Following an overview of the classification of urticaria, the overall framework may now be clearer.
Here, we further examine the clinical characteristics of each subtype.
Idiopathic Urticaria
Idiopathic urticaria occurs without an identifiable external trigger and tends to appear almost daily, often worsening from evening to night. Wheals show variable morphology, including round, oval, and geographic patterns.
Acute urticaria is frequently associated with infections, particularly in children, whereas chronic urticaria is often related to fatigue and psychological stress. In adult women, symptoms may fluctuate in association with the menstrual cycle.
Among systemic diseases, systemic lupus erythematosus (SLE) is relatively well known in association with urticaria, with urticaria-like lesions reported in approximately 7% of patients. Urticarial vasculitis may, in some cases, represent an early manifestation.
Associations with internal malignancies and Helicobacter pylori infection have been suggested, although causal mechanisms remain unclear. Chronic urticaria has also been reported in association with hepatitis B and C, as well as thyroid disorders, particularly in women.
Autoantibodies such as anti-IgE and anti-FcεRI antibodies are detected in 30–60% of chronic cases; however, their direct pathogenic role remains uncertain.
Recent studies have demonstrated abnormalities in coagulation markers, including D-dimer and fibrin degradation products (FDP). These findings suggest a possible contribution of coagulation processes to disease activity, although they are better regarded as background factors rather than primary causes.
Antihistamines remain the mainstay of treatment. Systemic corticosteroids may be effective but should be used cautiously.
Inducible Urticaria
Inducible urticaria refers to forms in which specific stimuli reproducibly trigger wheal formation.
Allergic Urticaria
This type is induced by foods, drugs, or latex and is mediated by IgE-dependent type I hypersensitivity reactions. It represents a typical allergic response and may be associated with anaphylaxis.
Oral allergy syndrome is classified into three groups:
Gastrointestinal sensitization (common in infants)
Cross-reactivity with environmental antigens (e.g., pollen–food, latex–fruit syndromes)
Percutaneous or transmucosal sensitization
Food-Dependent Exercise-Induced Anaphylaxis
This condition occurs when food ingestion is combined with exercise or NSAIDs. Increased intestinal absorption of allergens is thought to play a role. Wheat and shellfish are well-known triggers.
Non-Allergic Urticaria
Some food-related urticaria is non-allergic and results from histamine or histamine-like substances. These reactions (pseudoallergens) are not detected by standard allergy testing.
Intolerance
Non-immunological reactions, such as aspirin intolerance or sensitivity to food additives (e.g., tartrazine, nitrites, monosodium glutamate), may induce urticaria. Reactions to contrast media are also included in this category.
Cholinergic Urticaria
This subtype is characterized by small wheals triggered by increased body temperature, such as during exercise, bathing, or emotional stress. Patients often report a stinging sensation rather than itching.
Physical Urticaria
Physical urticaria accounts for approximately 10% of cases and is induced by stimuli such as pressure, cold, or sunlight. Diagnosis is often facilitated by provocation testing.
General Considerations
In many cases, urticaria arises without a single identifiable cause. Non-specific factors such as stress, sleep deprivation, bathing, and alcohol consumption frequently contribute.
Extensive laboratory testing rarely alters clinical management. Reports have shown that, even when abnormalities are detected, they often do not lead to changes in treatment.
The “dial lock theory” provides a useful conceptual model:
urticaria develops when multiple contributing factors accumulate and exceed a certain threshold. Conversely, reduction of these factors below the threshold may result in symptom resolution.
This perspective is practical in daily clinical care and may help avoid excessive focus on identifying a single causative factor.
References
Hide M, et al.
Guidelines for the Diagnosis and Treatment of Urticaria.
The Japanese Journal of Dermatology. 2011;121(7):1339–1388.
Furue M, Hide M (eds).
Urticaria and Angioedema: Perfect Master.
Nakayama Shoten; 2013.
English version prepared with AI assistance
(Originally published in Japanese)
Japanese version:
https;//hifuka-otibohiroi.net/post2/