Understanding Chronic Urticaria
A clear, patient-friendly guide to what chronic urticaria is, how it shows up, how it is diagnosed and what it means for everyday life.
Educational information only. This information is for educational purposes and does not replace professional medical advice. Always speak to a qualified doctor about your symptoms and treatment.
What is Chronic Urticaria?
Urticaria is the medical name for hives. When hives, deeper swelling (angioedema), or both keep returning for more than 6 weeks, it is called chronic urticaria (CU).
What is CSU?
Chronic Spontaneous Urticaria is the most common type. Symptoms appear on their own, without a specific external trigger. In many people, the immune system plays a role.
Acute vs Chronic Urticaria
| Acute urticaria | Chronic urticaria | |
|---|---|---|
| Duration | Less than 6 weeks | 6 weeks or longer |
| Common causes | Often an infection, medicine or food | Usually no external cause found (CSU), or a physical trigger (CIndU) |
| How common | Very common — up to 1 in 5 people in their lifetime | Less common — around 0.5–1% of people |
| Outlook | Usually settles within days to weeks | Can last months to years; often improves over time |
Chronic Spontaneous Urticaria
No specific trigger
Chronic Inducible Urticaria
Triggered by cold, pressure, heat, sun, scratching or exercise
Symptoms: hives and angioedema
Hives (wheals)
Superficial · on the skin surface
- Raised, red or skin-coloured, very itchy welts
- Each wheal usually fades within 24 hours
- Can appear anywhere and change shape or location
- Leave no mark or bruise after fading
Angioedema
Deeper · beneath the skin
- Swelling of lips, eyelids, hands, feet or genitals
- Often painful or burning rather than itchy
- Can last up to 72 hours
- Affects around 4 in 10 people with CSU
Possible triggers that can make symptoms worse
In CSU these don't cause the condition, but they may trigger flares in some people.
How CSU is diagnosed
Medical history
Your doctor asks when symptoms started, how long wheals last, possible triggers, medicines and family history.
Physical examination
Photos of your hives on your phone are very helpful, as symptoms may not be visible during the visit.
Limited, targeted tests
Usually a few basic blood tests. Extensive allergy testing is rarely needed for CSU.
Measuring activity & control
Simple tools like the UAS7 score and Urticaria Control Test (UCT) track how you are doing over time. Try our UAS7 tracker.
Disease duration
CSU is unpredictable, but it is usually not lifelong.
Many people see symptoms ease or disappear within a few years. Treatment helps control symptoms in the meantime.
Impact on quality of life
What people with CSU commonly report:
- Disturbed sleep from night-time itch
- Reduced work or study performance
- Anxiety or low mood
- Avoiding social activities
Tell your doctor about these effects — they are part of how CSU is assessed.
Common misconceptions
"It's just an allergy."
FactIn most people with CSU, no allergy is found. It is linked to the immune system and mast cells.
"It's contagious."
FactCSU cannot be caught from or passed to anyone.
"It's caused by stress or bad diet."
FactStress may worsen flares, but it does not cause CSU. Restrictive diets rarely help.
Call emergency services (112) immediately if you have:
- Swelling of the tongue, throat or mouth
- Difficulty breathing, wheezing or swallowing
- Dizziness, fainting or a sudden drop in wellbeing
Book a doctor's appointment if:
- Hives or swelling keep coming back for more than 6 weeks
- Symptoms affect your sleep, work or daily life
- Your current treatment is not controlling symptoms
- You have new symptoms such as fever or joint pain
Make the most of your next doctor visit
Our free Doctor Discussion Guide helps you explain what CSU is doing to your life, track your symptoms for a week and ask the right questions. Print it or keep it on your phone.
- Appointment checklist — what to bring
- Questions to ask your doctor
- 7-day symptom diary (UAS7) with scoring
PDF · 4 pages · Medically reviewed · No sign-up needed