The skin prick test is a very common test to identify whether a certain substance causes the allergies in a person. It is done commonly in the clinic setting and results are available within 20 minutes.
Many common food products, animal allergens and household allergens can be tested. Allergens such as dust mites, house dust, fungus and cockroach are commonly found at home and care can be taken to minimize the contact and allergy exposure.
Pets are also a source of allergens especially cats and dogs that can be easily identified and readily avoided to reduce symptoms associated with allergy.
Some common food allergy in children include egg, fish and peanut. In some adults, food allergy to shellfish, tree nuts, soy or certain fruits may be identified.
In our clinic, we commonly perform skin prick test in children and adults with allergic rhinitis, asthma or suspected food allergy. Once the allergens are identified, we can take the appropriate measures to reduce exposure to allergens and to optimize the management of allergic rhinitis and asthma.
Allergy is not an uncommon medical problem. We are seeing more children with food allergy and more adults with allergic rhinitis and asthma in Singapore. An allergy is an abnormal reaction by a person’s immune system against a usually harmless substance. It maybe something you ate, inhaled or touched that causes the allergic reaction. A person without allergies would have no reaction to this substance, but when a person who is allergic encounters the trigger, the body reacts by releasing chemicals which cause allergy symptoms. These symptoms can range from running nose, rashes, watery itchy eyes, asthma attacks, urticaria to life-threatening anaphylaxis.
Skin prick testing is generally safe and reliable for both children and adults. It is considered to be the most convenient and immediate. It is least expensive to determine the allergen that one is allergic to. Sometimes, we do blood allergen assay (Ig E) but this is more costly, less sensitive and requires a few days for the results to be back.
During the skin prick test, a very small amount of certain allergens is introduced to the skin by pricking on the surface on the skin (forearm or back of the person) using disposable pricks.
After the pricking is done, reaction will occur within 15 minutes if there is allergy. It will be a little swelling at the spot where the allergen was introduced, associated with itchiness and redness around the same area. The swelling will subside in about 2 to 3 hours’ time.
Patients are advised to see a doctor before doing the test as there are certain medications like antihistamine to withhold to ensure accuracy of the test. Pregnant ladies are not advised to do the test. Children as young as 6 months can undergo these allergy tests.