Acute and Chronic Urticaria
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At a Glance: AU vs CSU vs CIndU
This table is not intended to replace medical judgment.
Urticaria type | Duration | Defining features | Trigger pattern and etiology | Diagnostic focus | Treatment approaches |
|---|---|---|---|---|---|
| Acute | |||||
Acute Urticaria (AU) | Flares occur for <6 weeks | Acute onset of wheals with or without angioedema. Individual wheals resolve within 24 hours, although new lesions may continue to appear. | May or may not have an identifiable trigger (half of cases are idiopathic). Common triggers include viral infections, medications (NSAIDs, narcotics, PNC, cephalosporins, ACEIs), and foods. | History, physical examination, and review of patient photos if available. Routine diagnostic testing generally unnecessary unless history suggests a specific cause, such as food allergy or environmental allergy (Type 1 hypersensitivity). | Begin with second-generation H1 antihistamines for symptom control. Avoidance of provocational factors if identified. Consider systemic corticosteroids for short-term use in acute cases and emergencies. |
| Chronic | |||||
Chronic Spontaneous Urticaria (CSU) | Flares occur for >6 weeks | Spontaneous wheals with or without angioedema. Individual wheals resolve within 24 hours. | Many cases are idiopathic. Other causes include infection and autoimmune or autoallergic mechanisms. | History, physical examination, and review of patient photos if available. Consider testing if clinically indicated for nonresponders with severe disease or to evaluate for comorbidities (consider CBC with differential, CRP, ESR, thyroid panel). If urticaria lasts longer than 24 hours or leaves postinflammatory hyperpigmentation, consider work-up for urticarial vasculitis. | Begin with second-generation H1 antihistamines: begin at standard dose and uptitrate as per guidelines. If inadequately controlled, FDA-approved options include omalizumab, dupilumab, and remibrutinib. Consider cyclosporine for severe refractory cases. |
Chronic Inducible Urticaria (CIndU) | Flares occur for >6 weeks | Wheals with or without angioedema induced by specific reproducible stimuli (may be a delayed presentation). Individual wheals resolve within 24 hours. | Symptoms reproducibly elicited by defined physical or environmental stimuli. More than one CIndU subtype and/or concomitant CSU may occur. | History, physical examination, and subtype-specific provocation testing. Threshold testing can help characterize disease activity and trigger sensitivity. | Avoidance of provocational factors. Second-generation H1 antihistamines: begin at standard dose and uptitrate as per guidelines. |
ACEI = Angiotensin-converting enzyme inhibitors; AU = Acute urticaria; CBC = Complete blood count; CIndU = Chronic inducible urticaria; CRP = C-reactive protein; CSU = Chronic spontaneous urticaria; ESR = Erythrocyte sedimentation rate; FDA = US Food and Drug Administration; NSAID = Nonsteroidal anti-inflammatory drug; PNC = Penicillin; UV = Ultraviolet
CIndU: Know the Subtypes
Diagnosis is typically confirmed with subtype-specific provocation testing and patient history. For certain subtypes, threshold testing may characterize trigger sensitivity and disease activity.
Subtype | Trigger and clinical features |
|---|---|
Heat urticaria | Direct local heat exposure. Wheals/pruritus occur at the exposed site. Heat sources may include water, sunlight, or radiant heat. |
Cold urticaria | Exposure to cold air, cold or rainy weather, cold water or liquids, and cold surfaces or objects. Wheals and/or angioedema occur at an exposed site after rewarming. Reflex cold urticaria can be life-threatening. Systemic symptoms may occur if large body areas are exposed. |
Solar urticaria | Exposure to sunlight or artificial UV/visible light. Wheals/pruritus develop rapidly on exposed skin, usually within minutes. Phototesting can identify triggering wavelength and threshold. |
Aquagenic urticaria | Water contact, regardless of temperature. Small wheals develop at site of exposure. |
Cholinergic urticaria | Rise in core body temperature, commonly with exercise, eating spicy food, stress, or sweating. Typically causes numerous small 2–3 mm papular wheals. Systemic symptoms may occur. |
Symptomatic dermographism | Shearing or friction; linear wheals develop within minutes after stroking or rubbing the skin. Trigger threshold can be assessed. Remibrutinib is FDA approved for adults with symptomatic dermographism inadequately controlled by H1 antihistamines. |
Delayed pressure urticaria | Sustained pressure (eg, straps, tight clothing, prolonged standing). Swelling develops after a delay, often several hours after exposure. |
Vibratory angioedema | Vibration (eg, power tools or repetitive mechanical stimulus). Localized swelling develops at the exposed site. |
Contact urticaria | Direct skin contact with a triggering substance. Localized wheals arise at the contact site, usually within minutes. Diagnosis guided by history and contact provocation testing when appropriate. Can be immunologic (eg, latex) or nonimmunologic (eg, sorbic acid or cinnamic aldehyde). |
ACEI = Angiotensin-converting enzyme inhibitors; AU = Acute urticaria; CBC = Complete blood count; CIndU = Chronic inducible urticaria; CRP = C-reactive protein; CSU = Chronic spontaneous urticaria; ESR = Erythrocyte sedimentation rate; FDA = US Food and Drug Administration; NSAID = Nonsteroidal anti-inflammatory drug; PNC = Penicillin; UV = Ultraviolet
v1 – October 2026 – Copyright 2026. Nicholas Brownstone, MD, and Jill Cowan, PA-C.
DISCLAIMER: This chart is for reference only and not to be substituted for clinical judgment. The authors are not responsible for treatment decisions or outcomes based on the information in this chart.