For Healthcare Professionals Only
Acute urticaria
Acute urticaria is a common disorder of skin with a lifetime prevalence estimated at 20%. Patients with acute urticaria typically present with migrating pruritic edematous papules and plaques of variable size, surrounded by erythema or an area of vasoconstriction (i.e., wheal). They may be intermittent, with the skin returning to normal appearance in less than 24 hours. They result from a variety of causes, including drug reactions, food allergy, systemic disorders, and infection; the underlying cause may be undetermined in many cases. Following discontinuation or avoidance of the inciting agent, the majority of acute reactions resolve within days to weeks. Therefore, therapy is symptomatic and attempts to suppress symptoms until urticaria abates.
Chronic urticaria
Chronic urticaria represents approximately 25% of all cases of urticaria and is defined as urticaria when lasting longer than 6 weeks; the cause is often not found. Chronic urticaria may be idiopathic or found in association with underlying systemic diseases such as infection (bacterial, fungal, parasitic, viral), autoimmune disease (including production of auto-antibodies against the IgE receptor, triggering mast cell degranulation), or drug reaction. Whereas foods may be a relevant trigger for acute urticaria, the role of food allergies in chronic urticaria is controversial; a consistent, reproducible trigger is often not identified. Because chronic urticaria may stem from an underlying systemic illness, it is important to perform a complete history and physical examination and pursue only basic laboratory testing and relevant diagnostic considerations. Although underlying malignancy was previously believed to be a cause of chronic urticaria, prior recommendations for diagnostic malignancy workup are no longer supported by recent evidence. The goal of therapy is to provide relief of symptoms.
Clinical presentation
Juicy pink to erythematous sometimes confluent into plaques, with edema and surrounding vasoconstriction (i.e., wheal).
Clinical Atlas images:
96-1 & 96-3;
96-5 & 96-6;
96-7 & 96-10;
96-11 & 96-16;
96-18
Dermographic urticaria/ dermographism: results from frictional stress on the skin (such as scratching), eliciting rapid onset of urticarial lesions (1-5 minutes).
Clinical Atlas mage
96-21
Other Types of Urticaria
Differential diagnosis
It is imperative to determine whether the patient has urticaria alone or a more systemic presentation with possible progression to angioedema or anaphylaxis. Careful review of symptoms of anaphylaxis, such as tongue, lip, or facial swelling, shortness of breath or wheezing, and diarrhea is necessary. Angioedema is characterized by deep tissue swelling (i.e., dermal or subcutaneous edema), pain more than itching, involvement of mucous membranes, and resolution that is slower than for urticaria (which typically resolve in <24 hours); angioedema typically takes up to 72 hours to resolve.
Clinical Atlas
96-17
Pathophysiology
Initial diagnostic testing
First-line therapy: non-sedating H1-antihistamines (second generation)
Initial therapy
1. Treat with a non-sedating H1 antagonist antihistamine:
2. Consider escalating the dose up to 4-fold dosing after 2 weeks. There is current data supporting that dose-escalation is effective for some, but not all, non-sedating H1 antihistamines.
3. If urticaria is suppressed, treat the patient continually in order to maintain control of the process, with a slow taper once symptoms fully subside.
4. Systemic steroids (such as prednisone) may be necessary for 3-7 days for severe, acute flares.
5. Sedating H1 antagonist antihistamines are no longer recommended as first-line or long-term treatment of urticaria because of adverse effects associated with their use (such as sedation, anticholinergic effects) and due to the high efficacy and wide availability of non-sedating antihistamines.
Subsequent therapy
1. Add a leukotriene inhibitor, like montelukast (such as Singulair) 10 mg q day.
2. There is some evidence to support addition of other agents such as:
3. A regimen with multiple agents in combination may be necessary to control symptoms.
Pitfalls
1. If urticaria is not suppressed by initial doses of an H1 antihistamine, increase the dose to the limit of side effects tolerated by the patient. The majority of acute urticarial reactions will not require use of epinephrine or systemic steroids.
2. Acute urticaria may be a manifestation of systemic anaphylaxis. In such situations, treat the patient rapidly for this potentially fatal disorder.
3. Other systemic disorders may present as acute urticaria. Look for immune complex diseases and the initial phase of viral hepatitis in patients with symptoms not clearly explained by urticaria.
4. Sedation is a frequent complication of some antihistamine therapy, even with some traditionally non-sedating antihistamines, but often resolves with continuation of therapy.
5. Look for drugs that cause or exacerbate urticaria (including such commonly used agents as aspirin and NSAIDS).
Case 1
Clinical atlas
96-3
Initial treatment
Follow-up evaluation at 1 week
Follow-up evaluation at 2 weeks
Case 2
Clinical Atlas images
96-10 & 96-11
Follow-up evaluation at 4 weeks
Khan DA. Chronic urticaria: diagnosis and management. Allergy Asthma Proc 2008;29:439-446.
Peroni A et al. Urticarial lesions: If not urticaria, what else? The differential diagnosis of urticaria. Part I, II. J Am Acad Derm 2010;62:541-570.
Zuberbier T et al. Guideline: Management of urticaria. Allergy 2009;64:1427-1443.
Zuberbier T et al. Guideline: definition, classification and diagnosis of urticaria. Allergy 2009;64:1417-1426.
CONTENT PROVIDED BY:
Disclaimer: The material above has been prepared by Derm101.com. It has not been reviewed by the DermQuest Editorial Board for its accuracy or reliability. Reference to any products, service, or other information does not constitute or imply endorsement, sponsorship, or recommendation by members of the Editorial Board.