Urticaria (Hives) Rash: How to Recognize It and What to Do

What urticaria looks like

• Wheals: raised, swollen areas with a pale center and red edge, from a few millimeters to several inches across. They can merge into large patches with irregular or ring-shaped borders.
• Itch: usually intense, sometimes burning or prickling.
• Moving around: each wheal fades within minutes to 24 hours, leaving normal skin, while new ones appear elsewhere. This "migrating" pattern is the hallmark.
• Blanching: pressing on a welt makes it go pale.
• Color on darker skin: wheals may look skin-colored or slightly darker rather than red.

About 4 in 10 people with urticaria also get angioedema, deeper swelling of the lips, eyelids, hands, feet or genitals that lasts up to 72 hours and is less itchy.

Urticaria vs other rashes

Common triggers of urticaria

Acute urticaria (under 6 weeks)

• Infections: viral colds and stomach bugs are the most common trigger, especially in children.
• Foods: peanuts, tree nuts, shellfish, fish, eggs, milk and wheat, usually within 2 hours of eating.
• Medicines: NSAIDs (ibuprofen, aspirin, naproxen), antibiotics such as penicillin, opioids and contrast dye.
• Insect stings and bites.
• Latex and contact with plants or animals.

Physical (inducible) triggers

• Dermatographism: wheals in lines where the skin is scratched or rubbed. The most common inducible type.
• Cold: hives after cold water, wind or ice. Swimming in cold water can be dangerous. See cold urticaria.
• Heat, exercise and sweating: tiny, very itchy wheals (cholinergic urticaria).
• Pressure: deep, painful swelling hours after tight straps or sitting.
• Sun and vibration: rare forms.

No trigger found

In many people, especially with hives lasting over 6 weeks, no external trigger is found. This is chronic spontaneous urticaria, often autoimmune, and is explained on the urticaria condition page.

How urticaria is diagnosed

Diagnosis is based on appearance and history. Taking a photo is helpful, because hives may be gone by the time of your appointment. Your doctor will ask about timing, foods, medicines, infections, physical triggers and angioedema.

• Acute hives: usually no tests, unless a food or medicine allergy is suspected, when allergy skin or blood tests help.
• Chronic hives: a few basic blood tests (blood count, CRP or ESR, sometimes thyroid antibodies).
• Inducible hives: challenge tests such as an ice cube test or stroking the skin.
• Biopsy: only when welts last over 24 hours or bruise.

Quick relief and treatment

1. Take a non-drowsy antihistamine such as cetirizine, loratadine or fexofenadine, following the label dose. Taking it daily until the hives have gone for several days works better than taking it only when itchy. Doctors sometimes recommend higher doses for persistent hives.
2. Cool the skin: cool showers, cool compresses or calamine lotion.
3. Wear loose cotton clothing and avoid tight waistbands.
4. Avoid triggers: stop NSAIDs if they seem to trigger hives (acetaminophen is usually tolerated), and avoid hot showers and alcohol during flares.
5. Short course of oral steroids: occasionally prescribed for severe acute hives.

Anyone who has had anaphylaxis should carry two epinephrine auto-injectors and see an allergist.

Frequently asked questions

What is the meaning of urticaria?

Urticaria is the medical term for hives. It describes itchy, raised welts (wheals) on the skin caused by histamine release. The name comes from the Latin word for nettle, because the rash resembles a nettle sting.

What does urticaria look like?

Urticaria looks like raised, swollen welts with pale centers and red or skin-colored edges, ranging from small dots to large patches. Each welt disappears within 24 hours while new ones appear elsewhere. Pressing on a welt makes it turn pale.

What is the most common cause of urticaria?

In acute urticaria, viral infections are the most common trigger, especially in children, followed by foods, medicines such as NSAIDs and antibiotics, and insect stings. In chronic urticaria, most cases have no external trigger and are thought to be autoimmune.

How long does urticaria last?

Acute urticaria usually clears within days to a few weeks. If hives come and go for 6 weeks or more, it is called chronic urticaria. Chronic urticaria often lasts 1 to 5 years but eventually goes away in most people.

Is urticaria contagious?

No. Urticaria is not contagious and cannot be passed on by touch. However, a viral infection that triggered it may be contagious.