What is polymorphic light eruption?
Last updated September 3, 2026.
The most common sun-sensitivity condition: an immune-mediated rash - itchy bumps, patches, or blisters on newly exposed skin, hours to days after the first strong sun of the year - that eases as summer builds tolerance and recurs annually, usually starting in the teens or 20s. It is benign: resolves without scarring in about 10 days. Management: shade the flare, OTC hydrocortisone or antihistamine for itch, and graduated spring exposure plus high SPF to prevent the rerun; severe cases get prescription treatment or supervised phototherapy "hardening." Pymander's escalation routing is built and tested specifically for this class of decision; see the safety architecture working paper.
What to do
- Shade the flare: it resolves on its own in about 10 days without scarring.
- Treat the itch: cool compresses, OTC hydrocortisone, or an antihistamine.
- Prevent the rerun: graduated spring sun plus high-SPF sunscreen builds tolerance.
- Get seen if: it is your first episode, severe, or persistent - lupus and medication photosensitivity can mimic it.
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