Hyperpigmentation is the medical term used to describe any darkening of the skin compared to the usual color of the skin. The term is comprised of the parts “hyper,” meaning excessive, and “pigmentation,” meaning coloring. Melanin is the pigment that gives color to the skin, hair, and nails. The wide range of skin tones seen all around the world is determined by the amount of melanin that the body normally produces in the skin. Melanocytes are the cells in the skin that produce melanin.

As the largest organ of the body, the skin—in all its various hues—has many functions. It helps to regulate body temperature and protects the body from environmental elements.

A variety of factors may affect the skin and cause melanocytes to ramp up the production of melanin. In many cases, these reactions are actually part of the skin’s natural defense or healing processes. Consider the darkening of the skin after sun exposure. This darkening or “tanning” is intended to help protect the skin from the damage caused by sun exposure. However, sometimes these natural and necessary processes can lead to long-lasting changes in skin color.

Some forms of hyperpigmentation have a unique appearance, distribution (where it appears on the skin), or cause. These forms may have a specific name, like melasma or lentigines (“liver spots”).

Where Does Hyperpigmentation Usually Occur?

Hyperpigmentation is mostly seen in parts of the body commonly exposed to the sun, such as the face, neck, chest, and arms. This makes sense since sun exposure is a leading cause of melanocyte activation and melanin production. However, friction can also contribute to the formation of hyperpigmentation. This means—perhaps counterintuitively—that areas not frequently exposed to the sun, such as the armpits and groin, are also common sites for hyperpigmentation. The neck, elbows, and knees may also be susceptible to hyperpigmentation, perhaps through a combination of sun exposure and friction. Acanthosis nigricans is a condition in which dark discoloration of the skin folds is accompanied by a velvety thickening of the skin.

What Factors Contribute to Hyperpigmentation?

Hyperpigmentation may be caused by a number of factors and in most cases, a combination of causes may be involved. These may include:

  1. Sun/UV Exposure

Ultraviolet rays can damage the skin even with short periods of exposure, instigating a skin response that includes the production of melanin. The sun is the primary source of UV exposure. Sun lamps or tanning beds are another sources. A good sunscreen with sufficient SPF is essential to minimize UV-induced skin damage.

  1. Inflammation

Illness, skin diseases (like eczema and acne), bug bites, and even UV exposure can cause inflammation in the skin. As part of the skin’s inflammatory response, melanocytes are activated to produce melanin.

  1. Hormones

Changes in hormone levels can lead to changes in melanin production. Hormonal changes in puberty, pregnancy, and menopause may be implicated in skin color changes. Birth control pills or other hormonally based therapies may also impact skin pigmentation.

  1. Pregnancy

Hormonal surges during pregnancy have such a potentially significant effect on skin pigmentation that “the mask of pregnancy” emerged as a term to describe the darkening of the central face that occurs during pregnancy.  

  1. Diabetes

Diabetics are more likely to experience hyperpigmentation and acanthosis nigricans. The nature of the relationship is still unknown, but it appears to be a two-way street. Individuals who develop hyperpigmentation in the armpits, groin, or joints are more likely to suffer from diabetes later in life.

  1. Obesity

Obesity may best be considered a risk factor for hyperpigmentation, rather than a cause. Obesity may influence pigmentation through some known pathways. For example, certain forms of obesity are associated with systemic inflammation; inflammation can increase the risk for hyperpigmentation. As the skin stretches to accommodate weight gain, friction in the joints and skin folds may increase; friction can increase the risk for hyperpigmentation.

  1. Race/Ethnicity

Hyperpigmentation is more likely to be seen in those with naturally darker skin. Individuals of Latino, African, and Asian descent have a greater incidence of hyperpigmentation.

  1. Infections

Fungal and/or bacterial infections are common in areas of excessive friction or where there is moisture on the skin (from sweat, such as in the armpits and groin, beneath the breasts, etc.). The presence of microbes can increase inflammation and may contribute to hyperpigmentation.

What Are Some of the Most Common Types of Hyperpigmentation?

Generalized hyperpigmentation is a common concern. Specific forms of hyperpigmentation may include: 

Hyperpigmentation in Brief

Hyperpigmentation is the medical term used to describe any darkening of the skin compared to the usual color of the skin. It is comprised of the words “hyper,” meaning excessive, and “pigmentation,” meaning coloring. It is caused by an increase in the skin pigment melanin, produced by cells called melanocytes.

Did You Know?

Age is sometimes considered a risk factor for developing hyperpigmentation, but the relationship may not be so simple. Concerns about “liver spots” or melasma may increase as patients reach middle age and beyond, but as we age, we also have more cumulative UV exposure. A lifetime of hormonal fluctuation may manifest in skin changes later in life. The reality is that most patients will begin to see subtle skin changes, including fluctuations in pigmentation, by age 25.

Hyperpigmentation Fast Fact

A grading system called the Fitzpatrick skin phototype scale is a standardized approach that was developed to assess skin features. The scale ranges from I (pale white) to VI (dark brown or black).