Some PSD are due to the presence of drugs, hormones or heavy metals in the individual's skin. Photoallergies may also result when light rays interact with certain chemicals. It occurs in susceptible individuals when they are exposed to solar radiation that is more intense than usual, i.e. as in the first time in the sun that season or a body part that has no prior UV exposure. It may also occur when the patient travels to a higher latitude or lower latitude. Sunscreens are mandatory to protect from UVA and UVB, although UVA protective agents are more effective in preventing these eruptions.
Most susceptible individuals are female.
Onset of polymorphous light eruption usually occurs in the first 30 yrs of life. This abnormality causes the body to form and excrete excessive amounts of heme metabolites. The actual photosensitivity begins in childhood on sun-exposed areas. Individuals who suffer from porphyria must be protected from solar radiation by a physical blocking agent or by clothing. Some porphyria sufferers respond to oral beta carotene.