context: The sun produces invisible rays called ultraviolet- A ( UVA) or ultraviolet- B ( UVB) that can damage the skin. Too much sun can cause sunburn, skin texture changes, and skin cancers. Rashes also can be attributed to sunlight. Even on cloudy days, UV radiation reaches the earth and can cause skin damage. Sunburn is a condition that occurs when the amount of exposure to the sun or another ultraviolet light source exceeds the ability of the body's protective pigment (melanin) to protect the skin. Symptoms of sunburn include painful, reddened skin; however, sunburn may not be immediately apparent. By the time the skin starts to become painful and red, the damage has been done. Severe sunburn may result in swelling and blisters. People who are severely sunburned may develop a fever, chills, and/or weakness. In rare cases, people with sunburn can go into shock. Several days after sunburn, people with naturally fair skin may have peeling in the burned areas. Some itching may occur, and the peeled areas are even more sensitive to sunburn for several weeks. The sunburned areas are more susceptible to premature aging and skin cancer down the road. Susceptibility to sunburns is increased in people with: Fair skin Light-colored hair People using certain medications that increase the skin's sensitivity to sunburn, such as NSAIDs (ibuprofen and naproxen, for example), antibiotics (like quinolones, tetracyclines and sulfonamides), antimalarials (like Chloroquine), amiodarone, griseofluvin, psoralens, thiazides (furosemide), and the phenothiazines (antipsychotic medications). To treat -- or ease the discomfort of -- sunburn: Apply a cold compress to the affected area(s). Take aspirin or acetaminophen ( Tylenol) immediately after exposure to the sun to relieve sunburn discomfort and inflammation. Apply a cooling gel or ointment containing aloe vera to the sunburned area or areas. Avoid further sun exposure until the discomfort resolves. In cases of severe sunburn or sunstroke, see your doctor immediately. Most people's skin will burn if there is enough exposure to ultraviolet radiation. However, some people burn particularly easily or develop exaggerated skin reactions to sunlight. This condition is called photosensitivity. People often call this a sun allergy. People with photosensitivity have an immunological response to light -- most often sunlight. They can break out in a rash when exposed to sunlight. The amount of exposure required to cause a reaction varies from person to person. Some people with photosensitivity are also affected by indoor fluorescent lighting. Photosensitivity has been linked to: Contact with chemicals, fragrances, or plants Medicines (including sulfonamides, tetracycline, and thiazide diuretics) that are taken internally Herbs including St. John's wort Autoimmune diseases such as lupus erythematosus Porphyria, a metabolic disorder that is sometimes hereditary Symptoms of photosensitivity Symptoms of photosensitivity may include a pink or red skin rash with blotchy blisters, scaly patches, or raised spots on areas directly exposed to the sun. Itching and burning may occur and the rash may last for several days. In some people, the reaction to sunlight gradually becomes less with subsequent exposures. Photosensitivity treatments Some types of photosensitivity may respond to specific treatments such as oral beta-carotene, steroids, or other medications. Polymorphic light eruption ( PMLE) is a condition in which skin rashes can develop after fairly limited sun exposure. PMLE usually affects females between ages 20 and 40. The condition also can affect children and less commonly, men. Symptoms of PMLE The term 'polymorphic' refers to the fact that the rash can take many forms. A common kind of PMLE resembles groups of pink or red raised spots on the arms. Other areas, including the legs and chest, also may be affected. Sometimes the rash has blisters and larger dry, red spots. The rash is accompanied by burning or itching that can last for several days. PMLE Treatments In severe cases, a doctor may recommend oral steroids to treat PMLE. Hydroxychloroquine, a drug used to treat skin conditions, sometimes is recommended. To protect your skin from the sun, consider these tips: Avoid the sun during peak UVB hours (usually 10 a.m. to 2 p.m.) Dress sensibly. The tighter the weave and darker the colors of the fabric, the more sun protection it will offer. Wear a wide-brimmed hat and sunglasses. Avoid deliberate sunbathing, including tanning beds. Use a sunscreen of at least 30 SPF with a physical blocker such as zinc oxide every day, even on cloudy days. Sunscreens should be applied about 20 minutes before going outdoors. Even water-resistant sunscreens should be reapplied about every 80 minutes, after swimming, or after strenuous activity. Different sunscreens are appropriate for different people. For children under 6 months old, the best option is to keep them out of the sun, if possible. If sun exposure is unavoidable, put a little bit of sunscreen with zinc oxide and a SPF of at least 30 on small areas such as the cheeks and back of the hands, after testing to see if the baby is sensitive by first trying a small amount on the baby's wrist. The fewer number of ingredients in the sunscreen, the less likely the sunscreen is to cause an irritating skin reaction. Even people with dark skin benefit from zinc oxide sunscreen with an SPF of at least 30. Sunscreen and sun avoidance decrease the incidence of cancer and unevenness of pigmentation in people of all skin colors. Many zinc oxide physical blocker sunscreens are easy to rub in, unlike the zinc oxide products of just a few years ago.