Response is not observed for 1 - 3 days after the substance has come into contact with the body
Photosensitivity is an increased sensitivity or abnormal response of the skin to sunlight or artificial light. In particular, exposure to both UVA and UVB rays have been seen to trigger unusual reactions of the skin in people with certain disorders or those who are taking particular medications or substances. Redness (erythema) of the skin, similar to sunburn or rash or the sun-exposed area.
A phototoxic reaction from medication usually clears up when the drug is no longer used or in the body, even after re-exposure to the original light source.
It’s the combination of the photosensitizing medications or chemical substance plus the light source that causes the photosensitivity reaction.
In photoallergic reactions, the body’s immune system sees the antigen as an enemy combatant. The immune system then kicks off an allergic response causing inflammation of the skin in the sun-exposed area. This type of photosensitivity may recur after sun exposure even after the drug has been cleared from the system and can sometimes spread to areas of the skin unexposed to the sun.