Extreme sensitivity to ultraviolet rays (photosensitivity) may cause a red, itchy rash to erupt on the skin within a matter of minutes. Sun poisoning, which medical professionals call polymorphous light eruption, typically presents in the form of small papules (bumps) and less commonly in plaques (hives) on the exposed areas of skin. Although the amount of UV exposure that causes sun rash varies depends on the individual, most people have a minimum threshold of how long they can be exposed to UV rays before the rash erupts, says the American Osteopathic College of Dermatology. Sun poisoning resolves on its own--in a few days or a week--and generally requires no other medical care than at-home prevention and treatment.
Apply cold compresses to sun rash using a towel dampened with cool water, advises the Mayo Clinic. An over-the-counter, 1 percent hydrocortisone cream can relieve itching, but if you want to go the natural route, integrative physician Dr. Andrew Weil suggests applying soothing topical aloe vera gel to the rash.
To decrease redness and pain, the ibuprofen or aspirin in your medicine cabinet can be helpful, says Mayo Clinic experts. Weil also suggests taking Zyflamend, manufactured by New Chapter, an herbal anti-inflammatory, as well as 2 to 3 g of fish oil each day to reduce inflammation associated with sun rash.
Avoiding direct sunlight is the best protection against sun rash–and this includes eschewing tanning beds and sun lamps, too. If you have to go outdoors, Weill suggests applying sunscreen with a sun protection factor of at least 15 at least 20 minutes before heading out the door. Carry your sunscreen with you and reapply it every two hours. Mayo Clinic experts suggest donning tightly-woven clothing that covers your arms and legs and wearing a wide-brimmed hat whenever you go outdoors.
If possible, stay out of the sun when UV rays are the strongest, says the AOCD–between 11 a.m. and 3 p.m. Weil takes a more slightly different approach to sun exposure and advocates avoiding the sun's rays from between 10 a.m. and 2 p.m. (especially during the months of April through September). The Mayo Clinic take the most conservative approach and advises staying indoors between 10 a.m. and 4 p.m.