Photoirritation

Photoirritation, also known as photosensitivity or phototoxicity, refers to an adverse skin reaction that occurs when the skin is exposed to ultraviolet (UV) radiation or visible light after the application of certain substances. These substances, called photosensitizers, can be ingested, injected, or applied topically. When exposed to light, the photosensitizer absorbs energy and undergoes a chemical change that damages surrounding skin cells.

The reaction typically resembles an exaggerated sunburn. Symptoms can range from mild redness, itching, and burning to more severe blistering, swelling, and pain. The severity of the photoirritation depends on the specific photosensitizer, its concentration, the duration and intensity of light exposure, and individual sensitivity.

Common causes of photoirritation include certain medications (such as some antibiotics, diuretics, and nonsteroidal anti-inflammatory drugs), topical products (like retinoids, some fragrances, and sunscreens containing specific UV filters), and even certain plants (like limes and parsnips, which contain psoralens).

Diagnosis is usually based on the patient's history of light exposure and the use of photosensitizing agents, along with a characteristic skin presentation. Treatment involves avoiding further exposure to the offending agent and light, and managing symptoms with cool compresses, emollients, and in severe cases, topical or oral corticosteroids. Prevention is key and involves being aware of potential photosensitizing agents and protecting the skin from sunlight.