Angioedema with and without urticaria

01OverviewDefinition, clinical context and the essential points that orientate the chapter.

Take a minute-by-minute history: site first affected, speed, itch, wheals, flushing, breathing, hypotension, abdominal pain, duration and response to treatment. Review ACE inhibitors, oestrogen exposure, NSAIDs and recent new drugs. Ask about dental procedures, trauma, family episodes and unexplained abdominal admissions.

The phenotype determines investigation. A single episode with classic urticaria may need no complement testing. Recurrent non-urticarial swelling warrants C4 and C1-inhibitor level and function; low C1q may support acquired disease in appropriate specialist assessment. Tryptase is relevant after suspected anaphylaxis, not as a general angioedema screen.

Clinical decisions in Angioedema with and without urticaria depend on trajectory and consequence. Re-examine evolving skin, repeat focused systemic assessment when the patient changes, and reconcile every result with morphology and timing; a normal early test cannot neutralise worsening pain, mucosal injury or organ dysfunction.

Key points

Angioedema is deeper swelling of skin or mucosa; eyelids and lips are common, but tongue, larynx and bowel involvement determine danger.
Wheals, itch, rapid onset and an obvious allergen support mast-cell disease; absence of wheals, slower onset and abdominal attacks support bradykinin disease.
ACE-inhibitor angioedema may occur after years of treatment; stop the ACE inhibitor permanently and document it clearly.
For recurrent angioedema without wheals, measure C4 plus C1-inhibitor antigenic level and function, ideally with specialist interpretation and repeat confirmation.
Normal oxygen saturation does not exclude a threatened upper airway, and blood sampling must never delay airway management.
Antihistamines and corticosteroids are not effective disease-specific treatments for bradykinin angioedema; use the specialist emergency plan.
Angioedema with and without urticaria must be assessed by lesion duration, onset, distribution, symptoms, mucosal findings, systemic physiology and the full medicine timeline rather than by colour alone.
For Angioedema with and without urticaria, document the working diagnosis, excluded emergencies, uncertain culprit or trigger, treatment response and the exact safety-net given.

02AetiologyUnderlying causes, associations and risk factors, with why each one matters.

Mast-cell mediator release

Allergens, spontaneous urticaria and some medicines release histamine and related mediators, usually causing rapid itchy swelling with wheals or other anaphylaxis features.

Bradykinin accumulation

ACE inhibition, hereditary C1-inhibitor deficiency and acquired complement disorders increase bradykinin, producing slower non-itchy swelling without ordinary wheals.

Local and systemic mimics

Dental infection, cellulitis, venous obstruction, contact dermatitis, thyroid disease and dependent oedema can resemble angioedema but follow different anatomical and temporal patterns.

03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.

1
Deep vascular permeability
Mediator-driven leakage in deep dermis, subcutis and submucosa creates poorly demarcated swelling that feels tight or painful rather than forming a superficial wheal.
2
Histamine pathway
Mast-cell disease often evolves over minutes, accompanies itch and urticaria, and improves with H1 blockade; anaphylaxis requires adrenaline because multiple organs are threatened.
3
Bradykinin pathway
Excess bradykinin increases vascular permeability over hours, commonly affects bowel and airway, lacks wheals and responds poorly to antihistamines, corticosteroids and adrenaline.
4
Complement consumption
C1-inhibitor deficiency or dysfunction permits uncontrolled contact-system activation; C4 often falls during attacks but diagnostic confirmation needs antigenic and functional assays.

04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.

Threatened upper airwayRed flag

Tongue, floor-of-mouth or laryngeal swelling, altered voice, drooling or stridor requires immediate airway expertise and repeated examination.

Histaminergic phenotype

Rapid itchy lip or eyelid swelling with wheals, flushing or allergen exposure favours mast-cell activation and may be part of anaphylaxis.

Bradykinin phenotype

Slower non-pruritic swelling without wheals, poor antihistamine response and recurrent abdominal pain suggests ACE-inhibitor or C1-inhibitor-mediated disease.

