Dermatology, Venereology and Leprosy
Urticaria and Angioedema
Urticaria for MBBS and NEET-PG: transient weals, acute versus chronic, physical urticarias, dermographism, hereditary angioedema and treatment, mapped to NMC codes DR14.
MedNext Academy | 3 min read
Urticaria and Angioedema
Urticaria for MBBS and NEET-PG: transient weals, acute versus chronic, physical urticarias, dermographism, hereditary angioedema and treatment, mapped to NMC codes DR14.
Urticaria and angioedema are common presentations that range from a nuisance itch to life-threatening airway swelling. This chapter covers the mast-cell mechanism of transient weals, the distinction between acute and chronic and physical urticarias, dermographism, the special case of hereditary angioedema, and treatment from antihistamines to adrenaline.
High-yield: Urticaria and Angioedema
- Urticaria, or hives, is characterised by transient itchy weals caused by dermal oedema from histamine release by mast cells.
- An individual weal is short-lived and resolves within 24 hours without leaving a mark, which distinguishes urticaria from vasculitis.
- Angioedema is deeper swelling of the subcutaneous and submucosal tissues and preferentially affects the lips, eyelids and, dangerously, the larynx.
- Urticaria is called acute when it lasts less than six weeks and chronic when it persists beyond six weeks.
- Acute urticaria is often triggered by drugs, foods, infections or insect stings, whereas chronic urticaria is frequently idiopathic or autoimmune.
- Physical urticarias are provoked by stimuli such as pressure, cold, heat, sunlight and water.
- Dermographism is a physical urticaria in which firmly stroking the skin produces a linear weal, and it can be demonstrated at the bedside.
- Hereditary angioedema is due to C1 esterase inhibitor deficiency, presents without weals or itch and does not respond to antihistamines or adrenaline in the usual way.
- Angiotensin-converting enzyme inhibitors are an important drug cause of angioedema through bradykinin accumulation.
- Urticaria with angioedema can be part of anaphylaxis, and airway involvement or systemic features are a medical emergency.
- Second-generation non-sedating antihistamines are the first-line treatment for urticaria, uptitrated as needed.
- A short course of oral corticosteroids may be used for a severe acute flare, but not for long-term control.
- Adrenaline is the immediate treatment for anaphylaxis and life-threatening angioedema with airway compromise.
- Identifying and avoiding the trigger, where one is found, is central to management.
Urticaria and angioedema essentials
- **Weal:** Transient itchy swelling resolving within 24 hours; histamine from mast cells.
- **Acute versus chronic:** Acute under 6 weeks (triggers); chronic over 6 weeks (often idiopathic).
- **Angioedema:** Deeper swelling of lips, eyelids, larynx; airway risk.
- **Treatment:** Non-sedating antihistamines first-line; adrenaline for anaphylaxis.
NMC competencies in this chapter
- **DR14.1:** Aetiology, pathogenesis and classification of urticaria and angioedema
- **DR14.2:** Distinguishing urticaria from other skin lesions
- **DR14.3:** Demonstrating dermographism
- **DR14.4:** Distinguishing angioedema from other skin lesions
- **DR14.5:** Indications and pharmacology of drugs used in urticaria and angioedema
Frequently Asked Questions
How long does a single urticarial weal last?
An individual weal is transient and resolves within 24 hours without leaving a mark. A lesion that lasts longer or heals with bruising suggests urticarial vasculitis rather than ordinary urticaria.
What is the difference between acute and chronic urticaria?
Acute urticaria lasts less than six weeks and often has an identifiable trigger, while chronic urticaria persists beyond six weeks and is frequently idiopathic or autoimmune.
Why is hereditary angioedema different?
It results from C1 esterase inhibitor deficiency, causes swelling without weals or itch, and does not respond to antihistamines or adrenaline in the usual way, needing specific treatment.
What is the first-line treatment for urticaria?
Second-generation non-sedating antihistamines, uptitrated as required, with adrenaline reserved for anaphylaxis and angioedema that threatens the airway.
Continue reading
MBBSAll Dermatology, Venereology and Leprosy chapters
Continue through the Dermatology, Venereology and Leprosy chapter map.
Continue studying Dermatology, Venereology and Leprosy
Explore clinician-written learning resources, structured revision and practice across the MedNext platform.
Open in the MedNext appSee plans

