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Chronic reactions to sunlight exposure
Medical expert of the article
Last reviewed: 07.07.2025
Skin aging
Chronic exposure to sunlight ages the skin (dermatoheliosis, extrinsic aging), resulting in wrinkles, rough skin, patchy hyperpigmentation, and sometimes telangiectasias. Atrophic reactions may occur in some individuals and resemble the skin reaction to X-ray therapy (chronic solar dermatitis).
Actinic keratosis
Actinic keratosis is a precancerous lesion that often develops due to prolonged sun exposure. People with fair or red hair and skin type I or II are most susceptible, while black people are rarely affected. Pink keratotic lesions with unclear borders and the formation of light gray or dark scales develop. Actinic keratosis should not be confused with seborrheic keratosis, which causes brown warts that increase in number with age and can also occur on skin areas not exposed to the sun.
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Skin cancer
The incidence of basal cell carcinoma in fair-skinned people is directly proportional to annual sun exposure. Such lesions usually occur in people who are frequently exposed to the sun, such as children and adolescents, athletes, farmers, and sailors. Frequent sun exposure also increases the risk of developing malignant melanomas.
Treatment of skin reactions to sunlight exposure
Various drug combinations have been used to improve the cosmetic appearance of chronic sun damage: chemical peels, 5-fluorouracil (5FU), tretinoin, topical alpha hydroxy acids. These treatments appear to improve wrinkles and fine lines, pigmentation, yellowness, and laxity or roughness of the skin, but do not help with telangiectasias. Laser treatment may also be used. However, many of the chemicals used in cosmetics have not been proven to provide protection against chronic sun damage.
For mild actinic keratosis, the fastest and most appropriate treatment is cryotherapy with liquid nitrogen. If the lesions are too extensive to use cryotherapy, 5FU applied nightly or twice daily for 2-4 weeks is usually sufficient. Many patients tolerate 0.5% 5FU cream applied to the face once daily for 4 weeks. Actinic keratosis of the hands may require a higher concentration, such as 5% cream. Topical 5FU causes redness, flaking, and a burning sensation that often occurs in areas of healthy skin. If the reaction to the treatment is too severe, the treatment may be discontinued for 2-3 days. Topical 5FU has no significant adverse effects other than those listed above, which can be masked with cosmetics or treated with topical glucocorticoids. 5FU should not be used to treat basal cell carcinoma unless the lesions are superficial.