# Chronic spontaneous urticaria
**Chronic spontaneous urticaria** (CSU) is a skin disease in which itchy wheals (hives), angioedema (deep swelling), or both appear spontaneously for six weeks or longer without an identifiable external trigger.[1](https://jamanetwork.com/journals/jama/fullarticle/2824115) It is the most common subtype of chronic urticaria, accounting for roughly 60 to 90 percent of cases, and is driven by activation of mast cells in the skin.[2](https://link.springer.com/article/10.1007/s13555-024-01173-5) • [3](https://www.jacionline.org/article/S0091-6749(22)00545-0/fulltext)
| Key fact | Detail |
|---|---|
| Definition | Spontaneous itchy wheals, angioedema, or both for 6 weeks or longer without an external trigger[1](https://jamanetwork.com/journals/jama/fullarticle/2824115) |
| Prevalence | Approximately 1% of the global population (about 80 million people); diagnosed prevalence 0.92% in the EU5[1](https://jamanetwork.com/journals/jama/fullarticle/2824115) • [4](https://www.ovid.com/journals/jeadv/fulltext/10.1111/jdv.20772~prevalence-treatment-and-burden-of-chronic-spontaneous) |
| Who is affected | About 70% female, most commonly women aged 30 to 50; fewer than 15% of patients are 19 or younger[1](https://jamanetwork.com/journals/jama/fullarticle/2824115) |
| Duration | Symptoms last at least 3 years in about 66% of patients; remission in 17% at 1 year, 45% at 5 years, 73% at 20 years[1](https://jamanetwork.com/journals/jama/fullarticle/2824115) • [2](https://link.springer.com/article/10.1007/s13555-024-01173-5) |
| First-line treatment | Standard-dose second-generation H1 antihistamine; response in about 40% of patients[5](https://pmc.ncbi.nlm.nih.gov/articles/PMC8457139/) • [1](https://jamanetwork.com/journals/jama/fullarticle/2824115) |
| Third-line options | Omalizumab 300 mg every 4 weeks, or off-label cyclosporine 4–5 mg/kg per day[5](https://pmc.ncbi.nlm.nih.gov/articles/PMC8457139/) |
| Cure | No curative treatment exists; approved therapies control symptoms and do not appear to change the disease course[6](https://onlinelibrary.wiley.com/doi/full/10.1111/all.15603) |
## Definition and classification
CSU is distinguished from the chronic inducible urticarias (CIndU) by the absence of a specific external trigger. In inducible subtypes such as cold, heat, or dermographism (wheals from stroking the skin), wheals appear only in response to a defined stimulus and are often of shorter duration, typically one hour or less.[1](https://jamanetwork.com/journals/jama/fullarticle/2824115) CSU wheals, by contrast, arise unprovoked. Dermographism can co-occur with CSU, so the presence of an inducible component does not exclude the diagnosis.[2](https://link.springer.com/article/10.1007/s13555-024-01173-5)
The boundary with urticarial vasculitis matters clinically: vasculitic wheals usually last more than 24 hours and resolve with bruising or postinflammatory hyperpigmentation, whereas CSU wheals are shorter-lived and leave no marks.[1](https://jamanetwork.com/journals/jama/fullarticle/2824115)
## Signs and symptoms
The core lesions are itchy, transient wheals. In one large review, 57% of patients develop only wheals, 37% develop wheals and angioedema, and 6% develop angioedema alone.[1](https://jamanetwork.com/journals/jama/fullarticle/2824115) About two-thirds of patients report systemic complaints such as joint pain and fatigue.[2](https://link.springer.com/article/10.1007/s13555-024-01173-5)
Disease activity and control are measured with patient-reported instruments. The weekly urticaria activity score (UAS7) records daily wheal count and itch over seven days to track activity and treatment response; the angioedema activity score (AAS), chronic urticaria quality of life questionnaire (CU-Q2oL), angioedema quality of life questionnaire (AE-QoL), and angioedema control test (AECT) cover the other dimensions.[2](https://link.springer.com/article/10.1007/s13555-024-01173-5) The Urticaria Control Test (UCT), developed in 2014, is a four-question retrospective survey over the previous four weeks, scored 0 to 16.[7](https://www.e-aair.org/pdf/10.4168/aair.2025.17.5.531) A UCT score of 16 means complete control, 12 to 15 means well-controlled disease, and below 12 means poor control or nonresponse to treatment.[1](https://jamanetwork.com/journals/jama/fullarticle/2824115)
