Definition: Hypertrichosis describes hair growth on the body in an amount considered abnormal; extensive cases of hypertrichosis have informally been called werewolf syndrome. [1]

Types of hypertrichosis

There are two distinct types of hypertrichosis: generalized hypertrichosis, which occurs over the entire body, and localized hypertrichosis, which is restricted to a certain area. Hypertrichosis is either congenital (present at birth) or acquired later in life. [2]

Congenital Forms

Congenital forms of hypertrichosis are caused by genetic mutations. Congenital hypertrichosis forms are extremely rare unlike acquired forms and are always present at birth. 

Hypertrichosis lanuginosa – Congenital hypertrichosis lanuginosa is noticeable at birth with the infant completely covered in thin lanugo hair. In normal circumstances, lanugo hair is shed before birth and replaced by vellus hair; however, in an individual suffering from congenital hypertrichosis lanuginosa, the lanugo hair remains after birth. The palms of the hands, soles of the feet, and mucous membranes are not affected. As the person ages, the lanugo hair may thin leaving only limited areas of hypertrichosis. [1]

Generalized hypertrichosisCongenital generalized hypertrichosis causes males to exhibit excessive facial and upper body hair, whereas women exhibit less severe asymmetrical hair distribution. The palms, soles, and mucous membranes are not affected. [1]

Terminal hypertrichosisCongenital terminal hypertrichosis is characterized by the presence of fully pigmented terminal hair that covers the entire body. This condition is usually accompanied by gingival hyperplasia.  This form is most responsible for the term “Werewolf Syndrome” because of the thick dark hair that appears.  Sufferers of this condition are sometimes performers at circuses because of their unusual appearance.

Circumscribed hypertrichosis – Congenital circumscribed hypertrichosis is associated with the presence of thick vellus hair on the upper extremities. Circumscribed signifies that this type of hypertrichosis is restricted to certain parts of the body, in this case, the extrasensory surfaces of the upper extremities. Hairy Elbow Syndrome, a type of congenital circumscribed hypertrichosis, shows excessive growth on and around the elbows. This type of hypertrichosis is present at birth, becoming more prominent during aging, only to regress at puberty. [3] 

Acquired Hypertrichosis

Acquired hypertrichosis appears after birth. There are multiple causes, including the side effects of drugs, associations with cancer, and possible links with eating disorders. Acquired forms of hypertrichosis can usually be reduced with various treatments.

Hypertrichosis lanuginosa – Acquired hypertrichosis lanuginosa is characterized by rapid growth of lanugo hair, particularly on the face. Hair also appears on the trunk and armpits, while palms and soles are unaffected. The excess hair is commonly referred to as malignant down. This hair is very fine and unpigmented. [4]

Generalized hypertrichosis – Acquired generalized hypertrichosis commonly affects the cheeks, upper lip, and chin. This form also affects the forearms and legs; however, it is less common in these areas. Another deformity associated with acquired generalized hypertrichosis is multiple hairs occupying the same follicle. It may also include abnormal hair growth patterns as what happens to the eyelashes in a condition known as trichiasis. Oral minoxidil treatments for hypertension are known to cause this condition. Topical minoxidil used for alopecia causes hair growth in the areas it is applied to, however this hair disappears shortly after discontinuing the use of topical minoxidil.[4] 

Patterned hypertrichosis – Acquired patterned hypertrichosis is an increase in hair growth in a pattern formation. It is similar to acquired generalized hypertrichosis and is a sign of internal malignancy. [5] 


There is no cure for any congenital forms of hypertrichosis. The treatment for acquired hypertrichosis is based on attempting to address the underlying cause. Acquired forms of hypertrichosis have a variety of sources, and are usually treated by removing the factor causing hypertrichosis, e.g. a medication with undesired side-effects. All hypertrichosis, congenital or acquired, can be reduced through hair removal.

Permanent Solution – Laser Hair Removal

Laser hair removal systems are currently widely used for long-term hair removal. The need to have a fast and non-invasive treatment method led to the development of this treatment. 

All laser treatment systems use the principle of selective photothermolysis where a selected chromophore is targeted by the laser to produce the heat that destroys the follicle. Therefore deep penetrating wavelengths in the range of 600 – 1100 nano meters (nm) are used. Care is taken to limit skin damage by restricting damage to the target area. This is done by ensuring enough laser absorption by the target and using a pulse rate shorter than the thermal relaxation time of the target. [6]

Due to the fact that a laser targets melanin, the more melanin an individual has in his/her hair, the more effective a laser will be. Therefore, someone with gray, red, or blonde hair is not as good a candidate for laser hair removal as one with darker hair. [7]

Compared to electrolysis, laser treatments are faster, less painful, less operator dependent and perhaps more effective. However, unlike in electrolysis, single hair or a small group of hairs cannot be targeted by laser. [7]

Most adverse effects are temporary and include commonly erythema and perifollicular edema and less frequently crusting and vesiculation of the site, hypopigmentation and hyperpigmentation. Their effect can be lessened by lightening the skin, avoiding the sun before and after treatment and cooling the skin during treatment. [6]

Temporary Treatments

Temporary hair removal may last from several hours to several weeks, depending on the method used. These procedures are purely cosmetic. Depilation methods remove hair to the level of the skin. These techniques produce results that last several hours to several days. Trimming, shaving, and depilatories are examples of depilation methods. Epilation methods remove the entire hair from the root, the results lasting several days to several weeks. Plucking, electrology, waxing, sugaring, threading are examples of epilation methods. [8]


  1. Wendelin, D.; Pope, D.; Mallory, S. (2003). “Hypertrichosis”. Journal of the American Academy of Dermatology 48: 161–179.
  2. Sutton, Richard L. (1916). Diseases of The Skin. St. Louis: C.V. Mosby Company. pp. 408,705. http://books.google.com/books?id=5PBY5xtLCWIC&pg=PA705&dq=Hypertrichosis&ei=3L2vSt9sktjKBMSauY8F#v=onepage&q=Hypertrichosis&f=false. Retrieved November 29, 2009.
  3. Escalonilla, P; Aguilar; Gallego; Piqué; Fariña; Requena (1996). “A new case of hairy elbows syndrome (Hypertrichosis cubiti)”. Pediatric dermatology 13 (4): 303–5. PMID 8844750.
  4. James, William; Berger, Timothy; Elston, Dirk (2005), Andrews Diseases of the Skin: Clinical Dermatology (10 ed.), Saunders, pp. 769
  5. Laser Hair Removal. The Patient’s Guide. http://www.hairremovaljournal.org
  6. Ngan, Vanessa (June 15, 2009). “Epilation”. DermNet NZ. New Zealand Dermatological Society Incorporated. http://dermnetnz.org/procedures/epilation.html. Retrieved November 29, 2009.