the action of the hormones called androgens, which are essential for normal male sexual development and have other important functions in both sexes, including sex drive and regulation of hair growth. The condition may be inherited and involve several different genes. It can also result from an underlying endocrine condition, such as overproduction of androgen or an androgen-secreting tumor on the ovary, pituitary, or adrenal gland. In either case, the alopecia is likely related to increased androgen activity. But unlike androgenetic alopecia in men, in women the precise role of androgens is harder to determine. On the chance that an androgen-secreting tumor is involved, it’s important to measure androgen levels in women with clear female pattern hair loss.

In either sex, hair loss from androgenetic alopecia occurs because of a genetically determined shortening of anagen, a hair’s growing phase, and a lengthening of the time between the shedding of a hair and the start of a new anagen phase. (See “Life cycle of a hair.”) That means it takes longer for hair to start growing back after it is shed in the course of the normal growth cycle. The hair follicle itself also changes, shrinking and producing a shorter, thinner hair shaft — a process called “follicular miniaturization.” As a result, thicker, pigmented, longer-lived “terminal” hairs are replaced by shorter, thinner, non-pigmented hairs called “vellus.”

Life cycle of a hair

Each hair develops from a follicle — a narrow pocket in the skin — and goes through three phases of growth. Anagen (A), the active growth phase, lasts two to seven years. Catagen (), the transition phase, lasts about two weeks. During this phase, the hair shaft moves upward toward the skin’s surface, and the dermal papilla (the structure that nourishes cells that give rise to hair) begins to separate from the follicle. Telogen (C), the resting phase, lasts around three months and culminates in the shedding of the hair shaft.

A clinician diagnoses female pattern hair loss by taking a medical history and examining the scalp. She or he will observe the pattern of hair loss, check for signs of inflammation or infection, and possibly order blood tests to investigate other possible causes of hair loss, including hyperthyroidism, hypothyroidism, and iron deficiency. Unless there are signs of excess androgen activity (such as menstrual irregularities, acne, and unwanted hair growth), a hormonal evaluation is usually unnecessary.

Treatment with medications

Medications are the most common treatment for female pattern hair loss. They include the following:

Minoxidil (Rogaine, generic versions). This drug was introduced as a treatment for high blood pressure, but people who took it noticed that they were growing hair in places where they had lost it. Research confirmed that a 2% solution of minoxidil applied directly to the scalp could stimulate hair growth. How it works is still not clear. Two double-blind studies of women ages 18 to 45 demonstrated its effectiveness. In one study, 13% of female minoxidil users had moderate hair growth, and 50%, minimal growth (compared with 6% and 33%, respectively, in the placebo group). In the second study, 60% of women in the minoxidil group reported new hair growth, compared with 40% in the placebo group. As a result of these studies and others, over-the-counter 2% minoxidil is FDA-approved for treating androgenetic alopecia in women.

Clearly, minoxidil is not a miracle drug. While it can produce some new growth of fine hair in some — not all — women, it can’t restore the full density of the lost hair. It’s not a quick fix, either. You won’t see results until you use the drug for two months. The effect often peaks at around four months, but it could take longer, so plan on a trial of six to 12 months. If minoxidil works for you, you’ll need to keep using it to maintain those results. If you stop, you’ll start to lose hair again.

How to use minoxidil: Be sure that your hair and scalp are dry. Using the dropper or spray pump that’s provided with the over-the-counter solution, apply it twice daily to every area where your hair is thinning. Gently massage it into the scalp with your fingers so it can reach the hair follicles. Then air-dry your hair, wash your hands thoroughly, and wash off any solution that has dripped onto your forehead or face. Don’t shampoo for at least four hours afterwards.

Some women find that the minoxidil solution leaves a deposit that dries and irritates their scalp. This irritation, called contact dermatitis, is probably caused not by the minoxidil itself, but rather by the alcohol that is included to facilitate drying. A 5% solution (available only by prescription and approved only for men) is more effective than the 2% formulation and may be prescribed off-label for women. The 5% version comes in a foam, which appears to cause less irritation than the liquid.

Side effects and concerns: Minoxidil is safe, but it can have unpleasant side effects even apart from the alcohol-related skin irritation. Sometimes the new hair differs in color and texture from surrounding hair. Another risk is hypertrichosis — excessive hair growth in the wrong places, such as the cheeks or forehead. (This problem is more likely with the stronger 5% solution.) Because the patent on Rogaine (the brand-name version of minoxidil) has expired, many generic products are available. They all contain the same amount of minoxidil, but some include additional ingredients, such as herbal extracts, which might trigger allergic reactions.

Anti-androgens. Androgen receptor–blocking drugs such as spironolactone (Aldactone) and finasteride (Propecia) are not approved for the treatment of female pattern hair loss, and there is little reliable evidence that they are effective. However, some case studies suggest that women who don’t respond to minoxidil may benefit from the addition of spironolactone. In the relatively uncommon cases where there is an excess of androgen, a clinician may prescribe 100 to 200 milligrams of an androgen receptor–blocking drug daily, together with an oral contraceptive for women of reproductive age. (A woman taking one of these drugs should not become pregnant because they can cause genital abnormalities in a male fetus.) Possible side effects include weight gain, loss of libido, depression, and fatigue.

