Chronic urticaria is defined as urticaria
that persists for
longer than 6 weeks. In most of the cases of chronic urticaria
, the underlying pathology is idiopathic i.e. it is not linked to any cause. It is essential to rule out the presence of serious illnesses of which recurring hives can be a symptom. Examples are hepatitis, hyperthyroidism, lymphomas, collagen vascular diseases etc.
The most potent antihistamine for urticaria is probably the anti-depressant doxepin.