Sunburn signs and symptoms include:

• Pinkness or redness
• Skin that feels warm or hot to the touch
• Pain, tenderness and itching
• Swelling
• Small fluid-filled blisters, which may break
• Headache, fever, nausea and fatigue if the sunburn is severe

Any exposed part of your body — including your earlobes, scalp and lips — can burn. Even covered areas can burn if, for example, your clothing has a loose weave that allows ultraviolet (UV) light through. Your eyes, which are extremely sensitive to the sun's UV light, also can burn. Sunburned eyes may feel painful or gritty.

Signs and symptoms of sunburn usually appear within a few hours after sun exposure. But it may take a day or longer to know the full extent of your sunburn.

Within a few days, your body may start to heal itself by "peeling" the top layer of damaged skin. After peeling, your skin may temporarily have an irregular color and pattern. A bad sunburn may take several days or longer to heal.

Sunburns are caused by exposure to too much ultraviolet (UV) light. UV radiation is a wavelength of sunlight in a range too short for the human eye to see. Ultraviolet A (UVA) is the type of solar radiation most associated with skin aging (photoaging). Ultraviolet B (UVB) is associated with sunburn. Exposure to both types of radiation is associated with developing skin cancer. Sunlamps and tanning beds also produce UV light and can cause sunburn.

Melanin is the dark pigment in the outer layer of skin (epidermis) that gives your skin its normal color. When you're exposed to UV light, your body protects itself by accelerating the production of melanin. The extra melanin creates the darker color of a tan.

A suntan is your body's way of blocking the UV rays to prevent sunburn and other skin damage. But the protection only goes so far. The amount of melanin you produce is determined genetically. Many people simply don't produce enough melanin to protect the skin well. Eventually, UV light causes the skin to burn, bringing pain, redness and swelling.

You can get sunburn on cool, hazy or cloudy days. As much as 80 percent of UV rays pass through clouds. Snow, sand, water and other surfaces can reflect UV rays, burning your skin as severely as direct sunlight.

Risk factors for sunburn include:

• Having light skin, blue eyes, and red or blond hair
• Living or vacationing somewhere sunny, warm or at high altitude
• Working outdoors
• Mixing outdoor recreation and drinking alcohol
• Having a history of sunburn
• Regularly exposing unprotected skin to UV light from sunlight or artificial sources, such as tanning beds

Taking a drug that makes you more likely to burn (photosensitizing medications)

Intense, repeated sun exposure that results in sunburn increases your risk of other skin damage and certain diseases. These include premature aging of your skin (photoaging) and skin cancer.

Premature aging of your skin

Sun exposure and repeated sunburns accelerate the skin's aging process, making you look older than you are. Skin changes caused by UV light are called photoaging. The results of photoaging include:

• Weakening of connective tissues, which reduces the skin's strength and elasticity
• Deep wrinkles
• Dry, rough skin
• Fine red veins on your cheeks, nose and ears
• Freckles, mostly on your face and shoulders
• Dark or discolored spots (macules) on your face, back of hands, arms, chest and upper back — also called solar lentigines .

Precancerous skin lesions

Precancerous skin lesions appear as rough, scaly patches in areas that have been damaged by the sun. They may be whitish, pink, tan or brown. They're usually found on the sun-exposed areas of the head, face, neck and hands of light-skinned people. These patches can evolve into skin cancer. They're also called actinic keratoses and solar keratoses.

Skin cancer

Excessive sun exposure, even without sunburn, increases your risk of skin cancer, such as melanoma. It can damage the DNA of skin cells. Sunburns in childhood and adolescence may increase your risk of developing melanoma later in life.

Skin cancer develops mainly on areas of the body most exposed to sunlight, including the scalp, face, lips, ears, neck, chest, arms, hands and legs. Skin cancer on the leg is more common in women than in men.

Some types of skin cancer appear as a small growth or a sore that bleeds easily, crusts over, heals and then reopens. With melanoma, an existing mole may change or a new, suspicious-looking mole may develop. A type of melanoma called lentigo maligna develops in areas of long-term sun exposure. It starts as a tan flat spot that slowly darkens and enlarges.

See your doctor if you notice a new skin growth, a bothersome change in your skin, a change in the appearance or texture of a mole, or a sore that doesn't heal.

Eye damage

The sun can also burn your eyes. Too much UV light damages the retina, lens or cornea. Sun damage to the lens can lead to clouding of the lens (cataracts). Sunburned eyes may feel painful or gritty. Sunburn of the cornea is also called snow blindness.