Urticaria (hives) — what causes it, what helps, and when chronic itching is more than just an allergy

About this guide

Urticaria — the medical term for hives — is one of the most common conditions we see, and one of the most consistently misunderstood. Patients arrive convinced their hives are caused by a specific food, a soap, or “an allergy” — and they often spend months tracking and eliminating possible triggers without success. The much more common reality, especially when hives last more than a few weeks, is that there is no identifiable trigger, and the focus should shift from hunting for a cause to controlling the symptoms reliably with the right medication regimen.

This guide covers:

• What hives actually are — wheals, the mast cell, and why “allergy” is often the wrong frame
• Acute vs chronic — and why the 6-week mark matters
• What we look into for chronic urticaria — limited blood tests, focused history, what we don’t routinely test
• Angioedema — when swelling is a more serious problem
• The antihistamine ladder — first-line, escalating to four times the licensed dose, then add-on options
• When we refer for biologics (omalizumab) — and why it’s worth it for the right patients
• Things that may not help — including indiscriminate elimination diets
• When to come and see us — and when it’s an emergency

It sits alongside our allergic rhinitis guide — the antihistamines you’ll hear about overlap, but the conditions and dosing strategies are quite different.

What urticaria actually is

A hive (also called a wheal) is a transient raised, itchy, often pink or pale-red swelling in the skin that typically lasts less than 24 hours in any one spot — moving and changing day to day. The biology underneath:

• Mast cells — immune cells in the skin — release histamine and other inflammatory mediators
• This causes leaky small blood vessels in the skin, producing the swelling, redness, and itch
• Each individual wheal usually settles within 24 hours and leaves no mark, even though new wheals continue to appear elsewhere

Why “allergy” is often the wrong frame:

• A true allergic reaction (IgE-mediated) requires repeated exposure to a specific trigger
• The mast cell can release histamine for many reasons that aren’t allergic — viral infections, certain medications acting on mast cells directly (e.g. some painkillers, opioids, contrast dyes), pressure or scratch on the skin, heat, cold, exercise, and autoimmune triggers where the body’s own antibodies activate mast cells without any external trigger at all
• In chronic urticaria (lasting more than 6 weeks), the cause is usually autoimmune or idiopathic — not an allergy at all

This matters because it changes the conversation from “what is causing this?” (often unanswerable) to “how do we get this under control?” (almost always achievable with the right regimen).

Acute vs chronic — the 6-week rule

The arbitrary but useful definition:

• Acute urticaria — lasts less than 6 weeks. Common; often follows a viral infection, sometimes a medication, occasionally an identified food. Usually self-limiting.
• Chronic urticaria — wheals occurring on most days for more than 6 weeks. Affects about 1% of people at some point. Mostly chronic spontaneous urticaria (no identifiable trigger); a smaller proportion is chronic inducible urticaria (triggered reproducibly by a physical stimulus).

Acute urticaria mostly settles by itself. Chronic urticaria needs a structured, longer-term approach.

Acute urticaria — usually a transient problem

Most acute urticaria episodes:

• Follow a viral infection — a few days of hives during or just after a cold, sore throat, or flu-like illness is very common
• Sometimes follow a medication — antibiotics (particularly penicillins), NSAIDs (like aspirin or ibuprofen), opioids
• Occasionally follow a specific food — but only if hives appear consistently within 1–2 hours of the same food on multiple occasions, with no other apparent trigger. Random food associations during a 2-week hive episode are usually coincidence rather than allergy.
• Resolve spontaneously over days to weeks

Treatment is regular daily second-generation antihistamine for the duration of the episode (not “as needed” — daily blocking is more effective). If severe with very widespread wheals, swelling, or significant impact, a short course of oral prednisolone can shorten the episode (we use this judiciously — see below).

If the episode settles within 6 weeks and doesn’t return, no further workup is needed. If it persists or recurs, we move into the chronic urticaria pathway.

Chronic urticaria — the bigger picture

Chronic urticaria affects about 1% of people at any given time. It tends to fluctuate in severity, can be daily or intermittent, and most cases resolve spontaneously over time — about half settle within 1–2 years, and most by 5 years, though some patients have it longer.

