Hypertrichosis (Excessive Hair Growth): Causes, Types, Symptoms & Treatment

Hypertrichosis is a rare condition that causes excessive hair growth beyond what is expected for a person’s age, sex, and body area. The extra hair can appear on a small part of the body or cover large areas. It can also involve fine, light hair or thick, dark hair.

Although hypertrichosis often affects appearance rather than overall health, new or rapidly increasing hair growth deserves medical attention. In some cases, medications, systemic illnesses, or other underlying conditions can trigger the problem.

What Is Hypertrichosis?

Hypertrichosis means excessive hair growth anywhere on the body. Both men and women can develop the condition.

The hair may:

• Grow in a small, localized patch

• Cover several areas of the body

• Appear as fine, soft hair

• Become thick, long, and pigmented

• Develop at birth or later in life

Doctors generally classify hypertrichosis as either congenital or acquired, depending on when it begins.

Hypertrichosis vs. Hirsutism

People often use the terms hypertrichosis and hirsutism interchangeably. However, they describe different patterns of excessive hair growth.

In simple terms, hypertrichosis means too much hair growth, while hirsutism describes excessive male-pattern hair growth in women.

Types of Hypertrichosis

Doctors can classify hypertrichosis according to when it develops and how widely it affects the body.

1. Congenital Hypertrichosis

Congenital hypertrichosis is present at birth. Genetic changes can cause some rare forms of this condition.

Congenital Hypertrichosis Lanuginosa

This extremely rare form causes persistent growth of lanugo hair. Lanugo normally consists of fine, soft hair that covers a fetus before birth and usually disappears before or around birth.

In congenital hypertrichosis lanuginosa, this fine hair can continue to grow after birth.

Congenital Hypertrichosis Terminalis

This form causes widespread growth of thick, pigmented terminal hair. Some people may also have associated gum enlargement and dental abnormalities.

2. Naevoid Hypertrichosis

Naevoid hypertrichosis produces a clearly defined patch of excessive hair growth.

For example, a person may develop a single unusually hairy patch on the body. A patch of dense hair over the lower back, sometimes called a faun-tail sign, can occasionally signal an underlying spinal abnormality.

3. Acquired Hypertrichosis

Acquired hypertrichosis develops after birth.

It can affect a specific area or become generalized. Several factors can trigger it, including certain medications, systemic illnesses, nutritional problems, and repeated irritation or friction of the skin.

What Causes Hypertrichosis?

Several factors can contribute to excessive hair growth.

Genetic Changes

Some congenital forms result from rare genetic changes. These conditions may run in families, although some genetic changes can occur spontaneously.

Medications

Certain medications can stimulate excessive hair growth. Commonly reported examples include:

• Minoxidil

• Phenytoin

• Cyclosporine

• Bimatoprost

• Latanoprost

• Some corticosteroids

• Certain other medications

Therefore, if excessive hair growth starts after you begin a medication, discuss the change with your healthcare professional. Do not stop a prescribed medicine without medical advice.

Nutritional Problems

Severe undernutrition and certain eating disorders can sometimes cause acquired hypertrichosis. For this reason, unexplained hair growth accompanied by significant nutritional problems deserves medical evaluation.

Systemic Illnesses

Certain medical conditions can also contribute to excessive hair growth. Reported associations include:

• Porphyria

• Dermatomyositis

• Some neurological disorders

• Advanced HIV infection

• Severe nutritional disorders

However, these conditions do not explain every case of hypertrichosis. A healthcare professional should assess the complete clinical picture.

Repeated Skin Irritation

Repeated rubbing, scratching, inflammation, or trauma can sometimes increase hair growth in a particular area.

For example, localized hair growth may become noticeable after removing a cast from an injured limb.

Rare Cancer-Related Causes

Rarely, rapidly developing widespread fine hair growth can occur as a paraneoplastic syndrome, meaning it is associated with an underlying cancer.

This type of hair growth can appear suddenly and may affect areas that normally have little hair. Fortunately, this cause is uncommon. Still, sudden and unexplained excessive hair growth should not be ignored.

Symptoms of Hypertrichosis

The main sign of hypertrichosis is excessive hair growth.

Depending on the type, you may notice:

• Unusually dense hair in one area

• Excessive hair over large areas of the body

• Fine, soft hair in unusual locations

• Thick or dark hair that grows longer than expected

• A hairy patch present from birth

• New hair growth after starting a medication

• Sudden or rapidly increasing hair growth

Hypertrichosis itself may not cause pain. However, an underlying condition may produce other symptoms.

When Should You See a Doctor?