Abdominal attack

Severe episodic cramping, vomiting and ascites-like fluid shift can be bowel-wall angioedema, particularly with a matching family or swelling history.

Red flags requiring action

Voice change, stridor, drooling, dysphagia, tongue swelling, respiratory distress, hypotension, rapid progression or previous difficult airway requires immediate hospital care.

05InvestigationsWhat to request, why it matters and how to interpret it.

Investigation order

Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.

01
Serial ABC and oral-airway examinationFirst step
Why
Detect progression before obstruction becomes physiologically obvious.
Interpretation and limitations
Inspect tongue and floor of mouth without provoking distress; voice change and increasing swelling can precede desaturation.
02
C4 and C1-inhibitor level and function
Why
Assess suspected hereditary or acquired bradykinin angioedema.
Interpretation and limitations
Abnormal results require repeat and specialist interpretation; a normal C4 between attacks does not safely replace full assays when suspicion remains high.
03
Mast-cell tryptase after suspected anaphylaxis
Why
Support retrospective confirmation of systemic mast-cell activation.
Interpretation and limitations
Take samples at guideline-defined times after treatment begins; a normal result does not exclude anaphylaxis and must not delay adrenaline.
04
Medicine and family pedigree review
Why
Identify ACE-inhibitor exposure, oestrogen effects and inherited recurrence.
Interpretation and limitations
ACE-inhibitor latency may be years and no family history does not exclude hereditary disease because penetrance and de novo variants vary.
05
Targeted imaging or infection tests
Why
Evaluate focal persistent swelling or an alternative abdominal emergency.
Interpretation and limitations
Imaging can show bowel-wall oedema but is nonspecific; investigate surgical, dental and infectious causes when phenotype is discordant.

06Differential diagnosisRealistic alternatives and the features that help distinguish them.

Anaphylaxis

Angioedema with acute airway, breathing or circulatory compromise is treated as anaphylaxis regardless of whether a trigger or wheal is identified.

Hereditary angioedema

Recurrent non-urticarial swelling, severe abdominal attacks, family history or onset when young supports C1-inhibitor deficiency, although de novo variants occur.

ACE-inhibitor angioedema

New non-itchy facial, oral or tongue swelling can begin after years of uneventful ACE-inhibitor treatment and mandates permanent withdrawal.

Infection and obstruction

Unilateral painful erythema, fever, dental symptoms, neck mass or persistent dependent swelling suggests infection or impaired venous or lymphatic drainage.

Additional chapter-specific clues

Infectious mimic

Unilateral warmth, dental pain, fever, purulence or a persistent focal mass is not typical angioedema and needs urgent alternative assessment.

07ManagementImmediate care, first-line treatment, alternatives and escalation.

01Airway or anaphylaxis emergencyStabilise before classifying mediatorFirst stepSwelling affects tongue or airway, progresses rapidly, or accompanies breathing or circulation compromise.

1Call anaesthetic and resuscitation support, position according to physiology, provide high-flow oxygen and monitor continuously while planning a difficult airway.
2Give intramuscular adrenaline promptly when anaphylaxis is suspected and repeat after five minutes if ABC compromise persists.
3Use disease-specific hereditary-angioedema rescue treatment immediately when a confirmed patient’s plan indicates it, without allowing classification uncertainty to delay airway control.

02Likely mast-cell angioedemaTreat histamine pathway and find immediate triggersSwelling is rapid and itchy, accompanies wheals, or follows a plausible allergen without progressive airway compromise.

1Use a non-sedating H1 antihistamine for uncomplicated symptoms, stop the trigger when identifiable and observe for evolving systemic features.
2If anaphylaxis occurred, follow tryptase, observation and allergy-referral guidance and supply auto-injectors when risk assessment indicates.
3Avoid broad allergy testing without a specific exposure history because sensitisation does not establish causation.

03Likely bradykinin angioedemaRemove ACE inhibition and confirm complement phenotypeEpisodes lack wheals, develop over hours, involve abdomen or recur despite antihistamines.

