Assessment of urticaria

sudden onset pruritic rash for <6 weeks, with unknown or suspected precipitating factor (e.g., associated with ingesting a specific food or medication, preceding history of upper respiratory tract infection)

pruritic, pale, blanching swellings of the superficial dermis that last for up to 24 hours, lesions may be small, large, giant, oval, or annular, no overlying flaking or scaling; may be associated features of angio-oedema (swelling of the deeper dermis and tissues, e.g., mucosal surfaces); may be signs associated with an aetiology

sudden onset pruritic rash for ≥6 weeks, with unknown or suspected precipitating factor (e.g., associated with ingesting a specific food or medication, preceding history of upper respiratory tract infection); no history of inducibility; majority have no history of any underlying aetiology

pruritic, pale, blanching swellings of the superficial dermis that last for up to 24 hours, lesions may be small, large, giant, oval, or annular, no overlying flaking or scaling; may be associated features of angio-oedema (swelling of the deeper dermis and tissues such as mucosal surfaces); may be signs associated with an aetiology

sudden onset pruritic rash persisting for ≥6 weeks, may be history of inducibility of the rash by physical factors such as heat, cold, pressure, vibration, water, and sunlight

pruritic, pale, blanching swellings of the superficial dermis that last for up to 24 hours, lesions may be small, large, giant, oval, or annular, with no overlying flaking or scaling; may be dermatographism (whealing of skin minutes after superficial sharp scratch)

mostly macules and papules of trunk and extremities, commonly with centrifugal spread; onset 1 to 2 weeks after start of new medication, possibly sooner with repeat challenges; lesions do not resolve with antihistamines

lesions may not blanch fully, post-inflammatory discolorations

localised lesions on exposed areas of skin, often after outdoor exposure; recent insect bites; other family members often affected

nodules of the lower extremities in the summer suggestive of mosquito bites, similar lesions after ant/bedbug/scabies/flea bites (type 4 reaction); accompanying angio-oedema suggestive of Hymenoptera allergy (type 1 reaction)

rash occurs concurrently with symptoms of viral infection but can precede symptoms or occur during the resolution of the viral illness

rash can present in various forms including urticarial, maculopapular, morbilliform, scarlatiniform or dermatomal; rash can also be widespread or localised

presents with pruritus; may have history of concomitant allergic rhinitis and/or asthma; may have family history of atopic dermatitis

presents with xerosis (dry skin), erythema, scaling, vesicles, papules, keratosis pilaris, excoriations, lichenification, hypopigmentation; in infants affects cheeks, forehead, scalp, and extensor surfaces; in children involves flexures, particularly the wrists, ankles, and antecubital and popliteal fossae;​​ chronic atopic dermatitis often affects the neck, upper back, and arms, as well as the hands and feet;​​​​ may also have dermatographism (whealing of skin minutes after superficial sharp scratch)

recurrent dermatitis in areas of exposure to potential allergens: for example, skin care products or substances used for hobbies or professional activities

lesions at site of jewelry/belt buckle/button/watch (nickel allergy), eyelid (nail polish allergy), forehead and both eyelids (shampoo allergy)

repeated irritant exposure: for example, diapers or chronic handwashing

eczematous lesions: lichenified, hyperkeratotic (scaly), erythematous plaques; patterns suggestive of exposures (e.g., hands [detergents and household cleansers] or buttocks [diapers])

onset of rash usually after infection with virus (e.g., herpes), bacteria, mycoplasma, or after drugs (e.g., penicillin)

rash consisting of erythematous papules with central clearing (target lesions)

history of medication use such as allopurinol, sulfa drugs, and non-steroidal anti-inflammatory drugs (NSAIDs)

initial skin lesions similar to erythema multiforme rash (erythematous papules with central clearing [target lesions]) but progresses into widespread areas of erythema; bullous formation and necrosis of the epidermal layer may occur, oral mucosities usually present and other mucosal surfaces may be involved; ocular involvement usually includes conjunctivitis

history of trauma to sympathetic and parasympathetic fibres around parotid gland such as from forceps birth

swelling and erythema in facial area after eating spicy or sour foods

common age of onset 60-70 years, may have prodromal non-bullous phase of pruritus and non-bullous rash (may be urticarial), subsequent development of blisters; rash affects face, hands, feet and genitalia; drugs commonly implicated (e.g., furosemide, non-steroidal anti-inflammatory drugs [NSAIDs], captopril, penicillamine, and systemic antibiotics); heals spontaneously

large, tense, sub-epidermal bullae in groin, axillae, trunk, thighs, and flexor surfaces of forearms, often erythematous or urticarial plaques, some with localised disease on shins, bullae and erosions heal spontaneously, absent Asboe-Hansen sign (extension of a blister to adjacent unblistered skin when pressure is put on the top of the bulla)

itching, swelling and blistering of the affected skin, particularly when it is rubbed or scratched

