Hives (Chronic Urticaria) - Diagnosis

Are any tests needed?

Tests are often not needed or helpful. Which tests are needed depends on the pattern of when the rash comes.

A symptom diary

A symptom diary may be helpful in working out if there is a specific trigger or cause. If your diary shows you only develop the rash on days when you eat a certain food, for example, it may be obvious what the cause is. A diary might also show if the rash relates to stress, exercise or sunlight. It may help rule out certain causes.

Skin-prick allergy tests

In some cases if it appears to be related to an allergy, tests such as skin-prick allergy tests may be helpful. Tiny quantities of substances which might cause an allergy are placed on your skin in a special order. If the skin reacts, you may be allergic to that substance.

Blood tests

In other cases, blood tests for allergy may be useful. In some people, blood tests may help to point to a cause. These may be general blood tests, or blood tests to look for specific proteins produced by your immune system, called autoantibodies. Where these are found, it is likely that it is your own immune system over-reacting which is causing the rash.

Exclusion tests

In some people, 'exclusion' or 'challenge' tests may be needed. For example, testing to see if cold or pressure always causes the rash, or excluding certain foods from the diet to see if that stops the rash from coming back.

Biopsy

Occasionally, if urticarial vasculitis is suspected, a sample of the skin may be taken (a skin biopsy) for further analysis.

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Author:
Dr Mary Harding
Peer Reviewer:
Dr Helen Huins
Document ID:
4449 (v42)
Last Checked:
30 December 2016
Next Review:
30 December 2019

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.