Hypertrichosis and Its Causes and Treatments

Hypertrichosis describes abnormal, often excessive hair growth anywhere on the body. It can affect both males and females. In severe cases, the whole body may be covered in thick hair. It is sometimes also called "werewolf syndrome." Hypertrichosis differs from hirsutism, which is a condition that causes females to experience abnormal hair growth in a male-like pattern.

There are different forms of hypertrichosis. A person can be born with hypertrichosis (the congenital form) or get it later in life as a result of another medical condition (the acquired form).

This article discusses hypertrichosis and its causes. It also looks at some of the ways the condition is treated.

What Is Hypertrichosis?

Hypertrichosis is a condition that causes abnormal hair growth. People with hypertrichosis may grow excessive amounts of hair anywhere on the body. The condition can affect males and females.

In rare cases, a person can be born with this condition. This is called congenital hypertrichosis. There are fewer than 50 documented cases of congenital hypertrichosis.

Hypertrichosis can cause abnormal hair growth ranging from small patches to full-body coverage. A person with severe hypertrichosis may 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 treat even severe forms of the condition.

Hypertrichosis Symptoms

Several subtypes of hypertrichosis determine what it looks like and what treatment options are available. Each type 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. 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 the cheeks and arms/legs of children 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.

Congenital Hypertrichosis

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."

Acquired Hypertrichosis

Certain medical conditions can cause 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.

Other Symptoms

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

What Causes Hypertrichosis?

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 may respond to the loss of insulating body fat by growing a fine layer of lanugo.

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

• HIV/AIDS
• 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

How Hypertrichosis Is Diagnosed

Hypertrichosis is very rare. Based on the diagnosed cases, it seems to affect both biological sexes equally.

If the abnormal hair growth is severe and begins in childhood, a diagnosis of congenital hypertrichosis is fairly simple. If there is also a family history of similar symptoms, this can also help suggest the diagnosis.

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 growth patterns are consistent with hypertrichosis.

More effort may go into finding the cause and appropriate course of treatment in cases of acquired hypertrichosis.

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 an inherited condition such as Cornelia de Lange syndrome or Rubinstein-Taybi syndrome, genetic tests may be required.

Treatment Options

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, managing the underlying medical disorder is the first-line treatment.

When hypertrichosis is caused by a medication, adjusting the dose or stopping the medication may be enough to resolve the hair growth. Certain medications can also prevent or slow down hair growth. Topical medications called depilatory creams can also be prescribed.

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. It 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, electrolysis treatments can be painful and expensive.

People who have widespread hypertrichosis may need to use more than one hair removal method. They may also 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 can usually find a hair removal method that suits their needs and preferences, though it may take some trial and error.

Coping With Hypertrichosis

People with hypertrichosis may experience anxiety, depression, low self-esteem, and poor body image as a result of their condition.

People who have the congenital form 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 their age, so they may be more susceptible to low self-esteem, poor body image, and depression associated with their condition.

Summary

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.

There is no cure for the condition but depending on the cause, there are different ways to manage it. Addressing the underlying cause or changing medications is usually enough to resolve the hair growth.

For people who are born with hypertrichosis, especially severe forms, there isn’t typically a one-time treatment, though hair removal methods like waxing and electrolysis can help.