From the Guidelines
A wheal is a raised, itchy, reddened area of skin that appears as a reaction to various stimuli, typically developing rapidly and resolving within 24 hours, as noted in the guidelines for evaluation and management of urticaria in adults and children 1.
Definition and Characteristics
A wheal is characterized by localized swelling caused by fluid leaking from blood vessels into surrounding tissues, resembling a mosquito bite or hive. Wheals can vary in size from a few millimeters to several centimeters and may appear individually or in clusters. They commonly result from allergic reactions, insect bites, physical stimuli like pressure or cold, or certain medications.
Causes and Triggers
The formation of wheals involves the release of histamine and other inflammatory chemicals in the skin, which causes blood vessels to dilate and become more permeable, as discussed in the context of urticaria management 1. Identifying and avoiding triggers is important for preventing recurrence. According to the guidelines, over 40% of hospitalized patients with urticaria show a good response to antihistamines, which are the mainstay of therapy 1.
Treatment and Management
Treatment typically involves antihistamines like diphenhydramine (Benadryl) or cetirizine (Zyrtec) to reduce itching and inflammation. For severe or persistent cases, corticosteroids or other anti-inflammatory medications may be necessary. Advice on general measures and information can be helpful for most patients with urticaria, especially if an avoidable physical or dietary trigger can be identified 1.
Key Considerations
- Wheals are temporary and resolve within 24 hours, though new ones may continue to form.
- Identifying and avoiding triggers is crucial for preventing recurrence.
- Antihistamines are the mainstay of therapy for urticaria, with over 40% of hospitalized patients showing a good response 1.
From the Research
Definition of Wheal
- A wheal is a raised, itchy area of skin that is usually the result of an allergic reaction, but the provided studies do not directly define or discuss wheal.
- The studies focus on anaphylaxis, a severe, life-threatening allergic reaction, and its treatment, particularly the use of epinephrine 2, 3, 4, 5, 6.
Anaphylaxis Treatment
- Epinephrine is the first-line treatment for anaphylaxis, and its early administration is critical to prevent fatal outcomes 2, 3, 4, 5, 6.
- Antihistamines and corticosteroids may be used as secondary treatments, but they should not delay the administration of epinephrine 3, 4, 6.
- The provided studies do not mention wheal as a specific symptom or condition, but they discuss the importance of prompt treatment for anaphylaxis, which can cause various skin symptoms, including hives and itching 2, 3, 4, 5, 6.