What causes sun sensitivity?

Sunlight contains ultraviolet radiation that can injure skin cells and activate inflammation. Some medicines and plant chemicals make the skin react more strongly after light exposure; a rash may appear on exposed areas after a delay. Other people have a condition such as cutaneous lupus, photodermatitis, or polymorphic light eruption, in which the immune system responds abnormally to sunlight.

The pattern helps guide assessment. Burning or blistering soon after exposure, an itchy clustered rash that returns with sunny weather, and symptoms limited to exposed skin point to different possibilities. Reactions can also be worsened by reflective surfaces, prolonged outdoor time, or light passing through thin clothing or windows.

Use shade, closely woven clothing, a broad-brimmed hat, and a broad-spectrum sunscreen that suits your skin. Reapply sunscreen as directed on the product label, especially after sweating or swimming. Review medicines and supplements with a pharmacist or clinician rather than stopping a prescribed treatment on your own.

Keep a brief record of the timing, body areas, products, medicines, and outdoor conditions linked to each episode. A clinician may use this pattern to decide whether testing, a medication change, or treatment for an underlying skin condition is needed.

Arrange medical advice for repeated reactions, a rash that does not settle after avoiding sunlight, marked blistering, or symptoms after starting a new medicine. Seek urgent help for facial swelling, breathing difficulty, widespread blistering, severe skin pain, eye pain, or sores in the mouth.

Could a medicine or supplement be making me light-sensitive? Does the rash pattern suggest cutaneous lupus, photodermatitis, or polymorphic light eruption? What level of sun protection is appropriate? Do I need an eye or medication review?