The definition of CSU and classification of chronic urticaria.

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CSU is defined as the spontaneous appearance of wheals, angioedema or both, lasting for more than 6 weeks. The cause is unknown.

Urticaria may be classified into different subtypes based on duration and cause:

Classifying chronic urticaria¹

Adapted from Zuberbier T et al. 2018.¹

Reference

1. Zuberbier T et al. Allergy 2018;73(7):1393–1414.