There are two main types:

Chronic spontaneous urticaria (CSU)

By far the most common form. Wheals appear without any identifiable trigger. About 30–50% of cases are autoimmune — antibodies against the IgE receptor on mast cells trigger histamine release. Many cases are simply idiopathic (cause unknown).

Important to be honest with patients: we don’t always find a cause, and we usually don’t need to. The treatment ladder works whether or not we identify a trigger.

Chronic inducible urticaria (CIndU)

Wheals appear reproducibly in response to a physical trigger:

• Dermographism — wheals appear along scratched lines on the skin (the most common)
• Cold urticaria — triggered by cold air, cold water, or holding a cold object
• Heat urticaria — triggered by warmth (rare)
• Pressure urticaria — wheals develop hours after sustained pressure (e.g. tight waistband, prolonged sitting)
• Solar urticaria — sun exposure
• Cholinergic urticaria — small monomorphic wheals triggered by sweating (exercise, hot showers, emotional stress)
• Aquagenic urticaria — water itself, regardless of temperature (rare)

For CIndU, the trigger is usually identifiable from history. Specialist physical urticaria testing (e.g. cold provocation, dermographometer) is sometimes useful for confirmation and for assessing severity — we don’t perform these tests in our clinic and would refer you to a dermatologist if formal testing is indicated.

Workup for chronic urticaria — what we test, what we don’t

A focused, targeted workup is more useful than extensive testing. For most patients with chronic urticaria, we typically check:

• Full blood count (FBC) — for eosinophilia, signs of infection or other haematological clues
• ESR or CRP — markers of inflammation
• Thyroid function (TSH) — autoimmune thyroid disease is associated with chronic spontaneous urticaria
• Liver function tests (LFT) — baseline before starting medications
• Total IgE — sometimes useful; particularly relevant if biologic therapy is being considered

We don’t routinely order:

• Specific IgE / RAST testing for food panels — high false-positive rate; food allergy is rarely the cause of chronic urticaria; testing leads to unnecessary food avoidance
• Allergy skin-prick testing — same logic; reserved for cases where the history clearly suggests a specific allergic trigger
• Extensive autoimmune panels unless other clues suggest a systemic autoimmune condition
• Helicobacter pylori testing routinely — historical association is weak; only if symptoms suggest gastritis

If your history clearly suggests a specific trigger (e.g. wheals consistently within 1–2 hours of the same food on multiple occasions), we may target testing or trial elimination. Otherwise, the workup stays focused.

Angioedema — when the swelling is deeper

Angioedema is deep swelling of skin or mucous membrane — typically of the lips, eyes, hands, feet, or genitals. It can occur with hives or independently. Lasts longer than wheals (usually 24–72 hours) and tends to be uncomfortable rather than itchy.

Two important distinctions:

Histamine-related angioedema (the common type)

Often part of an urticaria episode; responds to antihistamines. Self-limiting.

ACE inhibitor-related angioedema

Patients on ACE inhibitors (lisinopril, enalapril, perindopril, ramipril) — common blood pressure medications — can develop angioedema, sometimes years into treatment. Often involves the face, lips, tongue, or throat. Does not respond to antihistamines or steroids. The treatment is to stop the ACE inhibitor permanently and switch to an alternative (usually an ARB, though small risk of cross-reaction).

If you have angioedema and are on an ACE inhibitor, we will stop it and switch — please do not restart it on your own.

Hereditary angioedema (rare but important)

A rare genetic condition with recurrent angioedema (often facial, abdominal, or laryngeal) without urticaria, often with a family history. Doesn’t respond to antihistamines or steroids; requires specialist treatment with C1-esterase inhibitor or related agents. If we suspect this — particularly recurrent angioedema without wheals, family history, or attacks involving the gut or throat — we refer to allergy/immunology.

Urgent — angioedema involving the throat is an emergency

Throat or tongue swelling, voice change, difficulty swallowing, or any breathing difficulty — call 995 immediately or go to the nearest emergency department. Don’t wait.

