An Overview of Hypertrichosis

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Hypertrichosis results in abnormal, often excessive, hair growth. Almost any part of the body can be affected and in severe cases, the whole body is covered in thick hair. There are different forms of the condition: a person can be born with hypertrichosis (congenital form) or get it later in life as a result of another medical condition (acquired form). There are also several subtypes of the condition which determine what it looks like and what treatment options are available.

Congenital forms of hypertrichosis are extremely rare—fewer than 50 documented cases have been recorded —but all forms of the condition have perplexed medical professionals throughout history. Individual cases were documented as early as the Middle Ages. Several instances of hypertrichosis in families were recorded throughout Europe, Asia, and North America well into the 20th century. At least one case of congenital hypertrichosis has been diagnosed since the mid-2000s.

Alice Doherty as a teenager.
Alice Doherty, the only person diagnosed with congenital hypertrichosis lanuginosa in the United States (credit: Wiki Commons).

Hypertrichosis can range from small patches of abnormal hair growth to full-body coverage. A person with severe hypertrichosis may literally be covered head to toe by the hair, including their face and hands. Historically, the striking appearance characteristic of severe hypertrichosis resulted in people referring to the condition as “werewolf syndrome.”

Research on hypertrichosis is somewhat limited because so few cases have been diagnosed; some studies are nearly a century old. While the cause may be elusive, cosmetic technology, especially hair removal, can offer treatment for even severe forms of the condition.


The symptoms of hypertrichosis will depend on which form and type a person has. Each type of hypertrichosis is characterized by a certain kind of hair growth: lanugo, vellus, and terminal.

  • Lanugo is a soft, fine, light-colored layer of hair that covers a fetus in the womb. All newborns are born with lanugo and it may develop in adults due to certain medical conditions. It’s not as visually obvious as other types of hair growth.
  • Vellus hair is typically blonde, thin, and grows on cheeks and arms/legs of kids before thick dark terminal hair grows.
  • Terminal hair growth is thicker, longer, and darker than the other forms and is the type that grows on your head. The androgen released during puberty transforms vellus hair into terminal. Of the three types of hair growth, terminal is the most noticeable.  

A person can either be born with the condition or acquire it later in life. There are three types of hypertrichosis a person can be born with.

  • Congenital hypertrichosis lanuginosa: In this form of the condition, this fine layer of hair present during the fetus stage doesn’t go away after the baby is born and instead, continues to grow.
  • Congenital hypertrichosis terminalis: This is the characteristic “werewolf syndrome” form of the condition where a person experiences abnormal—and often stark—hair growth over large areas of their body. As opposed to lanugo, the hair is typically dark and may be quite thick.
  • Nevoid hypertrichosis: This form may also occur later in life but is usually present at birth. It's a less severe form of hypertrichosis where the abnormal hair growth is limited to relatively small, isolated patches. One of the more common examples is a unibrow.

Certain medical conditions can also result in hypertrichosis, including:

  • Acquired hypertrichosis: Depending on the cause, this form can be relatively mild or as severe as congenital forms. A person with acquired hypertrichosis can experience two kinds of hair growth: vellus or terminal.
  • Hirsutism: This type of abnormal hair growth occurs when thickness and patterns of hair growth that typically occur in the male body, such as facial hair, occur in a female body. The condition is characterized by the growth of dark, coarse, hair on specific areas of the body such as the upper lip (in the pattern of a mustache), the chest, and the back.

In addition to abnormal amounts or patterns of hair growth, many people with hypertrichosis have problems with their oral health. If you have the congenital form of the condition you’re more likely to have a condition called gingival hyperplasia which causes enlarged gums that may be prone to bleeding. Teeth of babies born with hypertrichosis and gingival hyperplasia may come in late or fail to come in at all.

Congenital hypertrichosis that’s accompanied by other bodily abnormalities, such as poor dental health, is sometimes referred to as hypertrichosis universalis congenita, or Ambras syndrome.


Researchers aren’t exactly sure why and how the various forms of hypertrichosis occur, but there have been several studies exploring the possibility of a genetic cause.

In 2011, a team of researchers implicated a specific gene that controls hair growth during fetal development. Since some cases have occurred within families, it seems likely that genes are involved.

When people develop an acquired form of hypertrichosis later in life, the cause is much easier to identify. For example, if a person with anorexia nervosa becomes severely underweight, the body often responds to the loss of insulating body fat by growing a fine layer of lanugo to keep warm.

Several health conditions are known to potentially cause abnormal hair growth, including:

  • Acromegaly 
  • Lichen simplex 
  • Dermatomyositis 
  • POEMS syndrome
  • Porphyria cutanea tarda 
  • Juvenile hypothyroidism 
  • Eating disorders and malnutrition
  • Cancer (most often lung, colon, and breast)
  • Change in blood flow or increased skin friction over certain parts of the body (such as from wearing a cast if you break your arm). 

Several classes of drugs have been associated with acquired hypertrichosis, including steroids, anticonvulsants, vasodilators, anti-inflammatory medications, and photosensitizers.  

Medications that may cause abnormal hair growth include:

  • Chelators 
  • Minoxidil
  • Fenoterol
  • Phenytoin 
  • Cyclosporine 
  • Streptomycin
  • Corticosteroids
  • EGFR inhibitors
  • Interferon-alpha
  • Methoxypsoralen
  • Hexachlorobenzene

Hirsutism is specifically related to androgenic hormone imbalances. The condition is typically seen in people with polycystic ovary syndrome (PCOS). It can also occur in people who have adrenal, pituitary, or thyroid conditions.

