Quick answer. Hives (urticaria) are raised, itchy welts (wheals) that can appear anywhere on the skin and usually come and go within hours, sometimes with deeper swelling of the lips or eyes (angioedema). Acute hives (under 6 weeks) are often triggered by viral infections, foods, medicines or insect stings, while chronic hives (over 6 weeks) are usually spontaneous with no identifiable allergen and are typically NOT a food allergy. The mainstay of treatment is non-drowsy antihistamines (the dose may be raised under medical advice for chronic cases), with specialist options such as omalizumab for difficult chronic urticaria. Most hives are not dangerous, but hives WITH difficulty breathing or swelling of the throat or tongue signal anaphylaxis, a life-threatening emergency – call 995 immediately.
Hives, known medically as urticaria, are one of the most common skin complaints in Singapore, and most people will have an outbreak at some point in their lives. They are usually harmless and settle on their own, but they can be intensely itchy and, occasionally, a sign of a serious allergic reaction. This guide explains what causes hives, how acute and chronic urticaria differ, how they are treated, and, most importantly, the warning signs that mean you should call 995.
At a glance
| Type / aspect | What it involves | Notes |
|---|---|---|
| Acute urticaria | Hives lasting less than 6 weeks | Often from viral infection (~40%), foods, medicines or insect stings; usually self-limiting |
| Chronic urticaria | Hives lasting more than 6 weeks, often near-daily | Usually spontaneous with no allergen found; typically NOT a food allergy; usually settles over time |
| Inducible urticaria | Hives triggered by a physical stimulus | E.g. scratching (dermographism), cold, heat, sweat, pressure or sunlight; avoid the trigger |
| Angioedema | Deeper swelling of lips, eyes, hands or feet | Looks alarming but usually not dangerous on its own; settles in 24-48 hours |
| Anaphylaxis (EMERGENCY) | Hives with breathing difficulty, throat/tongue swelling, dizziness or collapse | Life-threatening; needs adrenaline now – call 995 |
| First-line treatment | Non-drowsy antihistamines | Daily or as needed; dose may be raised up to ~4x under medical advice; omalizumab for refractory chronic cases |
What hives (urticaria) actually are
Hives are localised, itchy pink or pale-red swellings of the skin called wheals. They can appear anywhere on the body, are often round or ring-shaped, and tend to come and go: an individual wheal usually fades within 24 hours, though new ones can keep appearing elsewhere.
Hives form when special immune cells in the skin (mast cells) release histamine and other chemicals, which make small blood vessels leak fluid and produce the raised, itchy welts. When this swelling happens in deeper, looser tissue, such as around the eyes, lips, hands or feet, it is called angioedema. Angioedema looks more dramatic and may take 24 to 48 hours to settle, but on its own it is usually not dangerous.
Acute vs chronic urticaria
Doctors divide hives by how long they last:
- Acute urticaria (less than 6 weeks): the most common form. It is often set off by a viral infection (around 40% of acute cases), and sometimes by foods, medicines (such as antibiotics or painkillers), or insect stings. It usually clears within days to a few weeks.
- Chronic urticaria (more than 6 weeks): hives that recur or persist, often almost daily, for months or years. Most chronic cases are spontaneous, meaning no specific trigger or allergen can be found despite testing.
An important point that surprises many people: chronic urticaria is usually NOT caused by a food allergy. Chasing endless food-elimination diets rarely helps. Some people do have inducible hives triggered by a physical stimulus, such as scratching/rubbing (dermographism), cold, heat, sweating, pressure or sunlight, and identifying these can guide simple avoidance.
When hives are an emergency: anaphylaxis
Most hives are not dangerous. But hives can occasionally be the first sign of anaphylaxis, a severe, life-threatening allergic reaction. Anaphylaxis needs immediate adrenaline (epinephrine) and emergency care.
Call 995 immediately (or use an adrenaline auto-injector if prescribed) if hives appear together with any of these:
- Difficulty breathing or wheezing
- Swelling of the throat, tongue or mouth, or trouble swallowing
- A hoarse or muffled voice
- Dizziness, faintness or collapse (a sign of low blood pressure)
- Widespread swelling of the face or body, especially after a known trigger such as a food, drug or insect sting
Do not wait to see if it passes. Anaphylaxis can worsen within minutes.
How hives are treated
For ordinary hives, the goal is to control the itch and swelling while the condition runs its course:
- Non-drowsy (second-generation) antihistamines are the cornerstone of treatment. They are taken daily or as needed to reduce itch and wheals.
- Higher doses for chronic cases: if standard doses are not enough, a doctor may increase the antihistamine – up to about four times the usual dose – or combine medicines, before stepping up further.
- Specialist (biologic) treatment: for difficult chronic urticaria that does not respond to antihistamines, a dermatologist or allergist may prescribe omalizumab, an injectable biologic. Short courses of oral steroids may be used for severe flares, but not long term.
Self-care helps too: use cool compresses, mild cleansers and moisturisers, avoid hot showers and tight clothing, and limit known aggravators such as alcohol and NSAID painkillers (paracetamol is usually a safer choice). Keeping a symptom and food diary with photos can help your doctor spot patterns.
Chronic urticaria: frustrating but usually not dangerous
Living with chronic hives can be exhausting and demoralising, but it is reassuring to know that chronic urticaria is usually not dangerous and does not damage internal organs. In most people it eventually settles on its own over months to a few years, even if the exact cause is never found. Effective antihistamine treatment in the meantime can keep symptoms well controlled so you can sleep and function normally.
When to see a doctor in Singapore
See a GP if your hives are bothersome, keep recurring, or are not controlled by over-the-counter antihistamines. Your GP can prescribe stronger or higher-dose non-drowsy antihistamines and look for obvious triggers.
Ask for referral to a dermatologist or allergist (for example at the National Skin Centre or a hospital allergy service) if hives last more than 6 weeks, recur often, are severely affecting sleep or daily life, or are not improving on increased antihistamine doses, as specialist options such as omalizumab may be considered.
Go straight to A&E or call 995 for any hives accompanied by breathing difficulty, throat or tongue swelling, a hoarse voice, dizziness/fainting, or rapidly spreading swelling – these are signs of anaphylaxis.
Related guides
- Best Dermatology Clinics in Singapore — our editorial shortlist
- dermatology clinics directory
- Psoriasis treatment
- Rosacea treatment
- Fungal skin infections
Sources
- National Skin Centre (NSC) – Urticaria
- SingHealth – Hives (Urticaria) and Angioedema
- SingHealth – Urticaria (Hives)
- HealthXchange.sg (SingHealth) – How To Manage Hives (Urticaria) and Angioedema
- Dermatological Society of Singapore – Understanding and Managing Urticaria
Related conditions & guides
Related conditions and guides you may find useful:
- Allergic Rhinitis (Nose Allergy) in Singapore
- Allergy Testing & Immunotherapy in Singapore
- Anaphylaxis in Singapore
- Childhood Eczema and Allergies in Singapore
- Drug Allergy in Singapore
- Eczema (Atopic Dermatitis) Treatment in Singapore
Part of our Skin health guides · Browse all health topics