Urticaria
Also known as: Hives
Raised, itchy welts that appear suddenly. Usually from allergic reactions, stress, or infections. Most cases resolve within 24 hours.
What to look for
Side-by-side comparison
Normal skin
No raised welts
Urticaria (hives)
Raised itchy welts, come and go
Urticaria (hives) presents as raised, itchy, well-defined welts (wheals) that can appear anywhere on the body. Individual wheals are characteristically transient - each one typically lasts less than 24 hours, though new ones may continue to appear.
Acute urticaria (lasting less than 6 weeks) is most often triggered by allergic reactions (foods, medications, insect stings), viral infections, or stress. Chronic urticaria (lasting more than 6 weeks) is often idiopathic - no identifiable trigger - and may have an autoimmune component.
The mechanism involves mast cell degranulation releasing histamine, which causes blood vessel dilation and fluid leakage into the skin. Angioedema (deeper swelling, often of the lips, eyelids, or hands) can accompany hives.
Treatment centers on antihistamines. Second-generation non-sedating antihistamines (cetirizine, loratadine, fexofenadine) are first-line. For chronic urticaria not responding to antihistamines, omalizumab (anti-IgE biologic) is effective. Anaphylaxis with hives requires emergency epinephrine.
Quick self-check
Does this look like urticaria? Answer 2 questions.
Are there raised, itchy welts that come and go within hours?
Did they appear suddenly after food, medication, or stress?
Risk factors
- Allergies (food, medications, insect stings)
- Viral infections (common trigger in children)
- Stress
- Autoimmune conditions
- Physical triggers (cold, pressure, exercise, sun)
When to see a dermatologist
- ⚠Hives accompanied by difficulty breathing or throat swelling (emergency - call 911)
- ⚠Hives lasting more than 6 weeks (chronic urticaria needs workup)
- ⚠Hives not responding to over-the-counter antihistamines
- ⚠Recurrent episodes without identifiable trigger
Often confused with
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Full ABCDE check →Frequently asked questions
When are hives an emergency?
Seek immediate emergency care if hives are accompanied by difficulty breathing, throat tightness or swelling, tongue swelling, dizziness, or rapid heartbeat. This may indicate anaphylaxis, which requires epinephrine.
Why can my doctor not find the cause of my chronic hives?
In about 50% of chronic urticaria cases, no specific trigger can be identified (chronic idiopathic urticaria). Many of these have an autoimmune basis. The good news: effective treatments exist regardless of whether a cause is found.