Variability
Acute urticaria is by its nature a variable condition with episodes of rash recurring over several days or weeks. However the episodes tend to be irregular and infrequent unless there is repeated exposure to a known trigger factor. In some cases tolerance to the trigger can develop and the condition may resolve fully.
Chronic urticaria may also show some variation in the rash but by definition the effects persist for at least six weeks and often for several years.
