What are hives?
When you have hives (urticaria), you have an itchy rash caused by tiny amounts of fluid that leak from blood vessels just under the skin surface.
Hives can be acute (meaning the rash comes on suddenly and lasts less than six weeks) or chronic (meaning the rash hangs about, on and off, for longer.) This leaflet deals only with hives when they are chronic.
What are the symptoms of hives?
An itchy rash is the main symptom of hives (urticaria). The rash can affect any area of skin. Small raised areas called weals develop on the skin. The weals look like mild blisters and are itchy. Each weal is white or red and is usually surrounded by a small red area of skin which is called a flare. The weals are commonly 1-2 cm across but can vary in size. There may be just a few but sometimes many develop over various parts of the body. Sometimes weals that are next to each other join together to form larger ones. The weals can be any shape but are often round.
As a weal fades, the surrounding flare remains for a while. This makes the affected area of skin look blotchy and red. The blotches then fade gradually and the skin returns to normal. Each weal usually lasts less than 24 hours. However, as some fade away, others may appear. It can then seem as if the rash is moving around the body. The rash may clear completely only to return a few hours or days later.
Are there any other symptoms?
- The appearance of the rash and the itch can cause distress.
- A related condition called angio-oedema occurs from time to time in some people with persistent hives (chronic urticaria). In this condition some fluid also leaks into deeper tissues under the skin, which causes the tissues to swell:
- The swelling of angio-oedema can occur anywhere in the body but most commonly affects the eyelids, lips and genitals.
- Sometimes the tongue and throat are affected and become swollen. The swelling sometimes becomes bad enough to cause difficulty breathing.
- Symptoms of angio-oedema tend to last longer than urticarial weals. It may take up to three days for the swollen areas to subside and go.
- A variation called vasculitic hives occurs in a small number of cases. In this condition the weals last for more than 24 hours, they are often painful, may become dark red and may leave a red mark on the skin when the weal goes. Technically, this type of rash is not urticaria.
Are hives serious?
The rash is usually itchy. Each weal usually lasts less than 24 hours. However, as the rash may constantly come and go, the ongoing itch may cause distress and difficulty sleeping. If there is angio-oedema as well, it can be more serious, as it can cause serious breathing difficulties.
Did you find this information useful?
- BSACI guideline for the management of chronic urticaria and angioedema; British Society for Allergy and Clinical Immunology (Feb 2015)
- Urticaria; NICE CKS, May 2016 (UK access only)
- Zuberbier T, Aberer W, Asero R, et al; The EAACI/GA(2) LEN/EDF/WAO Guideline for the definition, classification, diagnosis, and management of urticaria: the 2013 revision and update. Allergy. 2014 Jul 69(7):868-87. doi: 10.1111/all.12313. Epub 2014 Apr 30.
- Urticaria; DermNet NZ
- Urticaria and angio-oedema: an overview; Primary Care Dermatology Society
- Omalizumab for previously treated chronic spontaneous urticaria; NICE Technology Appraisal Guidance, June 2015
- Sharma M, Bennett C, Cohen SN, et al; H1-antihistamines for chronic spontaneous urticaria. Cochrane Database Syst Rev. 2014 Nov 14 (11):CD006137. doi: 10.1002/14651858.CD006137.pub2.
Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. Patient Platform Limited has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.