Fotoallergia

Fotoallergia, also known as photodermatitis or sun allergy, is an immune system reaction that occurs when skin is exposed to sunlight. It is not a true allergy in the IgE-mediated sense but rather a cell-mediated hypersensitivity. The reaction is triggered by a combination of sunlight and a specific substance, which can be a medication, cosmetic, or a chemical naturally present in the skin. When this substance absorbs ultraviolet (UV) radiation, it undergoes a chemical change, creating a molecule that the immune system recognizes as foreign. This leads to an inflammatory response.

Symptoms of fotoallergia can vary but commonly include itching, redness, swelling, and the appearance of small bumps or blisters on sun-exposed areas of the skin. These reactions typically appear within hours to a few days after sun exposure. The severity and location of the rash depend on the individual's sensitivity and the extent of sun exposure.

The diagnosis of fotoallergia usually involves a thorough medical history, physical examination, and sometimes photopatch testing. This test involves applying potential allergens to the skin and then exposing small areas to UV light to reproduce the reaction under controlled conditions. Identifying the causative agent is crucial for management.

Treatment focuses on avoiding the trigger substance and protecting the skin from sunlight. This includes using broad-spectrum sunscreens with high SPF, wearing protective clothing, and seeking shade. In cases of severe reactions, topical corticosteroids or oral medications may be prescribed to manage inflammation and itching. Prevention is key, and individuals diagnosed with fotoallergia should be vigilant about sun protection and aware of potential triggers in their environment, including medications and personal care products.