Urticaria (Hives): Acute and Chronic Types and Treatment

How urticaria happens

Mast cells in the skin hold granules packed with histamine. When they are activated, they release histamine and other chemicals that make small blood vessels leak fluid into the skin, forming itchy wheals. In deeper tissue, the same process produces angioedema.

In acute urticaria, the trigger is usually an allergic reaction (IgE antibodies to a food, sting or drug) or a non-allergic activation by infections or medicines such as NSAIDs. Allergic hives can occasionally be the first sign of anaphylaxis.

In chronic spontaneous urticaria, the immune system itself drives mast cell activation. In many people, autoantibodies target the IgE receptor on mast cells or IgE itself. This is why chronic urticaria is linked with autoimmune thyroid disease and is not usually caused by allergies.

Types of urticaria

Chronic inducible urticaria subtypes

• Symptomatic dermatographism: wheals where skin is rubbed or scratched.
• Cold urticaria: after contact with cold air, water or objects. Cold water swimming can cause severe reactions.
• Cholinergic urticaria: tiny itchy bumps with sweating, exercise, hot showers or emotional stress.
• Delayed pressure urticaria: deep painful swelling 4 to 8 hours after pressure.
• Solar, heat contact, vibratory and aquagenic urticaria: rare.

Symptoms

• Itchy, raised wheals (hives) that last minutes to 24 hours each and move around
• Angioedema: swelling of lips, eyelids, hands, feet or genitals lasting up to 3 days
• Symptoms often worse in the evening or at night
• Flares with stress, infections, NSAIDs, alcohol, heat and tight clothing

Chronic urticaria significantly disturbs sleep, work and mood. Doctors often track it with the Urticaria Activity Score (UAS7), a daily diary of wheals and itch.

Causes and aggravating factors

Acute urticaria

• viral and bacterial infections
• foods (peanuts, nuts, shellfish, eggs, milk)
• medicines (penicillins, NSAIDs, opioids, contrast)
• insect stings, latex

Chronic urticaria

• No external cause in most cases (autoimmune mechanism)
• Aggravating factors: NSAIDs, aspirin, alcohol, heat, stress, infections, tight clothing
• Associated conditions: autoimmune thyroid disease is the most common association

Food allergy is a very rare cause of chronic urticaria. Extensive allergy testing and restrictive diets are generally not helpful.

Diagnosis

• Acute urticaria: clinical diagnosis. Allergy testing only if a specific food, sting or drug is suspected.
• Chronic spontaneous urticaria: a limited set of tests, usually a blood count, CRP or ESR, and often total IgE and thyroid antibodies (anti-TPO). Broad screening is not recommended.
• Inducible urticaria: provocation tests such as an ice cube test, a dermographometer or exercise testing.
• Biopsy: if wheals last more than 24 hours, burn or bruise, to look for urticarial vasculitis.
• Angioedema without hives: tests for ACE inhibitor-related or hereditary angioedema (complement C4, C1 inhibitor), which do not respond to antihistamines.

Treatment: the step-by-step approach

International guidelines recommend:

1. Step 1: Daily second-generation antihistamine (cetirizine, levocetirizine, loratadine, desloratadine, fexofenadine, bilastine) at the standard dose, taken every day rather than as needed.
2. Step 2: Increase the antihistamine up to 4 times the standard dose under medical supervision if hives are not controlled after 2 to 4 weeks. This is off-label but well established and generally safe.
3. Step 3: Add omalizumab, an injection every 4 weeks that targets IgE. It controls symptoms in most people who do not respond to antihistamines. Other biologic and targeted medicines have been approved more recently for antihistamine-resistant chronic spontaneous urticaria, and availability varies.
4. Step 4: Cyclosporine, an immune-suppressing medicine, for those who do not respond to omalizumab, with blood pressure and kidney monitoring.

Short courses of oral steroids (up to about 10 days) may be used for severe flares, but long-term steroids are avoided because of side effects.

Older sedating antihistamines are not recommended for long-term use because they impair sleep quality, concentration and driving.

Practical self-care

• Avoid NSAIDs and aspirin if they worsen hives; acetaminophen (paracetamol) is usually tolerated.
• Limit alcohol and very hot showers during flares.
• Wear loose clothing.
• Manage stress, which can worsen flares.
• Keep a symptom diary or photos to share with your doctor.

Pregnancy and children

Loratadine and cetirizine are the antihistamines most commonly used in pregnancy, but discuss treatment with your doctor. In children, acute urticaria is very common, usually after viral infections, and most chronic urticaria in children also resolves.

Outlook

Acute urticaria usually settles within days to weeks. Chronic spontaneous urticaria resolves within 1 year in about half of people and within 5 years in most, though some have it longer. Symptoms may return after remission. Urticaria does not damage internal organs, but effective treatment greatly improves quality of life.

Frequently asked questions

What is the difference between acute and chronic urticaria?

Acute urticaria lasts less than 6 weeks and often has a clear trigger such as an infection, food or medicine. Chronic urticaria lasts 6 weeks or more and usually has no external trigger. It is thought to be autoimmune in many cases and is managed with daily treatment.

What causes chronic urticaria?

Most chronic urticaria is spontaneous, meaning there is no outside trigger. In many people the immune system produces antibodies that activate skin mast cells. Physical factors cause the inducible forms. Allergies to food are rarely the cause.

Can chronic urticaria be cured?

There is no cure, but treatment controls it in most people, and chronic urticaria eventually goes away on its own in the majority, often within 1 to 5 years. Daily antihistamines, sometimes at higher doses, and omalizumab are very effective.

Is it safe to take high-dose antihistamines?

Under medical supervision, taking up to 4 times the standard dose of second-generation antihistamines is recommended by international guidelines and is generally safe and well tolerated. Drowsiness can increase with some types. Do not increase doses without speaking to your doctor.

Can stress cause urticaria?

Stress does not cause urticaria on its own, but it commonly makes chronic urticaria flare. Managing stress, getting enough sleep and controlling symptoms with daily antihistamines help break the cycle of itch, poor sleep and stress.