Skin Problems & Treatments Health Center

Understanding Actinic Keratosis -- the Basics

What Is Actinic Keratosis?

Actinic keratoses are lesions on the outer skin layer caused by too much exposure to the ultraviolet rays of sunlight. They are also the beginnings of skin cancer, most often appearing after age 40. In some areas where climate is mild year-round -- like Florida and California -- these lesions appear in much younger people, even teenagers.

People with fair skin, blond or red hair, and blue or green eyes are most at risk of developing these rough, scaly "bumps." A history of burning rather than tanning also increases risk. If not treated, these bumps can develop into a more serious form of skin cancer, although this is unusual.

To prevent actinic keratoses, it's important to:

• Avoid exposure to sunlight during peak sunlight hours (9 a.m. to 4 p.m.).
• Wear clothing that covers arms and legs.
• Wear a wide-brimmed hat -- not just a cap -- or carry an umbrella when outdoors during peak sunlight hours.
• Use sunscreen with sun protection factor (SPF) of 50 or higher, applying it at least 15 to 30 minutes before sun exposure.
• Choose a sunscreen that provides both UVA and UVB protection.
• Reapply sunscreen every two to three hours when outdoors, even on cloudy days.
• Remember that it is the light from the sun that can be dangerous -- not the heat -- so you can be at risk even if the temperature is mild.