What causes sun allergy?

In polymorphic light eruption, the immune system reacts to sunlight after skin receives more ultraviolet exposure than it has adapted to. Itchy red bumps, patches, or small blisters may appear on exposed areas, often after time outdoors. The rash can be delayed rather than appearing immediately, and its pattern may change from one episode to another.

Some people develop a similar reaction because a medicine, fragrance, plant substance, or skincare product makes the skin more sensitive to light. This is called a photosensitivity reaction. Sun Sensitivity can have several causes, so the timing, distribution, products, and medicines matter when a clinician assesses it.

Limit direct sun during the hours when exposure is strongest, seek shade, and cover exposed skin with closely woven clothing and a wide-brimmed hat. Introduce outdoor exposure gradually and use a broad-spectrum sunscreen that your skin tolerates. Keep a record of new medicines, fragrances, and products started before the rash, but do not stop a prescribed medicine without medical advice.

A clinician may recommend a short course of Topical Corticosteroids for an inflamed flare. Recurrent or difficult cases may be considered for Narrowband UVB Phototherapy under supervision, which can help the skin acclimatise in a controlled setting.

Arrange a medical review if the rash recurs, spreads beyond sun-exposed skin, leaves marked discoloration, or does not settle after avoiding sunlight. Seek prompt help for facial swelling, breathing difficulty, faintness, extensive blistering, fever, or a painful rash. Urgent assessment is especially important when a new medicine was followed by a widespread reaction.

Could this be polymorphic light eruption, a medicine reaction, or another skin condition? Which products or medicines should I review? What sun protection is realistic for my routine? Would supervised phototherapy or a topical medicine be appropriate if it returns?