Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025
Definition
Phototoxicity is a skin reaction caused by exposure to light, typically ultraviolet (UV) radiation, in the presence of certain chemicals or medications. It can result in severe sunburn-like symptoms.
5 Must Know Facts For Your Next Test
Phototoxic reactions occur when a drug absorbs UV light and releases it into the skin, causing cellular damage.
Common antimicrobial drugs associated with phototoxicity include tetracyclines, fluoroquinolones, and sulfonamides.
Symptoms of phototoxicity can include redness, swelling, blistering, and pain on areas exposed to sunlight.
Preventative measures for phototoxicity include wearing protective clothing and using broad-spectrum sunscreen when outdoors.
Phototoxicity is different from photoallergy; the latter involves an immune response while phototoxicity does not.
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Related terms
Photoallergy: An allergic reaction that occurs when UV light activates an allergen on the skin.
Photosensitivity: A general term describing various conditions where skin reacts abnormally to sunlight.
Ultraviolet (UV) Radiation: A type of electromagnetic radiation from the sun that can cause skin damage.