context: If you have lupus, you might be photosensitive -- meaning you have an unusually strong reaction to sunlight. In fact, about two-thirds of the people with lupus are UV light-sensitive. Many experience an increase in lupus symptoms after being exposed to ultraviolet ( UV) rays, either from the sun or from artificial light. Photosensitive people may develop a skin rash, known as a butterfly rash, which appears over the nose and cheeks after sun exposure. Other rashes might look like hives. Sunlight may cause also a lupus flare, resulting in fever, joint pain, or even organ inflammation. Each person with lupus may have a different level of photosensitivity - just like in the general population. If photosensitivity is a problem for you, here are some ways to protect yourself from the sun: If you are photosensitive, the best rule is to avoid midday and tropical sun entirely. Unfortunately, that's not always the most practical advice, especially if your job or family situation requires that you spend time outside or near UV rays. People with lupus should not stay in the sun for extended periods and should make every effort to avoid UV rays outside, which are at their peak between 10 a.m. and 4 p.m. Don't be fooled by an overcast day, because clouds don't filter out all of the sun's UV rays. Keep track of the time you spend in the sun. It can take anywhere from hours to days before skin abnormalities occur from sun exposure. Anyone who is out in the sun for more than 20 minutes daily should apply sunscreen, but people who have lupus should be especially vigilant. Sunscreen should have a sun protection factor ( SPF) of at least 30. Studies used to suggest that UVB rays -- the rays responsible for burning -- were most dangerous to people with lupus. But more recent research shows that UVA rays -- those responsible for wrinkling the skin -- can also aggravate lupus. With that in mind, you should look for broad-spectrum protection sunscreen that blocks both UVA and UVB rays. Apply sunscreen liberally: It takes at least 1 ounce of sunscreen to cover your entire body. Remember to reapply at least every 2 hours. Sweat, water, contact, and clothing can all rub off the sunscreen you've applied. People often forget to apply sunscreen to their necks, backs, and ears, all of which are commonly affected by photosensitivity related to lupus. Because it is not always possible to avoid the sun entirely, people with lupus should protect themselves with clothing, too. Rashes caused by photosensitivity usually occur on parts of the body that are most often exposed to sun, including the face, neck, ears, and hands. Hats with large brims, along with tightly woven, loose-fitting, long-sleeved shirts and long pants can help provide maximum coverage from the sun. People with lupus who work or spend a lot of time outside should consider wearing clothing that has built-in sun protection or using an umbrella made with special fabric designed to block UV rays. If you are fair-skinned and have light eyes and light hair, you should be even more careful when exposed to UV rays, because people with those features are more sensitive to the sun and artificial light than people who have darker hair and skin. Many indoor offices and businesses use halogen and fluorescent light bulbs. Copy machines also have lighting mechanisms that emit UV rays that can cause lupus symptoms. Fortunately, there are shades, shields, filters, and tube covers available through several manufacturers that can offer protection from UV rays that aggravate your lupus. You can eliminate UV rays emitted by photocopiers by simply closing the cover of the machine while the copier is in use. Remember that windows do not offer full protection from UV rays. Your lupus can actually be aggravated by harmful rays you receive through a car or building window, so it is best to protect yourself with window shades or films that block UV rays. Many medications, including some used to treat lupus, can magnify the effects that sun has on a person's body, making them even more susceptible to the hazards of UV rays. Make sure to ask your doctor whether or not your medications will increase your sensitivity to sun or artificial light.