The treatment ladder — step by step

Modern urticaria treatment follows an internationally-agreed step-up approach (EAACI / WAO guidelines, 2022). The goal is complete control — no wheals, no itch — with the minimum effective treatment.

Step 1 — Second-generation H1 antihistamine at the licensed dose

The mainstay. We typically choose from:

• Cetirizine 10 mg once daily
• Loratadine 10 mg once daily
• Fexofenadine 180 mg once daily
• Bilastine 20 mg once daily (newer; well-tolerated, no major drug interactions; less commonly stocked locally)
• Desloratadine 5 mg once daily

Important points:

• Take regularly, every day — not “as needed.” Hives respond to continuous antihistamine blockade, not intermittent rescue dosing.
• Second-generation, not first-generation. Older sedating antihistamines (chlorpheniramine, hydroxyzine, diphenhydramine) are not preferred because of drowsiness and other side effects, and the second-generation agents are at least as effective.
• Trial for 2–4 weeks at this dose. If incompletely controlled, move up.

Step 2 — Increase the dose, up to four times the licensed dose

If standard dose isn’t controlling the urticaria, the same agent at up to four times the licensed dose is internationally recommended (off-label in most labels, but well-evidenced and standard practice — EAACI Guideline 2022).

For example: cetirizine 10 mg morning + 10 mg evening + 10 mg evening + 10 mg morning = 40 mg total daily, divided.

This is genuinely effective for many patients who didn’t respond at standard dose. Common side effects (drowsiness, dry mouth) sometimes appear at higher doses but are usually mild and tolerable.

We discuss this at the visit — including the off-label nature — and document agreement to escalate.

Step 3 — Add-on options

If high-dose antihistamine still doesn’t fully control symptoms:

• Add an H2 antihistamine — famotidine 20 mg twice daily (or ranitidine where still available). Modest additional benefit; well-tolerated.
• Consider montelukast 10 mg at night — this is a leukotriene receptor antagonist used in asthma. It is a possible add-on option for refractory urticaria but we don’t routinely use it because of the FDA black-box warning (2020) about neuropsychiatric side effects — sleep disturbance, mood changes, and in rare cases suicidal ideation. We discuss the risks and benefits carefully if we consider it, and it would be an informed choice rather than first-line.

Step 4 — Refer for biologic therapy (omalizumab)

For chronic urticaria that remains active despite Steps 1–3, we refer to dermatology for consideration of:

• Omalizumab (Xolair) — an anti-IgE monoclonal antibody injection, given subcutaneously every 4 weeks. Highly effective for chronic spontaneous urticaria — many patients achieve complete control. Specialist-led; needs ongoing administration and monitoring; cost is significant but coverage may apply through some insurance plans.
• Other immunomodulators — ciclosporin and a few others have a role in selected cases; specialist territory.

Many of our patients we refer for omalizumab tell us afterwards that they wished they’d been referred earlier. If your urticaria is genuinely affecting daily life despite Steps 1–3, please tell us — we will refer rather than ask you to keep tolerating it.

Severe acute flares — short prednisolone bursts

For severe acute urticaria with widespread wheals, marked discomfort, or significant interference with daily life, a short oral prednisolone burst (typically 30–40 mg daily for 3–5 days, no taper needed at this short duration) can dramatically shorten the episode. We are comfortable prescribing this when clinically warranted.

We use prednisolone judiciously — not for chronic urticaria control (long-term oral steroids carry their own risks and don’t address the underlying problem), and not for mild acute episodes that will settle with antihistamines alone. The right time for a prednisolone burst is the severe, debilitating acute flare.

Adrenaline auto-injectors — when they’re appropriate

Patients sometimes ask about adrenaline auto-injectors (EpiPen, Anapen). These are for anaphylaxis — a different, life-threatening allergic reaction involving multiple body systems (skin, breathing, blood pressure, gut). They are not generally indicated for urticaria, even severe urticaria.

Adrenaline is appropriate if you have:

• A history of anaphylaxis (not just hives) to a known trigger
• Hives plus throat tightness, breathing difficulty, dizziness, or vomiting after exposure to a specific trigger

If you carry an adrenaline pen, we will check you know how to use it, when to use it, and that it’s in date. If you are uncertain whether you should have one, please ask.

