Background The etiology of urticaria is often difficult to determine. Howev
er, in case of repeated circumsance-connected urticaria, the reason may be
easily clarifyable.
Case A 51-year-old healthy woman repeatedly experienced occupational hand u
rticaria when handling fish food. An unexpected reason for the urticaria wa
s found in that the fishfood contained histamine as a "contaminant".
Conclusions In fishfood batches, biological degradation can produce histami
ne and possibly other toxic substances that can lead to occupational health
problems.