Hives (urticaria)
Also known as: urticaria, nettle rash
Hives, also called urticaria or nettle rash, is an itchy, raised rash that can appear anywhere on the body.
When to seek care
Call 999 if the lips, mouth, throat or tongue suddenly swell, if breathing is very fast or difficult, or if there is sudden confusion or drowsiness. A GP or NHS 111 is the route if the rash has not improved after 2 days, is spreading or keeps returning, or if there is a high temperature and the person feels unwell. Otherwise a GP appointment is the route for hives that continue.
Overview
Hives is an itchy, raised rash that is usually triggered by a reaction to things such as food, pollen, insect bites or chemicals. It can appear anywhere on the body, and it may itch, sting or burn. Swelling deeper under the skin, called angio-oedema, often occurs alongside it. Hives usually gets better within a few days, although it can come back.
Causes
- A reaction to things such as food, pollen, insect bites or chemicals
- Other triggers can include infections, medicines, cold, heat, scratching and pressure from tight clothing
- Some cases have no identifiable cause
Risk factors
- Exposure to a known trigger, such as a food, a medicine or an insect sting
Symptoms
What a clinician may find
- Itchy raised bumps or patches on the skin, which can appear anywhere on the body
- Swelling deeper in the skin (angio-oedema), often of the lips, eyelids or mouth
Complications
- Sudden swelling of the lips, mouth, throat or tongue, which needs a 999 call
- Difficulty breathing, which is among the emergency signs of a serious allergic reaction (anaphylaxis) that needs a 999 call
- Hives that last for six weeks or more, known as chronic urticaria
Diagnosis
Hives is usually recognised from the appearance of the rash and the history, and routine allergy testing is not usually needed. Some blood tests may be used, mainly to rule out other conditions. For some physical types, a provocation test such as an ice cube test may be used.
Treatment
Mild hives often clears within a few days and can often be treated at home, and a pharmacist can advise on antihistamines. If the rash does not clear, a GP may prescribe menthol cream, antihistamines or steroid tablets, and may refer the person to a dermatologist. For longer-lasting hives, first-line treatment is a non-sedating antihistamine, and the aim is to control symptoms until the condition settles. NHS Healthier Together names chlorphenamine and cetirizine among the antihistamines it lists for children. Omalizumab is reserved for severe cases and is available in specialist clinics.
Prevention
Where a trigger is known, avoiding or reducing it is part of care. The BAD leaflet advises avoiding aspirin, ibuprofen and codeine unless essential, because these may aggravate urticaria.
Key facts
| Fact | Detail |
|---|---|
| Also called | Urticaria, nettle rash |
| Main sign | An itchy, raised rash |
| Usual course | Usually better within a few days |
| Chronic form | Lasting six weeks or more |
| First-line treatment of longer-lasting hives | Non-sedating antihistamines |
| Emergency route | Call 999 for sudden swelling of the lips, mouth, throat or tongue, or difficulty breathing |
What are hives and what do they look like?
Hives, or urticaria, is an itchy, raised rash that is usually triggered by a reaction to things such as food, pollen, insect bites or chemicals. The rash can show up anywhere on the body. It may itch, sting or burn.
Some people also have angio-oedema, which is swelling deeper under the skin. The NHS describes angioedema as swelling below the skin's surface that often comes with hives. A person can have hives, angio-oedema or both. Swelling of the lips, eyelids or mouth is typical, and the BAD says it is typically painful rather than itchy. Most urticaria is not inherited. Hereditary angio-oedema is a separate condition that runs in families. Hives usually gets better within a few days.
What triggers hives?
The NHS lists many possible triggers, including certain foods, contact with plants, animals, chemicals or latex, cold, and heat from exercise, emotional stress or spicy food. Medicines, insect stings and infections can also set it off, as can scratching or pressure from tight clothing.
The BAD says the skin's mast cells release histamine, and a specific trigger is often never identified. It also says allergy is not usually the underlying mechanism, and Allergy UK says chronic spontaneous urticaria is not caused by allergy. Some cases have no identifiable cause. Chronic urticaria can be spontaneous, without a specific trigger, or inducible, in reaction to an identifiable trigger. A Leeds Teaching Hospitals leaflet lists heat, cold, pressure and emotion as possible triggers of chronic urticaria.
How long do hives last?
The BAD describes acute urticaria as an episode lasting up to six weeks. Chronic, or long-lasting, urticaria lasts for six weeks or more. Allergy UK says weals must be present daily for at least six weeks to be classed as chronic. In the NHS account, hives usually gets better within a few days.