Iron supplements. In some women, iron deficiency could be a cause of hair loss. Your clinician may test your iron level, particularly if you’re a vegetarian, have a history of anemia, or have heavy menstrual bleeding. Iron supplements are recommended if a woman’s iron level is less than 70 nanograms per milliliter. However, there’s no reliable evidence that iron supplementation is helpful for female pattern hair loss.

Hair transplantation

Hair transplantation, a procedure used in the United States since the 1950s, involves removing a strip of scalp from the back of the head and using it to fill in a bald patch. Today, 90% of hair-transplant surgeons use a technique called follicular unit transplantation, which was introduced in the mid-1990s.

During this procedure, surgeons remove a narrow strip of scalp and divide it into hundreds of tiny grafts, each containing just a few hairs. Each graft is planted in a slit in the scalp created by a blade or needle in the area of missing hair. Hair grows naturally this way, in small clusters of one to four follicles, called follicular units. As a result, the graft looks better than the larger “plugs” associated with hair transplants of yesteryear.

Follicular unit transplantation

This procedure can take several hours. First, surgeons remove an elliptical strip 3 to 4 inches long from the back of the scalp and trim the hairs short (A). The strip is then divided into 500 to 2,000 separate follicular units, each containing only a few hairs (). The units are then planted in an equivalent number of slits made in the scalp in the area of missing hair (C).

The transplanted hair will shed within two to three weeks, and new growth will start at around three months. After six to nine months, most people will have achieved 60% of new hair growth. Some surgeons prescribe minoxidil after the operation, but this approach hasn’t been studied enough to determine its effectiveness.

Side effects and concerns: Around the time new hair growth starts, some women experience folliculitis (inflammation of the follicle). This minor complication can be treated with compresses and antibiotics. A more serious hazard is shock loss, the sudden loss of hair that normally grows in the area of the transplant. Shock loss affects 30% to 50% of female hair-transplant recipients; fortunately, the loss is usually temporary, and the hair will regrow. One drawback is that there’s a finite amount of donor hair, and it may not be enough to fill in the transplant site as densely as before, especially if the area of thinning hair is large. A transplant procedure can cost from $4,000 to $15,000 and is rarely covered by insurance.

Determining the Cause of Your Hair Loss

1. Talk to your hair stylist about treatments and styling

Some chemical processes might cause hair to break off or fall off temporarily. These include bleaching and coloring, straightening, and perms. Heat from straightening irons or blow-drying can also cause hair loss.

• Hairstyles that pull your hair tightly can cause "traction alopecia," in which follicles are damaged over time. If you feel scalp pain, avoid pulling your hair back into tight ponytails or other styles that pull the hair.

2. Take family history into consideration

Ask your parents whether there's a history of hair loss in your family. The most common cause of hair loss in adults — male or female pattern baldness — is genetic. However, a combination of genetics and hormones can start this sort of hair loss in your mid-teen years.

• Recent studies show that genetic hair loss can be inherited from either parent in both boys and girls.

3. Keep track of excessive shedding

Some amount of shedding — about 50 to 100 hairs per day — is completely normal. However, stress or traumatic events (accidents, surgery, illness) can cause excessive shedding. Normally, excessive shedding goes back to normal within six to nine months, but constant stress can cause it to progress to permanent hair loss.

4. Be cautious about pulling out your hair

Teenagers often play with their hair absent-mindedly, twirling or tugging on it. In some cases, this may be a symptom of a disorder called "trichotillomania," in which people pull out their hair when nervous or distracted. Though the behavior is usually unconscious, it leaves sufferers with bald patches. #*The disorder is often caused by stress. See a therapist or a hair and scalp specialist called a "trichologist" for proper diagnosis and treatment.

5. See your family doctor or dermatologist about medical conditions

There are many illnesses and conditions that could cause hair loss. Hormonal conditions like uncontrolled diabetes, thyroid disease, or polycystic ovary syndrome can interfere with hair production. Those with lupus can also experience hair loss.

• Eating disorders like anorexia or bulimia can starve the body of essential proteins, vitamins, and minerals needed for hair growth. Some vegetarian teens also lose hair if they don’t get enough protein from non-meat sources.
• Athletes are at a higher risk for hair loss because they’re more likely to develop iron-deficiency anemia. Anemia can then result in hair loss.
• One cause of patchy hair loss, often with scaling and broken hairs, is ringworm of the scalp, called tinea capitis. It is not very common in teens, but it can occur. This is caused by a fungal infection and is treated with oral medications and special shampoos.

6. Check for small, round bald patches

One or more of these patches on your scalp may point to a skin disease called "alopecia areata" that causes hair loss. It's an autoimmune disorder in which your own immune system damages hair follicles. Luckily, it can be treated, and hair usually regrows within a year. Still, some sufferers lose their hair repeatedly or even permanently.

• If unchecked, alopecia areata can sometimes progress to full baldness or even complete loss of all body hair, though this is rare. See a dermatologist for a proper diagnosis, which may involve simple examination of hair under a microscope or may call for a skin biopsy.
• The condition is not contagious.

7. Speak with your doctor about medications

Chemotherapy for cancer is a medical treatment particularly well-known for causing hair loss. However, many prescription drugs — including some used to treat acne, bipolar disorder, and ADHD — list hair loss as a side effect. Diet pills that contain amphetamines can also cause hair loss. Show your doctor a detailed list of all current medications, both prescription and over-the-counter, to see if they might be causing your problem.