single/multiple/diffuse swellings/pigmented papules urticating with pressure (Darier sign) and blistering; lesions persist for longer than 24 hours and do not blanch with pressure on the skin, lesions leave a pigmented area after resolution; in adults also small tan/brown papules with telangiectasias

pruritic skin lesions, lesion described as 'burning' sensation or pain, accompanied by diarrhoea, wheezing, bone pain (adults); polymyxin B increases swelling/localised blistering of lesions; occasionally in adults: symptoms of mast cell leukaemia (e.g., pruritus, fatigue, wasting, fever, chills, night sweats and other influenza-like symptoms, swollen/bleeding gums, excess bleeding/bruising, headache, frequent infections, swollen tonsils)

single/multiple/diffuse swellings/pigmented papules urticating with pressure (Darier sign) and blistering; lesions persist for longer than 24 hours and do not blanch with pressure on the skin, lesions leave a pigmented area after resolution; in adults also small tan/brown papules with telangiectasias; rarely, doughy skin; lymphadenopathy, hepatosplenomegaly

recurrent episodes of anaphylaxis or recurrent episodes of other acute, severe symptoms of mast cell activation affecting at least two organ systems; acute-onset cardiovascular symptoms (e.g., dizziness, palpitations, syncope/pre-syncope); acute-onset skin symptoms (e.g., flushing, pruritus, swelling); acute-onset respiratory/naso-ocular symptoms (e.g., dyspnoea, cough, conjunctival injection, nasal congestion, sneezing); acute-onset gastrointestinal symptoms (e.g., abdominal cramps, nausea, vomiting, diarrhoea); history of allergic or other trigger (e.g., antibiotics, non-steroidal anti-inflammatory drugs, opioids) for acute episodes (secondary mast cell activation syndrome); history of urticaria pigmentosa (primary mast cell activation syndrome)

variable signs dependent on which organ systems are involved; may include skin changes (e.g., erythema, oedema, eczematous rash, urticaria, angio-oedema) inspiratory stridor, wheeze, tachycardia, hypotension, splenomegaly, hepatomegaly, epigastric tenderness, laryngeal oedema

often painful, recurrent lesions lasting longer than 24 hours; may be recent ingestion of drugs (e.g., potassium iodide, fluoxetine, non-steroidal anti-inflammatory drugs); arthralgias, arthritis, and constitutional symptoms (e.g., malaise, fever, Raynaud phenomenon, abdominal pain, diarrhoea, and symptoms of pulmonary obstructive disease); symptoms of associated systemic disease

crops of lesions, incomplete blanching on diascopy or dermoscopy, post-inflammatory discolorations of resolved lesions; joint swellings; signs of associated systemic disease

onset during or up to 1 hour after blood transfusion; usually mild symptoms (e.g., fever, hypotension, wheezing, anxiety)

usually no differentiating examination findings; rarely, generalised bleeding tendency as late complication

onset 7 to 10 days after injection of protein or drug; earliest symptoms: fever, malaise, headache; subsequently: rash at site of injection or symmetrically spreading from abdomen, joint pain, oedema, GI symptoms (nausea, vomiting, abdominal pain)

urticaria of several weeks duration, joint swellings (knees, ankles, shoulders, wrists, spine, temporomandibular joint), lymphadenopathy

group of autoinflammatory conditions: cold-induced urticaria, Muckle-Wells syndrome, neonatal multi-system inflammatory disease, with increasing severity, with recurrent episodes of inflammation over months/years without infection and malignancy; age of onset usually by 6 months, symptoms and severity depend on specific condition but may include periodic fevers, rash, joint pain, headache, nausea, painful red eyes (conjunctivitis, uveitis), severe episodes of pain at various anatomical sites, e.g., abdomen, chest (serositis), episodes of headache, photophobia, neck stiffness (meningitis); progressive deafness (with Muckle-Wells syndrome and neonatal multi-system inflammatory disease) and subsequently features of amyloidosis

skin manifestations usually include urticarial eruptions that may be cold-induced, usually migratory and widespread; signs and severity depend on specific condition but may include fever, joint tenderness and swelling (arthritis), red painful eyes (conjunctivitis, uveitis), abdominal tenderness, and features of meningitis, bony overgrowth particularly of knees (neonatal multi-system inflammatory disease)

history of exposure of pre-disposed host to a medication, food product, or insect bite; sudden dyspnoea and wheezing, choking sensation, voice changes, tongue and/or lip swelling, rash, and itching, swollen eyelids, agitation, anxiety, impending sense of doom (angor animi), nausea, vomiting, and diarrhoea may be present

rapidly progressive signs, prolonged expiratory phase, signs of bronchospasm (e.g., audible wheeze, use of accessory muscles), tachycardia, hypotension, facial and tongue oedema, cutaneous manifestations (erythematous confluent rash or itchy urticarial wheals, angio-oedema), flushing, rhinitis, inspiratory stridor, syncope, delirium, coma