The condition may also occur during periods of fluctuating androgen levels such as pregnancy and menopause. Changes in hormone levels caused by certain medications, such as steroids and oral contraceptives, can also lead to hirsutism.  


Hypertrichosis is very rare. Based on the diagnosed cases, it seems to affect both biological sexes equally (with the exception of hirsutism which only occurs in females).

If the abnormal patterns of hair growth are quite severe and begin in childhood, it can be fairly easy to make a diagnosis of congenital hypertrichosis—particularly if there is also a family history of similar symptoms.

In more subtle cases, doctors can use a microscope to look at samples of a person’s hair to see if the excessive and abnormal patterns of growth are consistent with hypertrichosis.

In cases of acquired hypertrichosis that occur later in life, it may require more work to figure out the cause and determine the appropriate course of treatment.

Blood tests can be useful to identify abnormal testosterone levels or other hormonal imbalances. If a doctor suspects an underlying health condition like thyroid disease or cancer, imaging tests like ultrasounds may be necessary. Pelvic and transvaginal ultrasounds can be helpful if looking for signs of PCOS, which is a common cause of hirsutism.

If doctors suspect hypertrichosis signals an underlying inherited condition such as Cornelia de Lange syndrome or Rubinstein-Taybi syndrome, genetic tests may be needed to look for specific mutations used to make a diagnosis.


There is no cure for hypertrichosis, but knowing whether it's congenital or acquired can help doctors choose a treatment. If abnormal hair growth is due to another condition such as PCOS or thyroid disease, managing the underlying medical disorder is the first-line treatment.

If hypertrichosis is being caused by a medication, adjusting the dose or stopping the medication may be enough to resolve the hair growth. It may also be possible to give a person a medication to prevent or slow down hair growth. Topical medications called depilatory creams can also be prescribed. For people with hirsutism, hormonal medications may be effective.

People with severe hypertrichosis may find it difficult, overwhelming, expensive, and painful to have abnormal hair growth routinely plucked, shaved, bleached, or waxed. Even for people who do not have abnormal hair growth, these measures are only temporary. They usually last, at most, a few weeks.

Laser hair removal is a longer-lasting option but typically requires more than one session, can be expensive, and may not work well on certain types of hair. Electrolysis is the FDA-approved treatment for permanent hair removal. While the method does remove the hair permanently, electrology treatments can be painful and expensive.

People who have widespread hypertrichosis may need to use more than one hair removal method and may need to use them repeatedly for treatment to be effective. The hair on one area of the body may not be removed well—or safely—using certain methods. Certain areas of the body may also be too sensitive for some methods or more likely to become infected.

Since there have been so few cases of hypertrichosis diagnosed, the research on treatments for severe forms of the condition is limited. People with milder forms and hirsutism can usually find a hair removal method that suits their needs and preferences, though it may take some trial and error.


People with hypertrichosis may experience anxiety, depression, low self-esteem, and poor body image as a result of their condition. If they have a form that began in childhood, they may have endured many years of bullying by their peers. As a result, people with hypertrichosis can feel insecure around and isolated by those who do not have the condition (even friends and family).

Hypertrichosis can have a detrimental effect on a person's social life. People of any age with the condition, but particularly children, may resist activities such as swimming or changing in the school locker room due to anxiety about their appearance. The anxiety may result in these children missing out on special events with their peers both at school and in the community, such as birthday parties and team sports.

Teenagers with hypertrichosis are already dealing with hormonal and social changes that come with the age, so they may be more susceptible to low-self esteem, poor body image, and depression associated with their condition.

Young people with hypertrichosis and their families can benefit from medical, social, and mental health resources. Support groups, therapy, and antidepressant medications can be very helpful for people with any form of hypertrichosis if they find the experience of living with the condition distressing but may be especially important for helping children and young adults learn coping skills they can use throughout their life.

A Word From Verywell 

Hypertrichosis is a rare disorder that causes abnormal, sometimes excessive, hair growth all over the body. People can be born with the condition or develop it later in life due to a medical disorder or certain medications. Little is understood about how and why the condition develops because there have only been about 50 documented cases since the Middle Ages. Since the disorder can occur in families, genetics likely play a role in some forms of hypertrichosis.

There is no cure for the condition but depending on the cause, there are different ways to manage it. The first-line treatment is to figure out if there is an underlying medical cause for abnormal hair growth, such as PCOS or a medication. Addressing these causes by treating the disorder or changing medications is usually enough to resolve the hair growth in these cases. For people who are born with hypertrichosis, especially severe forms, there isn’t typically a one-time treatment. Some people with the condition choose to regularly remove excess hair through shaving or waxing, and others use permanent methods like electrolysis. While the results of these methods last longer they can be painful and expensive.

Emotional support, especially for children with the condition, is very important as people with hypertrichosis may experience depression and anxiety as a result of their condition. Support groups, therapy, and medication can help people with hypertrichosis cope with the challenges of living with the condition.

6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Abby Norman
Abby Norman is a freelance science writer and medical editor. She is also the author of "Ask Me About My Uterus: A Quest to Make Doctors Believe in Women's Pain."