Hives (urticaria) and angioedema: causes, treatment, when to see a GP

What hives and angioedema are

Hives — known medically as urticaria — are raised, itchy welts that come up on the skin and usually fade within 24 hours, often without leaving any mark. Each individual welt is short-lived even though the overall episode may keep producing new welts day after day. On lighter skin tones they look red or pink; on darker skin they may appear as blotchy patches that you can feel as well as see.

Angioedema is deeper swelling in the tissue under the skin — typically of the lips, tongue, eyelids, hands, feet or genitals, and sometimes the throat. It tends to feel tight or burning rather than itchy, takes longer to settle (often 24 to 72 hours), and is the form to take seriously when the lips, tongue or throat are involved.

Hives and angioedema often occur together — about half of people with chronic hives also get some angioedema — but angioedema can also occur on its own, and the pattern of angioedema without hives points to specific causes that need investigating (ASCIA).

A useful framing is the time course:

• Acute urticaria lasts less than six weeks. About 15 to 20% of Australians will have at least one episode in their lifetime.
• Chronic urticaria lasts six weeks or more, with welts coming and going on most days. Chronic spontaneous urticaria affects around 1% of people at some point, is roughly twice as common in women, and most often runs for two to five years before settling.

What causes hives

Acute hives

For a one-off or short-lived episode, the most common causes are:

• Viral infections — particularly common in children and after a recent cold or other viral illness.
• Foods — shellfish, nuts, eggs, dairy, wheat and sometimes fruits or food additives.
• Medications — antibiotics (especially penicillins), anti-inflammatories such as ibuprofen and aspirin, opioid painkillers, contrast dye used in scans.
• Insect stings — especially bees, wasps and jack jumper ants in Australia.
• Physical triggers — cold, heat, pressure, sunlight, exercise, sweating, water.

Often the trigger is obvious; sometimes no clear cause is identified and the hives simply settle on their own within days to a few weeks.

Chronic spontaneous urticaria (CSU)

This is the most common form of long-lasting hives and is one of the most misunderstood conditions in general practice. It is not an allergy in the usual sense — there is no specific food or environmental allergen to find and avoid. In about 40% of cases, the immune system produces autoantibodies that activate the histamine-releasing cells in the skin (mast cells), which is why allergy testing rarely identifies a cause and elimination diets are usually disappointing.

People with chronic hives often have other autoimmune conditions, especially autoimmune thyroid disease, so your GP may check thyroid function and thyroid antibodies as part of the workup (ASCIA).

Common aggravators — things that worsen existing hives without being the underlying cause — include:

• Anti-inflammatory medications (NSAIDs such as ibuprofen, aspirin, naproxen) — these flare hives in roughly 30% of people with chronic urticaria.
• Alcohol.
• Heat and hot showers.
• Stress and poor sleep.
• Tight clothing pressure points.

Chronic inducible urticaria

Less commonly, hives are reliably triggered by a specific physical stimulus: cold (including cold drinks and cold-water swimming), heat, pressure, exercise, water contact, sunlight, or simply stroking the skin (dermographism). These respond to antihistamines and trigger avoidance.

Angioedema without hives — a different category

When the deep swelling happens without any itchy hives, the cause is often different from typical histamine-driven urticaria:

• ACE inhibitor blood pressure medications (such as perindopril, ramipril, enalapril) can cause angioedema, sometimes years after starting them. This is a recognised side effect — your GP will usually switch you to a different blood pressure tablet.
• Hereditary angioedema (HAE) — a rare inherited condition that runs in families. People typically have recurrent attacks of swelling, sometimes with severe abdominal pain, that don’t respond to antihistamines, adrenaline or steroids. Diagnostic blood tests check complement levels (C4) and a protein called C1 inhibitor.
• Acquired C1 inhibitor deficiency — uncommon, occurring in older adults, sometimes linked to underlying blood conditions.

If you have recurrent swelling without hives, your GP will refer you to a clinical immunologist for specific blood tests, because the treatment is different from ordinary urticaria.

How hives are diagnosed

Diagnosis is mostly clinical — your GP will ask about the timeline, triggers, what the welts look like, how long individual welts last, family history of allergy or unusual swelling, current medications (particularly ACE inhibitor blood pressure tablets, NSAIDs and antibiotics), and any associated breathing, gut or joint symptoms.

For acute hives, no testing is usually needed beyond the consultation. The condition is recognisable, the trigger is often obvious, and the welts settle.

For chronic hives (more than six weeks), targeted blood tests are recommended by eTG and the EAACI / WAO 2022 international guideline:

• Full blood count and inflammatory markers (CRP, ESR).
• Thyroid function and thyroid antibodies (autoimmune thyroid disease is more common in chronic urticaria).
• Liver and kidney function.
• Coeliac screening if there are gut or anaemia features.

Allergy testing (skin-prick or specific IgE blood tests) is not routinely useful for chronic spontaneous urticaria and is reserved for cases where a specific food or drug is plausibly suspected. Time, money and stress are saved by skipping broad allergy panels.

For angioedema without hives, your GP will arrange specific complement testing (C4, C1 inhibitor level and function) and refer to a clinical immunologist if hereditary angioedema is a possibility.

A skin biopsy is occasionally needed if individual welts last more than 24 hours, leave bruising, or feel burning rather than itchy — a pattern that can indicate urticarial vasculitis, which is investigated differently.

