**3.2 NSAID-induced urticaria/angioedema**

Patients with NSAID-induced urticaria and/or angioedema (NIUA) do not have spontaneous urticaria and/or angioedema, but only the reactions develop after the NSAID intake. NIUA is a multiple NSAID hypersensitivity syndrome and there is cross-reactivity between chemically unrelated NSAIDs. Since patients often start to avoid NSAIDs after their first reaction, this cross-reactivity might not always be clear. Patients can report isolated urticaria, angioedema or a combination of both. A small proportion of patients with NIUA developed chronic spontaneous urticaria after 10 year- period of follow-up [10]. So, there is a certain degree of interrelationship between both phenotypes, NECD and NIUA, and possibly in some patients they represent different stages of the same disease.

All patients with NECD and NIUA show a pattern of multiple reactivity between NSAID, dependent on the level of *in vitro* inhibition potency of COX −1 isoform (**Table 2**).
