Light urticaria

Last Updated: 2019-08-26

Author(s): Anzengruber, Navarini

Merklen 1904

Urticaria solaris, solar urticaria, photoallergic urticaria, solar urticaria

Urticaria, which can be triggered by UV rays (from infrared to UVC).

UV radiation (from short-wave IR to long-wave UVC radiation) is the trigger. Almost all patients react to visible light. A precursor of the allergen (chromophore) absorbs incident UV radiation and becomes the photoallergen. Specific IgE leads to the release of histamine and the development of urticaria.

Urticaria in UV-exposed areas. In rare cases Quincke's oedema and anaphylactic reaction may occur.


Clinical picture

Photoprovocation testing (UVA, -B, -C, IR, visible light) with determination of minimal urticaria dose (MUD)

Serum factor test (not used for clinical routine) 

Anaphylactic reactions are described for whole-body exposure.

UV protection


Light hardening: The habituation effect usually lasts only a few days.


  • PUVA therapy

Prednisolon approx. 0.5-1 mg / kg bw 1x daily, quickly levelling out.

Antihistamines e.g. Xyzal 5 mg 1x daily

Ciclosporin 3-5mg /kg bw short-term.