## Causes and mechanisms
CSU is a mast cell–driven disease: activation of skin mast cells and release of their mediators produce the wheals and angioedema.[3](https://www.jacionline.org/article/S0091-6749(22)00545-0/fulltext) Two autoimmune mechanisms have been dissected. In type I autoimmune (autoallergic) CSU, patients produce IgE antibodies against their own proteins, such as thyroid peroxidase or IL-24, in contrast to the IgE directed at external allergens seen in allergic disease.[1](https://jamanetwork.com/journals/jama/fullarticle/2824115) In type IIb autoimmune CSU, IgG autoantibodies target IgE or the high-affinity IgE receptor FcεRI on mast cells and basophils, directly activating them.[3](https://www.jacionline.org/article/S0091-6749(22)00545-0/fulltext)
How many patients are truly autoimmune is contested. The JAMA review states that autoimmune endotypes account for more than 50% of patients, with the nonautoimmune endotype under 35%.[1](https://jamanetwork.com/journals/jama/fullarticle/2824115) A Journal of Allergy and Clinical Immunology review reports type IIb autoimmune CSU in fewer than 10% of patients when strict criteria are used (triple positivity of the autologous serum skin test, immunoassays for IgG autoantibodies, and basophil activation tests), and a 2024 Lancet seminar gives a range of 8 to 40%.[3](https://www.jacionline.org/article/S0091-6749(22)00545-0/fulltext) • [8](https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(24)00852-3/fulltext) The spread reflects different definitions and diagnostic criteria rather than a settled figure.
Features that suggest autoimmune CSU include female sex, symptoms more than 5 days per week, angioedema, nocturnal symptoms, low eosinophil counts (below 0.05 × 109/L), low basophil counts (below 0.01 × 109/L), low total IgE (below 30–43 IU/mL), and high IgG anti–thyroid peroxidase levels (34 kU/L or more).[1](https://jamanetwork.com/journals/jama/fullarticle/2824115) Type IIb disease is further characterized by higher severity, concomitant autoimmune diseases, poor response to antihistamines and omalizumab, and a good response to cyclosporine.[3](https://www.jacionline.org/article/S0091-6749(22)00545-0/fulltext)
Several factors can exacerbate disease activity: stress, nonsteroidal anti-inflammatory drugs (NSAIDs), and viral infections of the respiratory tract.[1](https://jamanetwork.com/journals/jama/fullarticle/2824115) Comorbidities include chronic inducible urticaria (more than 10% of patients), autoimmune thyroiditis (about 20%), metabolic syndrome (6% to 20%), anxiety (10% to 31%), and depression (7% to 29%).[1](https://jamanetwork.com/journals/jama/fullarticle/2824115)
## Diagnosis
The international EAACI/GA²LEN/EuroGuiDerm/APAAACI guideline workup is deliberately limited: a comprehensive medical history, physical examination, and basic tests consisting of a differential blood count, [C-reactive protein](https://www.edgepedia.org/c-reactive-protein) and/or erythrocyte sedimentation rate, and, for patients under specialist care, total IgE and IgG anti-TPO.[2](https://link.springer.com/article/10.1007/s13555-024-01173-5) There are no distinguishing diagnostic biomarkers for CSU; additional laboratory tests serve to identify endotype and prognosis rather than to make the diagnosis.[2](https://link.springer.com/article/10.1007/s13555-024-01173-5)
Differential diagnoses to exclude include urticarial vasculitis, mastocytosis, [mast cell activation syndrome](https://www.edgepedia.org/mast-cell-activation-syndrome), autoinflammatory syndromes such as cryopyrin-associated periodic syndromes or Schnitzler's syndrome, bradykinin-mediated angioedema, hereditary angioedema, and [ACE inhibitor](https://www.edgepedia.org/ace-inhibitor)–induced angioedema. In patients with angioedema only, bradykinin-mediated and hereditary angioedema should be ruled out. [Skin biopsy](https://www.edgepedia.org/skin-biopsy) is performed only when a condition other than CSU is suspected.[2](https://link.springer.com/article/10.1007/s13555-024-01173-5)
CSU itself is not associated with anaphylaxis, and the fatal laryngeal swelling seen in hereditary or ACE inhibitor–induced angioedema has not been reported in CSU.[1](https://jamanetwork.com/journals/jama/fullarticle/2824115)
