What Is Hypertrichosis?

  • Rajni Sarma MBBS, MD from North-Eastern Hill University, India


The famous Disney fairytale “Beauty and the Beast” may have had a real-life inspiration in the story of the beast-like man, Petrus Gonsalves. He was known as a wild man and treated less than a human all his life because there was little to no awareness of the medical condition he had. He was neither a beast nor a wild man. He just had hypertrichosis.

Hypertrichosis is excessive body hair growth beyond the normal variation seen in people of similar age, sex, and race.1 This hair growth is not dependent on androgens. Hypertrichosis is different from hirsutism as hirsutism refers to excessive hair growth with male pattern distribution seen in women.2

Hypertrichosis, also known as werewolf syndrome, has affected many people over the years. Because of the poor knowledge surrounding the condition, most people with hypertrichosis were either working for circuses or passed around from one royal family to another as “human pets.” However, with increasing scientific research, more light has been shed on this condition.

Characteristics of hypertrichosis 

Hypertrichosis is characterized by excessive body hair growth, which is not influenced by androgens. There are variations in appearance depending on the hair type affected and the body site affected.

There are three types of body hair seen in an individual, which are:

Lanugo hair

It is seen normally in a baby still in the womb. It is described as light-coloured and delicate and can be many centimetres long. It usually covers the entire body of the unborn baby. 

Lanugo hair is exchanged for vellus and terminal hair when the baby in the womb is about 8 months. Within a few weeks after birth, lanugo hair is completely replaced by vellus and terminal hair.

Vellus hair

It is short and light-coloured, the hair type that covers the body. 

Terminal hair

It is the coarse kind seen on the head, armpit, and pubic regions. In men, it can be found on the face, chest and back in response to the surge of male hormones during and after puberty.

However, in hypertrichosis, there could be overgrowth of one or more of these hair groups. Variations in length and density are commonly seen in this disorder. The parts of the body affected also vary in different subtypes of hypertrichosis. Sometimes, only a singular part of the body is affected, such as the elbows or the back. In other subtypes, the entire body is affected.

Types of hypertrichosis

There are two major types of hypertrichoses: congenital and acquired. Congenital hypertrichosis usually presents from birth, while acquired hypertrichosis develops later in life.

These two major types are further divided into two subtypes: generalized and localized. A generalized subtype affects the entire body, while a localized subtype affects a specific part of the body.

Therefore, hypertrichosis could be grouped into four major types, these are:3

  • Congenital Generalized Hypertrichosis (CGH)
  • Congenital Localized Hypertrichosis (CLH)
  • Acquired Generalized Hypertrichosis (AGH)
  • Acquired Localized hypertrichosis (ALH)

Congenital generalized hypertrichosis 

It appears in two distinct forms:

Congenital hypertrichosis lanuginosa: As the name suggests, it is a generalized excess growth of lanugo-type hair. This form of CGH looks rather dramatic because of the hair type affected. Hair strands can grow up to 10cm long, giving off a werewolf appearance.2

Congenital hypertrichosis universalis

This has a similar appearance to the first form discussed, but the hair type affected is different. In this subtype, there is excessive growth of terminal-type hair seen all over the body.2

Acquired generalized hypertrichosis

 It also has two distinct forms. The first form is a slow overgrowth of terminal-type hair. The second is just like congenital hypertrichosis lanuginosa; there is excess growth of lanugo-type hair. It is called acquired hypertrichosis lanuguinosa. This form is associated with cancers and is sometimes the telltale sign that someone has cancer.2

Causes of hypertrichosis

The causes of hypertrichosis differ depending on the type of hypertrichosis present. The cause of congenital hypertrichosis is unclear, but it has been related to several factors, which include changes in the genes, inheritance from parents, association with other diseases, and effects of medications.

Many genes have been implicated in congenital hypertrichosis. It is theorized that there is a defect in some group of genes that causes this excess hair growth. Usually, these gene defects affect other parts of the body such as the face, bones, head, and eyes. Hypertrichosis occurs in this case in conjunction with other illnesses or deformities.3

Sometimes, congenital hypertrichosis is inherited from the parents. This also has to do with the genes, but in this case, the defective gene comes from the parent(s) and is inherited by the child. The parents of the child may or may not have symptoms. It all depends on the kind of genetic inheritance taking place.3

Medications have also been implicated in congenital hypertrichosis. Minoxidil is a medication that can cause hair growth, and if minoxidil is taken by a pregnant woman, it could cause congenital hypertrichosis in her child.2

Acquired hypertrichosis, on the other hand, has more to do with medications, illnesses, or traumatic incidents than with gene defects or inheritance.  Most of the causes of acquired hypertrichosis are medications. 

Some common medications known to cause acquired hypertrichosis are minoxidil, streptomycin, phenytoin, and acetazolamide. This is by no means an exhaustive list as there are many other medications which could cause hypertrichosis.2

A particular subtype of acquired hypertrichosis has been observed to occur with specific cancers. Sometimes, it occurs before the cancer is diagnosed and helps signal the presence of the cancer. The cancers associated with this subtype are cancers of the breast, lungs, and colon.2

Medical conditions such as traumatic brain injuries, malnutrition, juvenile hypothyroidism, juvenile dermatomyositis, and advanced HIV infection have been seen to cause acquired generalized hypertrichosis. In some localized forms of hypertrichosis, injuries have been implicated. These injuries could be from vaccination sites or from repeated trauma seen, for instance, in weightlifters. In these cases, hypertrichosis will only affect the injury site.2

Diagnosis and evaluation 

To diagnose hypertrichosis, a doctor would ask specific questions and observe the individual to know what type of hypertrichosis is present. This is done before any major tests are carried out because some of the subtypes of hypertrichosis do not need tests to be diagnosed.

