DR14.1-3 | Urticaria Angioedema — Glossary

Urticaria in which the eruption lasts less than 6 weeks; usually triggered by an infection, drug, or food and typically self-limiting.

The first-line, life-saving drug for anaphylaxis and angioedema with airway compromise, given intramuscularly (0.5 mg of 1:1000 in an adult) into the anterolateral thigh.

A systemic, potentially fatal hypersensitivity reaction that may accompany urticaria/angioedema, featuring airway compromise, bronchospasm, and/or hypotension; treated immediately with intramuscular adrenaline.

Oedema of the deep dermis and subcutaneous or submucosal tissue, producing diffuse, less itchy, longer-lasting swelling that favours the lips, eyelids, tongue, larynx, and genitalia.

A local nerve reflex, not involving the central nervous system, that causes arteriolar dilation around a stimulated area; responsible for the red flare of the triple response.

Deep swelling driven by accumulation of the vasoactive peptide bradykinin rather than histamine; seen in ACE-inhibitor-induced and hereditary angioedema, it presents without wheals and does not respond to antihistamines.

An inducible urticaria producing small punctate wheals on sweating, heat exposure, or exertion.

Chronic urticaria in which wheals are reproducibly provoked by a specific physical stimulus (e.g. stroking, cold, pressure, exertion, sunlight).

Chronic urticaria occurring without a consistent identifiable external trigger; frequently has an underlying autoimmune mechanism.

Urticaria in which wheals (with or without angioedema) recur on most days for 6 weeks or longer.

An inducible urticaria in which firmly stroking or scratching the skin produces a linear wheal-and-flare response along the line of contact.

A calibrated instrument that applies a defined, reproducible pressure to the skin to elicit dermographism in a standardised way; bedside alternatives include the wooden end of a swab or a tongue depressor edge.

A negative test in a patient who truly has dermographism, classically caused by recent antihistamine use suppressing the histamine-driven wheal; the test should be repeated after a drug-free interval.

An inherited bradykinin-mediated angioedema caused by C1-esterase inhibitor deficiency; characterised by recurrent deep swelling without urticaria, with low C4 and C1-inhibitor levels.

The principal mediator released by mast cells; acting on H1 receptors it causes vasodilatation, increased vascular permeability, and itch — the three components of a wheal.

Urticaria in which wheals are reproducibly provoked by a specific physical stimulus such as stroking, cold, pressure, exertion, or sunlight; dermographism is its commonest type.

A tissue-resident immune cell whose granules store preformed histamine; its degranulation, releasing histamine and other mediators, is the central event in urticaria.

A monoclonal anti-IgE antibody used as add-on therapy for chronic spontaneous urticaria that remains refractory to up-dosed antihistamines.

A bedside test in which a physical stimulus is applied to reproduce a patient's lesion — here, a firm skin stroke — to confirm an inducible urticaria.

Itch — the symptom whose presence or absence distinguishes symptomatic (treatable) dermographism from asymptomatic simple dermographism.

The second component of the triple response — a brighter zone of redness spreading on either side of the stroke line, produced by an axon reflex that dilates nearby arterioles.

The first component of the triple response — a reddening along the line of the stroke within seconds, caused by local capillary dilation.

Non-sedating histamine H1-receptor blockers (e.g. cetirizine, levocetirizine, fexofenadine, loratadine, bilastine) — the recommended first-line treatment for urticaria, preferred over sedating first-generation agents.

A normal variant, present in about 5% of healthy people, in which stroking the skin produces a wheal but with no itch or symptoms; requires no treatment.

The clinically significant form of dermographism in which the provoked wheals are itchy and troublesome; warrants treatment.

The orderly sequence of skin changes following a firm stroke: an initial red line (capillary dilation), a spreading red flare (axon reflex), and finally a raised wheal (histamine-mediated oedema).

A condition characterised by recurrent, intensely itchy wheals caused by oedema of the superficial dermis; each individual wheal is transient, lasting less than 24 hours.

A small-vessel (leukocytoclastic) vasculitis whose lesions resemble wheals but persist beyond 24 hours, are painful, and resolve with bruising or pigmentation; confirmed by skin biopsy.

The defining lesion of urticaria — a raised, well-demarcated, pink or pale swelling with a surrounding red flare, produced by superficial dermal oedema; itchy and short-lived (<24 hours).