Not every case of excessive hair growth requires urgent medical attention. However, you should speak with a healthcare professional if the hair growth:

• Appears suddenly

• Increases rapidly

• Becomes widespread without an obvious reason

• Begins after starting a new medication

• Occurs together with unexplained weight loss or fever

• Appears as a new hairy patch over the lower back

• Occurs alongside other unexplained physical changes

In particular, rapidly developing excessive hair growth requires evaluation because it can rarely indicate an underlying systemic illness or cancer-related condition.

How Is Hypertrichosis Diagnosed?

Doctors usually begin with a physical examination and a detailed medical history.

During the evaluation, your healthcare professional may ask:

• When did the excessive hair growth begin?

• Has it increased recently?

• Which areas of the body are affected?

• Does anyone in your family have similar hair growth?

• Have you recently started any medication?

• Do you have other new symptoms?

The doctor may also examine the type, color, thickness, and distribution of the hair.

If an underlying condition seems possible, the doctor may recommend additional blood tests, hormone-related tests, imaging, or other investigations based on your symptoms and medical history.

How Is Hypertrichosis Treated?

Treatment depends on the cause and the person’s preferences.

If a medication or underlying illness causes the excessive hair growth, the healthcare professional will first address that cause when possible. Meanwhile, people who want to reduce unwanted hair can choose from several hair-removal methods.

1. Shaving

Shaving cuts hair at the skin’s surface. It is simple, inexpensive, and generally safe when performed correctly.

However, hair grows back, so you need to repeat the process regularly.

Important: Shaving does not make hair follicles produce more hair.

2. Waxing

Waxing removes hair from the root. As a result, the skin may remain hair-free longer than it does after shaving.

However, waxing can cause temporary redness, irritation, ingrown hairs, or skin sensitivity.

3. Depilatory Creams

Depilatory creams chemically break down hair at the skin’s surface.

Always follow the product instructions and perform a patch test when recommended. Some people may experience skin irritation or an allergic reaction.

4. Electrolysis

Electrolysis uses an electrical current to target individual hair follicles.

It can provide long-term hair removal, although you may need multiple sessions because hair grows in different cycles.

5. Laser Hair Removal

Laser hair removal can provide longer-lasting hair reduction.

The results vary according to factors such as hair color, skin type, hair thickness, and the treatment area. You may need several sessions to achieve the desired reduction.

Can Hypertrichosis Be Cured?

The answer depends on the cause.

When a medication or treatable medical condition triggers acquired hypertrichosis, addressing the underlying cause may reduce further hair growth.

However, genetic forms of hypertrichosis may not have a permanent cure. In those cases, regular hair-removal treatments can help manage unwanted hair.

Is Hypertrichosis Dangerous?

Hypertrichosis itself is often not dangerous. For many people, unwanted hair mainly creates cosmetic or emotional concerns.

However, the underlying cause can sometimes require medical attention. Therefore, sudden or rapidly progressive hair growth deserves evaluation, especially when other symptoms appear at the same time.

Frequently Asked Questions

Is hypertrichosis a rare condition?

Some congenital forms of hypertrichosis are extremely rare. Acquired excessive hair growth can occur for several reasons, including medications and certain medical conditions.

Can women develop hypertrichosis?

Yes. Hypertrichosis can affect both women and men because it does not specifically depend on a male-pattern distribution of hair.

Does shaving make hypertrichosis worse?

No. Shaving does not increase the number of hair follicles or make hair grow faster. It simply cuts the visible hair shaft.

Can medication cause hypertrichosis?

Yes. Several medications, including minoxidil, phenytoin, cyclosporine, bimatoprost, and latanoprost, can cause excessive hair growth in some people.

Is hypertrichosis the same as PCOS-related hair growth?

Not usually. PCOS commonly causes hirsutism, which involves androgen-related hair growth in a male-pattern distribution. Hypertrichosis is a separate condition and generally involves non-androgen-dependent excessive hair growth.

Can laser hair removal treat hypertrichosis?

Laser hair removal can provide longer-lasting hair reduction for some people. However, results vary, and multiple treatments are usually necessary.

When should sudden hair growth worry me?

You should seek medical evaluation if excessive hair growth develops suddenly, progresses quickly, or appears with other unexplained symptoms. Although serious causes are uncommon, doctors may need to rule out an underlying illness or medication-related cause.

Final Takeaway

Hypertrichosis causes excessive hair growth that can affect a small area or much of the body. Congenital hypertrichosis develops from birth, while acquired hypertrichosis develops later and may relate to medications, medical conditions, nutritional problems, skin irritation, or other factors.

Fortunately, several treatment options can help manage unwanted hair. Shaving, waxing, depilatory creams, electrolysis, and laser hair removal can all play a role. At the same time, doctors should investigate sudden or rapidly progressive hair growth to identify any underlying cause.

If you notice unexplained changes in hair growth, speak with a qualified healthcare professional for an appropriate evaluation.

Medical Disclaimer: This article is for educational purposes only and does not replace professional medical advice, diagnosis, or treatment.