From the Guidelines
Urticaria is caused by the release of histamine and other inflammatory mediators from mast cells in the skin, triggered by various factors including allergic reactions, physical stimuli, infections, and autoimmune conditions. The most common triggers include allergic reactions to foods, medications, insect stings or bites, and latex. Physical factors can also induce urticaria, including pressure, cold, heat, sunlight, exercise, and vibration. Infections, particularly viral respiratory infections, streptococcal infections, and Helicobacter pylori, may trigger acute urticaria 1.
Some key points to consider in the causes of urticaria include:
- Allergic reactions to foods, such as nuts, shellfish, eggs, and milk
- Medications, such as antibiotics like penicillin, NSAIDs, and aspirin
- Insect stings or bites
- Latex
- Physical factors, including pressure, cold, heat, sunlight, exercise, and vibration
- Infections, particularly viral respiratory infections, streptococcal infections, and Helicobacter pylori
- Autoimmune conditions, such as thyroid disease or lupus, in chronic cases lasting more than six weeks
It's also important to note that in about 40% of chronic urticaria cases, no specific cause is identified, which is termed idiopathic urticaria 1. Understanding the specific trigger is important for effective management, as avoidance of known triggers is the first step in preventing recurrent episodes. The clinical classification of urticarias can be helpful in identifying the underlying cause, including ordinary urticaria, physical urticarias, and other types such as contact urticaria and urticarial vasculitis 1.
In terms of management, antihistamines are the mainstay of therapy, and guidance for treatment is presented based on the strength of evidence available 1. The choice of antihistamine and treatment approach should be individualized based on the patient's specific needs and circumstances.
From the Research
Causes of Urticaria
- Urticaria, also known as hives, is a common disease characterized by erythematous, edematous, itchy, and transient plaques that involve skin and mucous membranes 2
- Many factors are accused of etiology, including:
- Infections
- Medicines
- Food
- Psychogenic factors
- Respiratory allergens
- Sometimes, the cause of urticaria is idiopathic, meaning that it is unknown 2
- Urticaria can result from many different stimuli, and numerous factors, both immunologic and nonimmunologic, are involved in its pathogenesis 3
- Immunologic mechanisms, such as the type I hypersensitivity state mediated by IgE, and the activation of the complement cascade, which produces anaphylatoxins that can release histamine, can contribute to the development of urticaria 3
Types of Urticaria
- Acute spontaneous urticaria
- Chronic spontaneous urticaria
- Chronic inducible urticaria
- Episodic chronic urticaria 2
- Physical urticarias, such as cold, cholinergic, and pressure urticaria 4
Pathogenesis of Urticaria
- Histamine is the best-documented chemical mediator of urticaria, and histamine-antagonists are the mainstay of therapy 5
- Other mediators, such as kinins, serotonin, slow-reacting substance of anaphylaxis, prostaglandins, acetylcholine, fibrin degradation products, and anaphylatoxins, can also contribute to the development of urticarial lesions 3
- The release of these mediators from mast cells and basophils can increase vascular permeability and produce wheals 3