How hives are treated

Step 1 — Non-drowsy antihistamines

Modern second-generation antihistamines are the cornerstone of treatment. They block histamine without causing the sedation, fall risk and memory problems seen with older sedating antihistamines. Examples available in Australia include:

• Cetirizine
• Loratadine
• Fexofenadine
• Desloratadine
• Bilastine
• Levocetirizine
• Rupatadine

Most are available over the counter. Taking them daily during an active episode — rather than only when welts appear — is more effective.

Step 2 — Increasing the dose

If standard once-daily dosing is not controlling symptoms, current Australian and international guidelines (per eTG and the EAACI / WAO 2022 guideline) support increasing the dose up to four times the standard amount under your GP’s supervision. This is well-tolerated and guideline-supported, even though it’s technically off-label. Many people who think antihistamines aren’t working simply haven’t been on a high-enough dose.

Step 3 — Omalizumab for severe chronic hives

For chronic spontaneous urticaria that doesn’t respond after six weeks of high-dose antihistamines, omalizumab (Xolair) has changed treatment. It’s an injection given under the skin every four weeks that blocks the antibody (IgE) involved in mast cell activation. In Australia it is PBS-subsidised under Authority Required for severe chronic spontaneous urticaria refractory to high-dose antihistamines, initiated by a specialist (immunologist, allergist or dermatologist) (PBS). Many people who had failed every previous treatment respond well, often within the first one to two injections.

Step 4 — Specialist immunosuppression

A very small number of people with severe omalizumab-refractory disease are managed by specialists with ciclosporin, an immunosuppressant requiring close blood-pressure and kidney monitoring.

What to avoid

• Long-term oral steroids — effective in the short term, but the side effect profile (weight gain, bone thinning, blood-pressure rise, mood change, infection risk) and the rebound flare when stopped make them unsuitable for ongoing use. A short course of prednisolone can be reasonable for a severe acute flare but is not a long-term answer.
• Older sedating antihistamines (such as promethazine) for daily use — they cause drowsiness, dry mouth and falls, and offer no advantage over non-drowsy options.
• Montelukast as a routine add-on — it has only modest benefit in chronic urticaria and carries a TGA Boxed Warning for neuropsychiatric side effects including agitation, depression, sleep disturbance and suicidal thoughts. If it is prescribed, mental health changes should be monitored.

Treatment of hereditary angioedema

Hereditary angioedema is managed by clinical immunologists with specific medications that target the bradykinin pathway — including C1 inhibitor concentrate, icatibant and lanadelumab — available through the PBS Section 100 (Highly Specialised Drugs) program. Ordinary antihistamines and adrenaline don’t work for HAE attacks, which is why getting the diagnosis right matters.

When to see your GP

Book a regular GP appointment if you have:

• Hives lasting more than a few days that aren’t settling.
• Recurring episodes of hives with no obvious trigger.
• Hives that have been coming and going for more than six weeks.
• Repeated angioedema without itchy hives — especially if you take an ACE inhibitor blood pressure tablet.
• Family history of unusual swelling attacks (possible hereditary angioedema).
• A reaction to a medication, food, or insect sting that involved breathing, throat tightness or feeling faint — even if it has now resolved.
• Hives that are significantly affecting sleep, mood, work or daily life.

Chronic urticaria carries a real psychological burden that is sometimes minimised — persistent itch and unpredictable flares affect sleep, concentration and mood, and a Mental Health Care Plan through your GP can provide subsidised psychology support where helpful.

Red flags — call 000 immediately

Call 000 for an ambulance if you have any of the following:

• Swelling of the lips, tongue or throat with trouble breathing, swallowing or speaking.
• A tight feeling in the throat, noisy breathing, wheeze, or a hoarse voice.
• Sudden widespread hives together with feeling faint, dizzy, a racing heart, vomiting, or severe abdominal pain — this may be anaphylaxis.
• Loss of consciousness or collapse.

If you have ever been prescribed an adrenaline auto-injector (EpiPen or Anapen) for previous anaphylaxis, use it immediately into the outer thigh at the first sign of throat or breathing involvement, lie flat (or sit up only if breathing is too difficult lying down), and then call 000. Adrenaline given early is the most important treatment in anaphylaxis — antihistamines and steroids are not a substitute (ASCIA Anaphylaxis Guidelines).

For severe acute abdominal pain in someone with known hereditary angioedema, present to the emergency department — HAE attacks can affect the bowel as well as the skin and need specific treatment.

What this article is and is not

This is general health information drawn from current Australian clinical guidance — including ASCIA, Therapeutic Guidelines (eTG), the Australian Medicines Handbook, the TGA, and the EAACI / WAO 2022 international urticaria guideline. It is not personal medical advice and does not create a doctor–patient relationship. Treatment decisions should be made with your own GP, who knows your history, medications and other health conditions.

For Australian consumer information: HealthDirect — Hives · Better Health Channel — Hives · Allergy & Anaphylaxis Australia · HAE Australasia.

For an emergency — swelling of the lips, tongue or throat, breathing difficulty, or signs of anaphylaxis — call 000.

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Sources cited

1. ASCIA — Australasian Society of Clinical Immunology and Allergy
2. ASCIA — Acute management of anaphylaxis guidelines
3. Therapeutic Guidelines — eTG complete
4. Australian Medicines Handbook
5. PBS — Pharmaceutical Benefits Scheme
6. TGA — Montelukast Boxed Warning safety update
7. HealthDirect — Hives (urticaria)
8. Better Health Channel — Hives
9. Allergy & Anaphylaxis Australia
10. HAE Australasia
11. EAACI / WAO 2022 chronic urticaria guideline