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Skin Prick Testing

Skin rashes caused by an allergy are very common. Along with your medical history, allergy tests may be able to confirm whether a particular substance you touch, breathe or eat is causing symptoms.

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At our Worthing and Hove clinics, we provide two types of skin allergy tests: Skin prick testing and Patch testing. No GP referral is required for self-funding patients; for patients using private medical insurance, please check with your insurance provider.

Skin prick testing

Skin prick test is a test for a Type I (immediate) allergic reaction. It is usually triggered by foods or inhaled particles such as pollen or animal fur. It tests for Allergies to Dairy Products, Fruits, Nuts, Cereals, Meats, Pollens, Trees, Animal Furs.

Skin prick tests detect allergies related to diet or anything inhaled that can potentially cause sneezing, asthma, hives or eczema. We can test over 200 allergens by skin prick testing looking for food allergies, nut allergy, pollen allergy and animal allergies. After a consultation with a specialist, who will take your full medical history, allergens are selected for testing.

How is the skin prick test done?

The specialist nurse will then scratch the surface of the forearms and apply the allergens. To see if your skin is reacting normally, two additional substances are scratched into your skin: Histamine and Normal Saline. In most people, there would be an expected reaction to Histamine but not to Saline. We then have to wait 15-20 minutes to look for a visible skin reaction described as a wheel. The doctor interprets the result.  This test typically takes about 30-40min.

Children are usually tested on the upper back rather than forearms.

Is skin prick testing safe?

Generally, yes for both adults and children.

-The most common side effect is slightly swollen, red, itchy bumps on the skin (usually the forearm). These are usually noticeable during the test but in some people, the bumps may last a few days.

-Rarely, the test may elicit a severe, immediate allergic reaction. In such a case, we have the appropriate equipment and medication to deal with such scenarios.

-In certain circumstances, however, your doctor may advise against skin prick testing:  for example, If you have ever had a severe allergic reaction (anaphylaxis) that required A&E admission/ administration of adrenalin. You may be so sensitive to certain allergens that even the tiniest amount used in the skin prick test may trigger a life-threatening reaction (anaphylaxis).

I take medication, would that affect the test?

Some medications could interfere with the test results. If you take antihistamines, antidepressants or any other medication, you must tell the doctor as some medication may need to be stopped temporarily before the test. Antihistamines are usually stopped 7 days before the test. With regards to any other medication please consult with the doctor.

I don’t have any symptoms such as rashes, runny nose, itchy eyes or swelling of the skin, but I just want to know if I have a food allergy. Is this test appropriate?

Probably not. The term allergy has a different meaning to different people. Allergy is often confused with unrelated problems such as food intolerances, neurological or gastrointestinal symptoms.  The skin prick test can only detect a Type I allergic reaction, which manifests with (asthma/hay fever type symptoms- for inhaled allergens or rash, skin swelling and the more severe anaphylactic reaction-for food allergens).

Both, medical history that points towards a Type I allergic reaction and the skin prick test results together can give the most accurate diagnosis. If the doctor doesn’t think your problem is an allergy, he/she may advise you what other tests may be appropriate.

Can a blood test be done to check for food allergies?

Yes, blood tests (in vitro immunoglobulin E Ab tests) are useful for those, who shouldn’t undergo skin tests. They are not done as often, because blood tests can be less sensitive that skin tests and are more expensive.