## By the numbers
Prevalence estimates differ by method. The JAMA review gives approximately 1% of the global population, about 80 million patients, with an incidence of 0.10 to 2.43 per 1000 person-years.[1](https://jamanetwork.com/journals/jama/fullarticle/2824115) A JAMA Dermatology synopsis gives 0.6% to 0.7% globally.[9](https://jamanetwork.com/journals/jamadermatology/article-abstract/2840148) Point prevalence is higher in adults than children (0.02–2.7% versus 0.1–0.9%).[2](https://link.springer.com/article/10.1007/s13555-024-01173-5) In the 2020 EU5 National Health and Wellness Survey of 62,319 respondents, 1.7% reported chronic urticaria symptoms in the past 12 months (667 with CSU), and diagnosed CSU prevalence was 0.92%, ranging from 0.76% in France and 0.79% in Germany and the UK to 1.3% in Italy.[4](https://www.ovid.com/journals/jeadv/fulltext/10.1111/jdv.20772~prevalence-treatment-and-burden-of-chronic-spontaneous)
The disease is long-lasting. About 86% of patients are diagnosed with moderate-to-severe disease; children present with lower rates of angioedema (19% versus 60%) and shorter disease duration (5 versus 12 months) than adults.[2](https://link.springer.com/article/10.1007/s13555-024-01173-5) Progression from acute urticaria (six weeks or less) to CSU is 8% or lower in most studies.[1](https://jamanetwork.com/journals/jama/fullarticle/2824115) Cumulative remission estimates are 17% at 1 year, 45% at 5 years, and 73% at 20 years, so more than half of patients are still affected at 5 years, and about 40% endure the disease for longer than 10 years.[2](https://link.springer.com/article/10.1007/s13555-024-01173-5)
Response rates follow the treatment tiers: about 40% respond to standard-dose antihistamines (a meta-analysis found 38.6%), at least 30% have an insufficient response to omalizumab, and cyclosporine improves symptoms in roughly 54% to 73%.[1](https://jamanetwork.com/journals/jama/fullarticle/2824115) • [3](https://www.jacionline.org/article/S0091-6749(22)00545-0/fulltext)
## Management
There are no curative treatments for CSU; approved therapies provide symptomatic control and do not appear to affect the natural course of the disease.[6](https://onlinelibrary.wiley.com/doi/full/10.1111/all.15603) Treatment is stepwise.
**First line.** A second-generation H1 antihistamine at a single standard dose is the universal first-line recommendation, with no evidence favoring one drug over another; about 40% of patients achieve a partial or complete response (symptom reduction greater than 50%).[5](https://pmc.ncbi.nlm.nih.gov/articles/PMC8457139/) • [10](https://pmc.ncbi.nlm.nih.gov/articles/PMC6030778/) • [1](https://jamanetwork.com/journals/jama/fullarticle/2824115) Older first-generation antihistamines were highly sedating because they enter the central nervous system; second-generation agents such as loratadine, desloratadine, cetirizine, and levocetirizine show hardly any central nervous system adverse effects.[11](https://onlinelibrary.wiley.com/doi/10.1111/ddg.12633) Some H1 antihistamines should be avoided in people with a known increase in [QT interval](https://www.edgepedia.org/qt-interval).[5](https://pmc.ncbi.nlm.nih.gov/articles/PMC8457139/)
**Second line.** If complete control is not achieved, guidelines recommend increasing the antihistamine dose up to four times the standard dose, over one week to two months.[1](https://jamanetwork.com/journals/jama/fullarticle/2824115) • [5](https://pmc.ncbi.nlm.nih.gov/articles/PMC8457139/)
**Third line.** For refractory disease with decreased quality of life, the French guideline recommends omalizumab (300 mg every 4 weeks) or ciclosporin (4–5 mg/kg per day).[5](https://pmc.ncbi.nlm.nih.gov/articles/PMC8457139/) The 2022 international guideline places omalizumab as the second-line option after antihistamine failure; at least 30% of patients respond insufficiently, especially those with IgG-mediated autoimmune urticaria.[1](https://jamanetwork.com/journals/jama/fullarticle/2824115) Cyclosporine is used off-label and improves symptoms in approximately 54% to 73% of patients, particularly those with autoimmune CSU who do not respond to omalizumab, but it carries adverse effects including kidney dysfunction and hypertension.[1](https://jamanetwork.com/journals/jama/fullarticle/2824115)
**Not recommended.** Adding H2 antihistamines or montelukast to H1 antihistamines is not recommended owing to lack of demonstrated efficacy, and systemic steroids are not recommended for CSU.[5](https://pmc.ncbi.nlm.nih.gov/articles/PMC8457139/)
A 2022 review discussed targeted therapies beyond omalizumab that were then in development, including the anti-IgE ligelizumab, the Bruton's tyrosine kinase inhibitors [fenebrutinib](https://www.edgepedia.org/fenebrutinib) and remibrutinib, and the anti–IL-4Rα antibody dupilumab.[3](https://www.jacionline.org/article/S0091-6749(22)00545-0/fulltext)