1Stop any ACE inhibitor permanently, record the reaction in prescribing systems and choose future blood-pressure therapy with appropriate review.
2Request C4 and C1-inhibitor antigen and function, then refer immunology for diagnostic confirmation, family testing and an individual attack plan.
3For established hereditary disease, coordinate procedures, pregnancy and long-term prophylaxis with the specialist service rather than improvising corticosteroid cover.

Key medicines and prescribing safety2 treatments · regimens, roles and cautions

Treats airway, breathing and circulation compromise when angioedema forms part of anaphylaxis; it must not be delayed for antihistamines or tests.

Intramuscular adrenaline 1 mg/mL solution

For adult anaphylaxis give 500 micrograms intramuscularly, equal to 0.5 mL of 1 mg/mL solution, into the anterolateral thigh; repeat after five minutes if ABC problems persist.

Use the intramuscular route initially, monitor continuously, avoid inadvertent intravenous bolus, and seek expert support for refractory anaphylaxis or a threatened difficult airway.

Reduces itch, wheals and uncomplicated mast-cell-mediated swelling but does not replace adrenaline for anaphylaxis or treat bradykinin disease.

Cetirizine 10 mg tablets

Adults and adolescents aged 12 years and over take 10 mg orally once daily, adjusted for renal impairment according to product guidance.

Somnolence, alcohol, driving, renal function, pregnancy and breastfeeding need review; a non-response should trigger mediator reassessment rather than automatic repeated dosing.

08ComplicationsImportant consequences, why they occur and why they matter clinically.

Airway obstruction

Progressive tongue and laryngeal oedema can make ventilation and intubation difficult, so early expert airway involvement is safer than waiting for stridor.

Unnecessary repeated medication

Treating bradykinin episodes repeatedly with antihistamines or corticosteroids delays effective specialist rescue therapy and adds avoidable adverse effects.

Recurrent abdominal morbidity

Bowel-wall oedema causes severe colicky pain, vomiting and fluid shift and can lead to unnecessary surgery before hereditary disease is recognised.

Family risk

Unrecognised hereditary angioedema leaves relatives without testing, trigger counselling, procedural prophylaxis or access to effective on-demand treatment.

09Monitoring and follow-upTreatment response, safety checks and longer-term review.

Record episode site, duration, wheals, abdominal symptoms, suspected trigger and response to adrenaline or antihistamine for angioedema classification.
Verify permanent ACE-inhibitor discontinuation across primary, secondary and pharmacy records after a suspected ACE-inhibitor episode.
For confirmed hereditary disease, review rescue availability, expiry, self-administration skill, procedure plans and family screening.
At every review of Angioedema with and without urticaria, record lesion evolution, new mucosal or systemic features, medicine changes, treatment adherence and adverse effects.
Give a named route for urgent reassessment if breathing, circulation, fever, skin pain, blistering, facial swelling, reduced urine output or other organ symptoms develop during Angioedema with and without urticaria.

10Special situationsVariants, exceptions and circumstances that change the usual approach.

Wheals are a pathway clue

Ordinary urticaria strongly favours mast-cell mediation, whereas bradykinin angioedema characteristically occurs without wheals.

ACE latency can be long

Years of previous tolerance do not make an ACE inhibitor innocent when new tongue or facial swelling appears.

Abdominal disease can dominate

Some hereditary attacks cause severe bowel symptoms without visible peripheral swelling and mimic an acute surgical abdomen.

Oxygen saturation is late

A patient can have dangerous supraglottic swelling while saturation remains normal, making voice and anatomy crucial.

Response is supportive evidence

Failure of antihistamine and corticosteroid treatment supports but does not by itself prove a bradykinin mechanism.

11Common pitfallsFrequent interpretation and management errors.

01
Waiting for stridor or desaturation before requesting expert airway support.
02
Continuing an ACE inhibitor because the first angioedema episode occurred years after it was started.
03
Calling non-urticarial recurrent swelling an allergy and ordering indiscriminate food panels.
04
Using a normal single C4 result to dismiss a convincing hereditary angioedema history.
05
Assuming adrenaline treats the bradykinin mechanism while overlooking the need for airway care and disease-specific rescue.