While several factors may contribute to irregular skin pigmentation, the condition often results from repeated episodes of sunburn, notes MedlinePlus. The look of patchy or mottled skin stems from an overproduction of the skin pigment known as melanin, which your body produces as a defense against the sun’s UV rays. Uneven production of melanin results in uneven skin tone. Unlike a temporary sunburn, it may take several years of sun exposure before skin discoloration begins to occur.

Types of Irregular Pigmentation

Whether it appears in patches or in larger swaths of color, the general term for discoloration due to sunburn is known as hyperpigmentation. Hyperpigmentation simply means that your skin has produced an excess of melanin. As their formal name, solar lentigines, suggests, liver spots have been connected to frequent UV exposure on the face, back, hands and other exposed parts of your body. The so-called "mask of pregnancy," melasma, may be worsened by sun damage. Poikiloderma is most often seen in older women, notes the Mayo Clinic.


Skin discoloration often shows itself uneven patches, giving the skin a mottled appearance. While fair-skinned people are more likely to develop the condition, darker skins may also suffer dark brown patches as a result of sun damage, notes the Mayo Clinic. The uneven pigmentation may be paired with premature wrinkles and broken blood vessels on the face, which are also related to sun exposure. Because sunburns often result from a day at the beach, liver spots may appear on any part of your body exposed while wearing a bathing suit, such as your back. They are generally rounded and brown. Poikiloderma marks tend to be reddish-brown, and appear on the neck and cheeks. Melasma shows itself as large, dark facial patches.

Aggravating Factors

Sunburns resulting in uneven skin pigmentation are more likely to occur when paired with certain other factors. The medication psoralens may trigger hyperpigmentation after a sunburn. A condition known as photodermatitis, the acute sensitivity to sunlight, can result in uneven pigmentation. Melasma may stem from a combination of sunburn and a surge in female hormones. Pregnancy may cause this hormone spike, as may birth control or hormone replacement pills. Researchers link poikiloderma to sun exposure on skin covered with perfume or cosmetics. Aging can worsen the tendency toward liver spots in people who've suffered sunburns throughout their lives.

Treatment and Prevention

Avoid exposure when the sun is at its peak strength, usually between 10 a.m. and 2 p.m. Sunglasses, full-coverage clothing and sunscreen of at least SPF 30 all help people with tendencies toward hyperpigmentation, notes MedlinePlus. Makeup may lessen the appearance of patchiness, while lotions such as hydroquinone help even out skin tone. The uneven pigmentation sometimes goes away by itself, but if not, you may opt for professional bleaching, chemical peels or laser therapy.

Additional Causes

Even when not combined with sunburn, other factors may cause uneven pigmentation. Among them are injury, inherited tendencies toward patchy skin, medication and hormone fluctuations, notes MedlinePlus. Conditions that affect your blood vessels, or bacterial growths such as ringworm, may also cause dark patches. A dermatologist can determine whether your condition is related to sun damage. It’s critical to see a doctor to rule out cancerous skin conditions. Seek medical help if you develop raised growths, or if the patchiness spreads or turns darker.