Allergy
Which Allergy Test Do I Need?
A simple guide to skin prick testing, specific IgE blood testing, and patch testing.
Patient information page | Last reviewed: June 2026
The quick answer
Different allergy tests answer different questions. Skin prick tests and specific IgE blood tests are usually used for immediate-type allergy. Patch testing is used for delayed skin contact allergy. A doctor chooses the test based on the symptoms, the suspected trigger, and the medical history.
Compare the main allergy tests
| Test | Usually best for | What happens | Important limitation |
|---|---|---|---|
| Skin prick test | Immediate allergy, such as some food allergies, pollen, dust mite, mould, or animal dander | Drops of allergen are placed on the skin and gently pricked. Results are usually read after about 15 minutes. | A positive result must match the real-life reaction history. |
| Specific IgE blood test | Food allergy, inhaled allergens, and insect venom allergy | A blood sample is checked for IgE antibodies to a suspected allergen. | It can show sensitisation, but does not always prove clinical allergy. |
| Patch testing | Delayed contact dermatitis from substances touching the skin | Allergens are applied to patches on the back, usually kept on for about 48 hours, with delayed readings over several days. | It is not the usual test for rapid food or pollen-type reactions. |
Skin prick test
What it checks
Immediate-type allergic sensitisation to selected allergens.
What happens
Diluted allergen drops are placed on the skin and gently pricked. A small itchy wheal may appear if the test is positive.
When it is useful
It is often used for suspected food allergy and environmental allergy, including pollen, dust mite, mould, or animal dander.
Limitations
Antihistamines and some skin conditions can affect testing. Results must be interpreted with the history.
Specific IgE blood test
What it checks
IgE antibodies in the blood to a specific suspected allergen, such as egg, peanut, pollen, dust mite, or insect venom.
What happens
A blood sample is taken and sent to a laboratory. Results are not immediate.
When it is useful
It may be used when skin testing is unsuitable, for example with widespread eczema or medicines that interfere with skin testing.
Limitations
A positive result may mean sensitisation only. It does not automatically mean the person will react in real life.
Patch testing
What it checks
Delayed skin allergy, especially allergic contact dermatitis.
What happens
Small amounts of suspected allergens are placed in patches on the back. They usually need to stay dry and in place for about 48 hours.
When it is useful
It is used when skin contact triggers are suspected, such as metals, cosmetics, fragrances, preservatives, rubber, or chemicals.
Limitations
It is for delayed skin reactions. It is not the same as skin prick testing for immediate allergy.
How to prepare
- Write down what symptoms happened and when they started.
- Note suspected triggers, foods, medicines, stings, products, or environments.
- Bring photos of rashes or swelling if you have them.
- List current medicines, including antihistamines and creams.
- Do not stop medicines unless your doctor tells you to.
Questions to ask
- Which test fits my symptoms?
- Do I need to stop antihistamines before testing?
- What does a positive result mean for me?
- Do I need an avoidance plan or emergency plan?
- Should I see an allergy specialist or dermatologist?
A positive test is not always a diagnosis
Allergy tests can show that the immune system recognises a substance. This is called sensitisation. Sensitisation is not always the same as having symptoms when exposed to that substance. Testing is most useful when the result matches a clear medical history.
When to seek urgent help
Seek emergency medical help if allergy symptoms affect breathing, the throat, the voice, alertness, or circulation, or if there is collapse, severe drowsiness, or rapidly worsening symptoms.