Urticaria is commonly referred to as hives which are red and raised circular weal like swellings on the surface of the skin that look like mosquito bites. They range from the size of a pinhead to that of a dinner plate. Although some people can have them every day for weeks, swellings usually disappear within minutes to hours. In most cases hives are not due to allergy and they can be effectively treated with a non-drowsy antihistamine. When hives occur most days for more than 6 weeks this is diagnosed as chronic urticaria, which may require additional medication.
Hives occur in the skin and are common
Up to 20% of people will develop hives at some time during their life. In most cases, hives are not due to allergy. Underneath the lining of the skin and mucosa (gut, lungs, nose and eyes) are mast cells. Mast cells are like land-mines, and contain bags filled with irritant chemicals including histamine. When these are released in small amounts, they cause local itch and irritation, redness and swelling.
Can hives occur anywhere else?
Hives can cause deeper swellings in the skin and mucosa called angioedema. Angioedema most frequently affects the face and lips. Although hives and facial swelling can be uncomfortable and cosmetically embarrassing, they are not usually dangerous. Information on angioedema is available on the ASCIA website www.allergy.org.au/patients/skin-allergy
Hives are rarely due to a serious underlying disease
In many cases a clear cause for a bout of hives in not obvious. Triggers can include: infection, contact with animals or plants and allergic reactions to food, antibiotics or pain killers such as aspirin and other non-steroidal anti-inflammatory drugs (NSAIDs). Sometimes insect stings, food additives or preservatives can also trigger hives. Stress can make established symptoms worse.
Acute bouts of hives due to an allergic reaction can be associated with swelling of the tongue or throat, difficulties breathing and low blood pressure (Anaphylaxis). If signs of anaphylaxis are present urgent medical assessment is required. Information about anaphylaxis is available on the ASCIA website. www.allergy.org.au/patients/about-allergy/anaphylaxis
Hives are not usually painful. Swellings that are painful or leave bruising need to be assessed by a doctor.
Chronic urticaria is diagnosed when hives occur most days for more than 6 weeks
The symptoms of chronic urticaria usually resolve, although this can take months or several years. Most patients manage with appropriate doses of antihistamines. People with severe symptoms interfering with quality of life may be referred to an Allergist/Immunologist or Dermatologist for assessment and consideration of additional medications.
Most people with hives do not need tests
Tests are sometimes done when hives go on for long periods or when unusual symptoms are occurring around the same time. This is to exclude other diseases, which may appear as hives first and other conditions later. Allergy testing is performed when the history suggests an allergic cause.
Treatment of hives
- Most hives resolve within a couple of weeks.
- Avoid aggravating factors Non-specific measures such as avoiding excessive heat, spicy foods or alcohol are often useful.
- Aspirin and other NSAID’s should also be avoided as they often make symptoms worse.
- Medications like antihistamines are often used to reduce the severity of the itch. Severe throat swelling requires early use of medication and attention by your doctor or in hospital.
- Severe chronic urticaria sometimes requires a trial of immune modulators or immunosuppressive medications. Recurrent courses of steroid tablets need to be avoided due to a significant risk of side effects.
- Special diets appear to have a limited role to play in the management of hives. Unfortunately, one cannot predict who will or will not respond to diet on the basis of history or allergy testing. A temporary elimination diet under close medical supervision, followed by challenges may be useful in a small number of cases.
© ASCIA 2017
ASCIA is the peak professional body of clinical immunology/allergy specialists in Australia and New Zealand
This document has been developed and peer reviewed by ASCIA members and is based on expert opinion and the available published literature at the time of review. Information contained in this document is not intended to replace medical advice and any questions regarding a medical diagnosis or treatment should be directed to a medical practitioner. Development of this document is not funded by any commercial sources and is not influenced by commercial organisations.
Content updated 2017