Though it sounds quite technical, hyperpigmentation happens to all of us—in one form or another. Usually harmless, it’s a common condition in which patches of skin become darker than the normal, surrounding skin. This darkening occurs when an excess of melanin, the brown pigment that produces normal skin color, forms deposits in the skin. These can be tiny pinpoints, freckles, or significantly larger spots. 

    Causes: Hyperpigmentation is caused by the fact that your skin is continually in and out of the sun, meaning your melanocytes are constantly being turned on and off. Excessive sun exposure causes certain melanocytes to multiply, producing an uneven distribution in the skin. Increased levels of melanin production by certain melanocytes and not others can cause a patchy, uneven, “blotchy-looking” accumulation of melanin on the skin. Called lentigenes, these areas of hyperpigmentation are known as age spots or liver spots. 

    Sun Exposure and Inflammation: Exposure to UV rays causes skin inflammation. If severe, the result is a sunburn. But even tiny amounts of exposure, such the kind you incur by simply walking to your car, can cause subtle, inflammatory processes to be initiated in your skin. 

    How Inflammation Activates Melanocytes: Mere exposure to sunlight causes skin inflammation. This inflammation triggers the activation of melanocytes. Sun exposure can cause an overproduction of melanocytes, but so can spicy foods and alcohol. This kind of inflammation may result in vasodilation of the blood vessels, increasing redness; increased vascular leakiness of fluid into the skin, causing swelling; overactive nerve endings, causing pain; and an increased release of histamine, causing itching and irritation.

    Other Factors Contributing to Inflammation and Hyperpigmentation: Any external stimulus that damages the skin triggers inflammation, which then activates melanocytes. Examples of inflammation induced pigmentation include topical and oral antibiotics (e.g., tetracycline), Accutane, topical retinoids, as well as common irritants such as fabric dyes and plants (e.g., poison ivy and poison oak). 

    One last note about Hyperpigmentation: Various forms of dermatitis, eczema, or chemically induced contact dermatitis can cause hyperpigmentation, as can acne, and any physical trauma to the skin (such as laser resurfacing procedures, cosmetic surgery, temperature changes, and chemical burns). Also, hormones, progesterone, and birth control pills can cause melasma, a skin discoloration associated with hormones. 

    Whether you have hyperpigmentation or melasma, any trauma to the skin can cause inflammation and trigger their onset.