The medical term for hives is urticaria, a skin reaction made of raised, itchy, pale red or skin colored bumps that come and go. Each individual bump is called a wheal, and a person may have a few or hundreds.
Urticaria is said ur-tih-KAIR-ee-uh and comes from the Latin word for nettle, the plant whose sting leaves similar welts. It often shows up in allergy notes and medication reaction entries, and it is grouped with swelling deeper in the skin called angioedema. Here is how the terms fit together, what acute and chronic mean, and when hives become an emergency.
At a glance
Medical term
UrticariaSingle bump
Wheal, also spelled wealLatin origin
Urtica, nettleAdjective
Urticarial, as in urticarial rashDeeper swelling
Angioedema, often of lips, eyelids or tongueSpecialty
Allergy and immunology, dermatology
Wheals, flares and the medical term for hives
A wheal is a raised, swollen patch on the top layer of skin, often pale in the center with a red rim around it called a flare. Wheals usually itch, can merge into large patches, and change shape. A key feature is that each one typically fades within 24 hours, even while new ones appear elsewhere. That moving pattern helps clinicians tell urticaria from other rashes.
The welts form when certain immune cells in the skin release histamine and related chemicals. Histamine makes small vessels leak fluid into the skin, causing swelling and itch. That is why antihistamines are a common treatment, though which medicine fits is decided case by case.
Acute versus chronic urticaria
| Term | Time frame | Typical causes |
|---|---|---|
| Acute urticaria | Less than six weeks | Infections, foods, medicines, insect stings; often no cause found |
| Chronic urticaria | Six weeks or longer, with hives on most days | Usually no outside trigger; the immune system itself is often involved |
| Inducible urticaria | Any duration | Physical triggers such as pressure, cold, heat, sun or scratching |
One form of inducible urticaria is dermatographism, where firmly stroking the skin raises a welt in the shape of the line. Chronic urticaria without a clear trigger is often called chronic spontaneous urticaria.
Reading hives in an allergy entry
Medication reaction note: "Diffuse urticaria after PCN dose; no angioedema, airway patent." This means widespread hives appeared after a dose of penicillin (PCN). There was no deeper swelling, and the breathing passage was open.
Notes like this matter because they shape the allergy list. A person with a recorded hive reaction will no longer show NKDA, no known drug allergies, and the reaction type is written next to the drug name. Allergy specialists can later test whether the allergy is real, since many people labeled allergic to penicillin turn out to tolerate it.
Angioedema and anaphylaxis
Angioedema is swelling in deeper layers of skin and tissue. It often affects the lips, eyelids, tongue, hands or feet, tends to feel tight or painful more than itchy, and can last longer than hives. It can occur with urticaria or alone.
Anaphylaxis is a severe, body wide allergic reaction. Hives can be one part of it, along with throat tightness, trouble breathing, wheezing, vomiting, dizziness or fainting. Anaphylaxis is an emergency: people who carry epinephrine are taught to use it and call 911. Hives alone, without these signs, are usually not dangerous, but swelling of the tongue or throat always needs urgent care.
Frequently asked questions
What do doctors call hives?
Doctors call hives urticaria. Each raised bump is a wheal.
How do you pronounce urticaria?
Say ur-tih-KAIR-ee-uh; the KAIR part is loudest. The adjective is urticarial.
What is the difference between hives and angioedema?
Hives are raised itchy welts in the top layers of skin, while angioedema is swelling deeper down, often around the eyes, lips or tongue. They can happen together.
When are hives considered chronic?
Hives are called chronic when they appear on most days for six weeks or longer. Shorter bouts are acute urticaria.
Are hives always an allergy?
No. Infections, physical triggers such as cold or pressure, and immune processes can all cause hives, and often no cause is found.