Skin Allergy Testing in Denizli: Prick Test and Patch Test

In an allergy, the immune system mistakes a harmless substance for a threat and reacts against it. The skin is where this reaction is easiest to see, which is why many of the tests used to find the cause of an allergy are done on the skin. The value of a test lies in reading the result alongside your own symptoms.

Which Symptoms Call for an Allergy Test?

An allergy test is meaningful when your history points to a possible cause. In dermatology, these are the main situations in which we consider testing:

• Eczema that develops after contact with a particular product, a metal or a substance at work
• Recurring itchy redness on the face, the hands or the eyelids
• Itching, sneezing and watery eyes linked to a season or a setting
• Hives that appear after a particular food or after contact with an animal

Not every itch or rash is an allergy. We first identify the type of rash at the examination, and only then decide whether a test is needed and which one suits you.

What Is a Skin Prick Test and How Is It Done?

The prick test is a skin test that looks for fast-developing (IgE-mediated) allergies. Drops containing allergens are placed on marked points on the forearm, and the skin under each drop is lightly scratched on the surface with a fine tip. The needle does not go into the skin; what you feel is a brief touch.

If you are allergic, an itchy, raised red patch forms where the drop was placed within about 15 minutes. The size of the swelling is measured and recorded. For comparison, the test also uses two control drops: one that is expected to cause a reaction and one that is not.

Which Allergy Does a Patch Test Show?

The patch test looks for allergic contact dermatitis, which appears days after contact. Nickel, fragrance ingredients, preservatives, hair dye ingredients and rubber additives are among the known causes of this type of allergy. It does not show up in a blood test or a prick test; a patch test is needed for it.

The test substances are placed in small chambers and fixed to the back with tape. The patches usually stay in place for two days. The first reading is done once they are removed, and a second reading a few days later is needed for reactions that appear late.

Can the products I use be added to the test?

In some cases, creams and cosmetics you use or products from your workplace can also be included in the assessment. We discuss which products are suitable at the examination; it helps to bring them in their original packaging.

How Should I Prepare for an Allergy Test?

1. Tell us about every medicine you take. Antihistamines can affect the prick test, and steroid medicines can affect the patch test.
2. Do not apply cream or steroid medicines to the test area for a few days beforehand.
3. Before a patch test, make sure your back has not had strong sun exposure.
4. Make a note of when your symptoms started and of the products you suspect, and bring the notes with you.

The doctor decides whether any medicine needs to be paused. Do not stop regular treatment, such as asthma or heart medicines, on your own.

Are There Any Risks with Allergy Testing?

The expected effect of skin tests is itching and redness at the test sites, lasting a few hours or a few days. In a patch test, a strong reaction can cause a temporary change of colour in that area. A widespread, severe allergic reaction to a prick test is very rare; even so, the test is carried out with the necessary precautions and under a doctor's supervision.

If swelling of the lips or tongue, shortness of breath or dizziness develops after the test, go to the emergency department of the nearest hospital.

How Are Allergy Test Results Interpreted?

A positive result shows that you are sensitised to that substance, but on its own it does not prove that the substance is the cause of your symptoms. We assess the result together with when and how you came into contact with the substance. When a real cause is found, we explain which products contain it and the names it appears under on labels.

In a contact allergy whose cause has been identified by testing, avoiding the substance clearly reduces the eczema. If your itchy rash may have a cause other than eczema, the diagnosis of eczema, hives and other skin diseases becomes part of the same examination. If the diagnosis is still unclear, a small skin biopsy may be considered.

What Is the Difference Between a Blood Test and a Skin Test?

The specific IgE blood test looks for the same kind of fast allergies as the prick test. It may be preferred when widespread eczema makes the skin unsuitable for testing or when antihistamines cannot be stopped. Contact allergy, however, cannot be measured in the blood; a patch test is needed for that.

Skin Allergy Testing in Denizli: Planning Your Test

At our clinic in Denizli, we examine your symptoms and your skin before deciding on an allergy test. We plan which test to use, and with which substances, according to your history, and we interpret the result together with you. If you have recurring itching or eczema, you can contact us for an appointment.