## Prognosis, control and quality of life
The World Allergy Organization defines CSU remission as the patient remaining without urticaria signs and symptoms without pharmacologic treatment.[12](https://www.jacionline.org/article/S0091-6749(24)02413-8/fulltext) Against that standard, the cumulative remission figures of 17% at 1 year and 45% at 5 years indicate that most patients require ongoing therapy for years.[1](https://jamanetwork.com/journals/jama/fullarticle/2824115) • [2](https://link.springer.com/article/10.1007/s13555-024-01173-5)
The burden extends beyond the skin. Approximately 40% of patients have a [Dermatology Life Quality Index](https://www.edgepedia.org/dermatology-life-quality-index) score above 10, corresponding to a very large or extremely large negative effect on quality of life.[1](https://jamanetwork.com/journals/jama/fullarticle/2824115) Anxiety and depression are common comorbidities, at 10% to 31% and 7% to 29% respectively.[1](https://jamanetwork.com/journals/jama/fullarticle/2824115) The economic burden is $907 to $2984 in purchasing power parity dollars annually per affected individual, mostly due to therapies.[1](https://jamanetwork.com/journals/jama/fullarticle/2824115)
## References
1. [Chronic Spontaneous Urticaria: A Review, JAMA](https://jamanetwork.com/journals/jama/fullarticle/2824115)
2. [A Practical Approach to Diagnosing and Managing Chronic Spontaneous Urticaria, Dermatology and Therapy (2024)](https://link.springer.com/article/10.1007/s13555-024-01173-5)
3. [Autoimmune chronic spontaneous urticaria, Journal of Allergy and Clinical Immunology](https://www.jacionline.org/article/S0091-6749(22)00545-0/fulltext)
4. [Prevalence, treatment and burden of chronic urticaria in the EU5, Journal of the European Academy of Dermatology and Venereology](https://www.ovid.com/journals/jeadv/fulltext/10.1111/jdv.20772~prevalence-treatment-and-burden-of-chronic-spontaneous)
5. [Guidelines for the management of chronic spontaneous urticaria: recommendations supported by the Centre of Evidence of the French Society of Dermatology](https://pmc.ncbi.nlm.nih.gov/articles/PMC8457139/)
6. [Chronic spontaneous urticaria: Focus on pathophysiology to unlock treatment advances, Allergy (2023)](https://onlinelibrary.wiley.com/doi/full/10.1111/all.15603)
7. [An Overview of Chronic Spontaneous Urticaria, Allergy, Asthma & Immunology Research (2025)](https://www.e-aair.org/pdf/10.4168/aair.2025.17.5.531)
8. [Chronic urticaria: unmet needs, emerging drugs, and new perspectives on personalised treatment, The Lancet (2024)](https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(24)00852-3/fulltext)
9. [Chronic Spontaneous Urticaria, JAMA Dermatology](https://jamanetwork.com/journals/jamadermatology/article-abstract/2840148)
10. [Management of chronic spontaneous urticaria: a worldwide perspective](https://pmc.ncbi.nlm.nih.gov/articles/PMC6030778/)
11. [Chronic spontaneous urticaria – a management pathway, Journal der Deutschen Dermatologischen Gesellschaft](https://onlinelibrary.wiley.com/doi/10.1111/ddg.12633)
12. [Chronic spontaneous urticaria remission definition and therapy stepping down: World Allergy Organization position paper (2024)](https://www.jacionline.org/article/S0091-6749(24)02413-8/fulltext)
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*Topic: Encyclopedia › Life and health › Human health and medicine › Diseases and injuries › Immune-system dysfunction and generalized hypersensitivity*
*Initially written Sep 17, 2026 · Reviewed: Oct 25, 2026 · Edited: Oct 15, 2026; Oct 25, 2026 · Last review: Oct 25, 2026*
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License: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license