Wheal
What is it?
A wheal (also called a hive or welt) is a raised, swollen area of skin that appears suddenly and usually disappears within 24 hours. It's caused by fluid leaking from blood vessels into the skin, creating temporary swelling. Think of it like a mosquito bite - that raised, itchy bump is a small wheal. Wheals are the main feature of hives (urticaria) and result from allergic reactions, physical triggers, or sometimes occur without a clear cause.
What does it look like?
Wheals have distinctive features:
- Raised, swollen bumps that appear suddenly
- Color: Pink, red, or skin-colored with pale centers
- Size: From tiny dots to large patches several inches across
- Shape: Round, oval, or irregular; may form rings or bizarre patterns
- Surface: Smooth and slightly dome-shaped
- Blanching: Turn white when pressed (blanching)
- Duration: Individual wheals last less than 24 hours
- Movement: New ones appear as old ones fade
Where does it appear?
Wheals can appear anywhere:
- Trunk: Common site for widespread hives
- Arms and legs: Often from insect bites or reactions
- Face and lips: May swell significantly (angioedema)
- Hands and feet: Pressure-induced wheals
- Areas of tight clothing: Pressure urticaria
- Scratch marks: Linear wheals from dermographism
- Anywhere: Can appear on any part of the body
Associated features
Wheals are typically accompanied by:
- Intense itching (main symptom)
- Burning or stinging sensation
- Swelling of deeper tissues (angioedema) - lips, eyelids, tongue
- New wheals appearing as others fade
- Clear triggers (foods, medications, stress, exercise)
- Worse at night or with heat
- No lasting marks after wheals disappear
- May be part of severe allergic reaction
When to see a doctor
Seek immediate emergency care for:
- Difficulty breathing or swallowing
- Swelling of tongue or throat
- Rapid pulse or dizziness
- Wheals with severe nausea or vomiting
See a doctor soon for:
- Wheals lasting more than 24 hours in same spot
- Daily hives for more than 6 weeks
- Wheals that are painful rather than itchy
- Wheals with fever or joint pain
- Hives not responding to antihistamines
- Recurring episodes affecting quality of life
References
Primary Sources
Description of Skin Lesions - Merck Manual Professional Edition (2024)
- URL: https://www.merckmanuals.com/professional/dermatologic-disorders/approach-to-the-dermatologic-patient/description-of-skin-lesions
- Key findings: Wheals as elevated lesions caused by localized edema, pruritic and erythematous
Terminology in Dermatology - DermNet NZ (2024)
- URL: https://dermnetnz.org/topics/terminology
- Key findings: Wheal characteristics and transient nature <24 hours
Urticaria Guidelines - American Academy of Allergy, Asthma & Immunology (2024)
- Key findings: Clinical features and classification of wheals in urticaria
Additional Sources
- Primary Skin Lesions - UTMB Dermatology - URL: https://www.utmb.edu/pedi_ed/CoreV2/Dermatology/page_07.htm - Accessed: 2025-09-30
- Stanford Medicine 25 - URL: https://stanfordmedicine25.stanford.edu/the25/dermatology.html - Accessed: 2025-09-30
Research Notes
- URL: https://pubmed.ncbi.nlm.nih.gov/ - Topic researched: Urticaria, wheal pathophysiology, angioedema
- URL: https://dermnetnz.org/ - Topic researched: Wheal characteristics, dermographism, physical urticarias