Chronic spontaneous urticaria means that no specific trigger is found. In about half of the people with chronic spontaneous urticaria, the rash lasts for 6 to 12 months and then gradually disappears. The course in any one person is unpredictable. NICE's clinical experts described chronic spontaneous urticaria as a naturally remitting disease. A very small percentage of people with an urticarial rash have urticarial vasculitis, in which the weals last longer than 24 hours.
How are hives diagnosed?
Diagnosis is mainly clinical, based on a detailed history and the look of the rash, according to Allergy UK and a UK primary care pathway. Allergy UK says clinicians may use a symptom diary. Further tests may include evaluations of the skin, blood and urine, and testing is generally aimed at ruling out other medical conditions.
A UK primary care pathway advises against routinely referring for allergy testing, because the diagnosis is primarily clinical. The BSACI guideline says investigations depend on the clinical history and presentation, and may not be necessary. For physical types, Allergy UK says the diagnosis is usually confirmed through a provocation test such as the ice cube test. The BSACI guideline describes the ice cube test as placing an ice cube in a sealed plastic bag against the skin.
How are hives treated?
The NHS says hives can often be treated at home and that a pharmacist can advise on antihistamines. If the rash does not clear, a GP may prescribe menthol cream, antihistamines or steroid tablets, and may refer the person to a dermatologist.
For longer-lasting hives, the BAD says the aim of treatment is to control symptoms until the condition settles, rather than to cure it. Allergy UK says the first step is a daily non-sedating antihistamine. If that is not enough, it says a leukotriene receptor antagonist can be tried, and a one-off short course of steroid tablets may be offered for severe flare-ups. The BAD says omalizumab is limited to severe chronic spontaneous urticaria and is available only in specialist clinics. Allergy UK says that if initial treatment is ineffective, GPs should refer people to a specialist dermatologist or immunologist. NHS Healthier Together names chlorphenamine and cetirizine among the antihistamines it lists for children.
Living with hives and when to get help
The BAD leaflet advises avoiding aspirin, ibuprofen and codeine unless they are essential, because they may make urticaria worse.
The NHS says to call 999 if the lips, mouth, throat or tongue suddenly swell, if breathing is very fast or difficult, or if there is sudden confusion or drowsiness. It advises contacting a GP or NHS 111 if the rash has not improved after 2 days, is spreading or keeps returning, or if there is a high temperature and the person feels unwell. For children, NHS Healthier Together advises contacting a GP if symptoms last longer than six weeks, are hard to control even with regular antihistamines, or if there is swelling without hives. Breathing problems with hives need urgent medical help, and the route is a 999 call.
Frequently asked questions
What causes hives?
The NHS says hives is usually triggered by a reaction to things such as food, pollen, insect bites or chemicals. Other triggers include infections, medicines, cold, heat, scratching and pressure from tight clothing. Some cases have no identifiable cause, according to the BAD, which says a specific trigger is often never identified.
How long do hives last?
The NHS says hives usually gets better within a few days. The BAD describes acute urticaria as lasting up to six weeks and chronic urticaria as lasting six weeks or more. In about half of people with chronic spontaneous urticaria the rash clears within 6 to 12 months, but the course in any one person is unpredictable.
When are hives an emergency?
The NHS says to call 999 if the lips, mouth, throat or tongue suddenly swell, if breathing is very fast or difficult, or if there is sudden confusion or drowsiness. The BAD also says breathing problems need urgent medical help, so the route is a 999 call.
Are hives caused by an allergy?
Allergy is not usually the underlying mechanism, according to the BAD, although hives can follow a reaction to things such as food, pollen or insect bites, as the NHS describes. Allergy UK says chronic spontaneous urticaria is not caused by allergy, so elimination diets are not a standard approach.
What is the difference between hives and angio-oedema?
Hives is a rash on the skin surface, while angio-oedema is swelling deeper under the skin. The NHS says angioedema often comes with hives, and the BAD says angio-oedema typically affects the eyelids, lips or mouth.
Connected pages in detail
What each linked page on Anatomy Nexus covers, in a line, for Hives (urticaria).
Symptoms
- Rash Any change in the colour or texture of the skin.
- Swelling (oedema) Excess fluid in the tissues.
Medications
- Cetirizine and antihistamines A second-generation (less sedating) antihistamine that blocks histamine H1 receptors to relieve hay fever, hives and other allergic symptoms.
- Chlorphenamine A first-generation antihistamine, sold over the counter, that relieves hay fever.
Guides and news
- MHRA approves remibrutinib for urticaria The MHRA has approved remibrutinib (Rhapsido) tablets for adults with chronic spontaneous urticaria whose symptoms antihistamines do not control…