Things that may not help

Worth being honest about:

• Indiscriminate elimination diets — cutting out multiple food groups in chronic urticaria almost never helps. Short-term placebo response is common; long-term benefit is rare; nutritional risk is real.
• “Detox” or anti-inflammatory protocols — no evidence in urticaria.
• Probiotics — limited evidence.
• Antifungals or antibiotics for unproven H. pylori or “candida” — not supported.
• Stopping all medications “in case they’re the cause” — sometimes a trial removal of a specific suspect (NSAID, ACE inhibitor) is sensible; blanket discontinuation of essential medications is not.
• Antihistamines as needed only — under-treats the condition; daily is more effective.
• First-generation sedating antihistamines as primary treatment — not recommended; second-generation are at least as effective and better-tolerated.

If something has clearly helped for you, please tell us — we’d rather hear about it than have you stop mentioning it.

When to come and see us

Worth a clinic visit if:

• Hives have been daily or near-daily for more than 2–4 weeks — we should review and start a structured treatment plan, not leave you on rescue antihistamines indefinitely
• Standard antihistamine isn’t working — we have a clear ladder to escalate
• You’ve had angioedema — particularly facial — and are unsure why
• You’re on an ACE inhibitor and have had angioedema — we need to switch your blood pressure medication
• Your urticaria is significantly affecting sleep, work, school, or mood — this is treatable and shouldn’t be tolerated
• You’ve been doing your own elimination diet — let’s reassess and target investigation properly
• You’ve had urticaria with breathing difficulty, throat tightness, or dizziness — even once — please come in or attend A&E

Urgent — call 995 or attend the nearest emergency department

• Throat swelling, voice change, difficulty swallowing, breathing difficulty, wheezing, or feeling faint with urticaria — this may be anaphylaxis. Use your adrenaline auto-injector if you have one, and call 995 immediately. Do not drive yourself.

Get in touch

Joo Chiat — 172 Joo Chiat Road, #01-01, Singapore 427443 · Tel 6920 1952

Punggol — 658 Punggol East, #01-04, Singapore 820658 · Tel 6312 4589

Email — admin@ktmc.sg

References

Guidelines and consensus statements

• Zuberbier T, Abdul Latiff AH, Abuzakouk M, et al. The international EAACI/GA²LEN/EuroGuiDerm/APAAACI guideline for the definition, classification, diagnosis, and management of urticaria. Allergy. 2022;77(3):734–766.
• Bernstein JA, Lang DM, Khan DA, et al. The diagnosis and management of acute and chronic urticaria: 2014 update. American Academy of Allergy, Asthma & Immunology / Joint Task Force on Practice Parameters. J Allergy Clin Immunol. 2014;133(5):1270–1277.
• Powell RJ, Leech SC, Till S, et al. BSACI guideline for the management of chronic urticaria and angioedema. Clin Exp Allergy. 2015;45(3):547–565.

Omalizumab and biologic therapy

• Maurer M, Rosén K, Hsieh HJ, et al. Omalizumab for the treatment of chronic idiopathic or spontaneous urticaria. N Engl J Med. 2013;368(10):924–935.
• Kaplan A, Ferrer M, Bernstein JA, et al. Timing and duration of omalizumab response in patients with chronic idiopathic/spontaneous urticaria. J Allergy Clin Immunol. 2016;137(2):474–481.

Montelukast safety

• U.S. Food and Drug Administration. FDA requires Boxed Warning about serious mental health side effects for asthma and allergy drug montelukast (Singulair). FDA Drug Safety Communication, March 2020.

Hereditary angioedema

• Maurer M, Magerl M, Betschel S, et al. The international WAO/EAACI guideline for the management of hereditary angioedema — the 2021 revision and update. Allergy. 2022;77(7):1961–1990.

This information is for general education only and is not a substitute for medical advice. Urticaria management is individualised — please attend a consultation for assessment. v1.0 · April 2026 · Review due April 2028.