Sun rash and sun allergy are terms often used to describe a number
of conditions in which an itchy red rash occurs on skin that's been
exposed to sunlight. The most common form of sun rash is
polymorphic light eruption, also known as sun poisoning.
Some people have a hereditary type of sun allergy, while others
develop signs and symptoms only when triggered by another factor —
such as certain types of medications or skin exposure to certain
plants, such as limes or wild parsnip.
Mild cases of sun rash may resolve without treatment. More-severe
cases may require steroid creams or pills. People who have a severe
sun allergy may need to take preventative measures, such as:
Limit exposure. Avoid spending time in the sun, especially when
the sun's rays are most intense — between 10 a.m. and 4 p.m.
Use sunscreen. Use a high-SPF sunscreen that specifically
blocks both ultraviolet A and ultraviolet B rays. Apply sunscreen
generously, and reapply every two hours — or more often if
you're swimming or perspiring.
Cover up. Wear a broad-brimmed hat and cover your arms and
legs with clothing that's tightly woven or specifically designed to
protect from the sun.