First, a doctor would find out if the disorder is congenital or acquired. This is done by asking about the onset of the symptoms. Once that is figured out, the next thing would be to examine the hair type affected. The site affected on the individual would also be taken into consideration as these two factors – hair type and site; would help the doctor to identify what subtype of hypertrichosis the individual has.

Once the subtype is known, the doctor will ask questions specific to that form of hypertrichosis with the aim of finding factors associated with that specific subtype. This is important because some forms of hypertrichosis are reversible if there is a reversible cause, for instance, a medication. Other subtypes could be a signal for cancer yet to be diagnosed or could be related to inherited defective genes that may be associated with other medical conditions.  This is why recognizing the associated factors of different forms of hypertrichosis is vital.

Investigations are done for some subtypes. Gene studies may be done for congenital hypertrichosis suspected to be caused by defective genes. If a person has acquired hypertrichosis lanuginosa, they would be screened for cancers.

Treatment and management 

The treatment for hypertrichosis is cosmetic because that is usually a major concern for those who have this disorder. Hypertrichosis causes severe emotional distress for those affected and their family members. In adults, and most importantly, children, it can cause social isolation, which affects the mental and social development of the affected individual. Treatment includes:1,2,3

Cosmetic procedures

These include shaving, waxing, bleaching and the use of chemical hair removal substances. Bleaching is done to change the colour of the overgrown hairs and make them less prominent. Chemical hair removal creams can be applied to the skin to remove hairs. This is called depilation. 

Sometimes, an electric needle is inserted just under the skin for more effective removal of the hair follicles, but all the above measures are very irritating to the skin. Shaving is the treatment of choice for babies and young children who have hypertrichosis.1

Electrolytic destruction

It is done using special lasers and light sources. This is said to be the most effective way of removing hair follicles, but hair growth still occurs in 1 in every 3 patients who get this treatment.1,3 Multiple treatments might be required, and this can also cause skin irritation.

Discontinuation of suspected drugs

If hypertrichosis is caused by certain medications, stopping or reducing the dose of the offending medication is part of the management.

Emotional support

Psychological support cannot be overemphasized with this condition because of the terrible impact this condition can have on the lives of those affected. Encouragement from family members, support groups and counselling are important in helping the affected individual live a healthy and normal life.


The prognosis depends on the type of hypertrichosis present. For congenital types, the disorder is present for life, while acquired types might be reversible depending on their causes.

Acquired hypertrichosis lanuguinosa has a poor prognosis as it usually occurs with cancer. Some congenital types may also be associated with other diseases, causing a poor prognosis as well.


Hypertrichosis is a disorder causing excessive hair growth in relation to what is normal for age, sex, and race. The nature of the disorder makes for a significant psychological effect on the affected individuals in addition to other related diseases they could suffer from. The prognosis might be poor, but as long as science keeps evolving, there is hope for a more definitive treatment.


  1. Baumeister FA, Schwarz HP, Stengel-Rutkowski S. Childhood hypertrichosis: diagnosis and management. Arch Dis Child [Internet]. 1995 [cited 2024 Jan 11];72(5):457–9. Available from: http://dx.doi.org/10.1136/adc.72.5.457
  2. Saleh D, Yarrarapu SNS, Cook C. Hypertrichosis. StatPearls Publishing; 2023. Available from:  http://www.ncbi.nlm.nih.gov/books/NBK534854/.
  3. Pavone P, Praticò AD, Falsaperla R, Ruggieri M, Zollino M, Corsello G, et al. Congenital generalized hypertrichosis: the skin as a clue to complex malformation syndromes. Ital J Pediatr [Internet]. 2015;41(1). Available from: http://dx.doi.org/10.1186/s13052-015-0161-3
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

Get our health newsletter

Get daily health and wellness advice from our medical team.
Your privacy is important to us. Any information you provide to this website may be placed by us on our servers. If you do not agree do not provide the information.

Oghenefejiro Adebola Anugom

Oghenefejiro Anugom MBBS, Delta State University, Abraka, Nigeria

Fejiro is a medical doctor currently working as a GP trainee with the NHS. She has always been interested in writing, especially medical writing as she believes an enlightened public would lead to better health outcomes. She currently lives in the UK with her husband and enjoys travelling to new places.

my.klarity.health presents all health information in line with our terms and conditions. It is essential to understand that the medical information available on our platform is not intended to substitute the relationship between a patient and their physician or doctor, as well as any medical guidance they offer. Always consult with a healthcare professional before making any decisions based on the information found on our website.
Klarity is a citizen-centric health data management platform that enables citizens to securely access, control and share their own health data. Klarity Health Library aims to provide clear and evidence-based health and wellness related informative articles. 
Klarity / Managed Self Ltd
Alum House
5 Alum Chine Road
Westbourne Bournemouth BH4 8DT
VAT Number: 362 5758 74
Company Number: 10696687

Phone Number:

 +44 20 3239 9818