Allergy Skin Prick Testing

Allergy Skin Prick Testing (OHIP COVERED)

We test for environmental & food allergy.

A skin prick test, also called a puncture or scratch test, checks for immediate allergic reactions to as many as 50 different substances at once. This test is usually done to identify allergies to pollen, mold, pet dander, dust mites and foods. In adults, the test is usually done on the forearm. Children may be tested on the upper back.

Allergy skin tests aren’t painful. This type of testing uses needles (lancets) that barely penetrate the skin’s surface. You won’t bleed or feel more than mild, momentary discomfort. After cleaning the test site with alcohol, the nurse draws small marks on your skin and applies a drop of allergen extract next to each mark. A lancet is used  to prick the extracts into the skin’s surface. A new lancet is used for each allergen.

To see if your skin is reacting normally, two additional substances are scratched into your skin’s surface:

  • Histamine. In most people, this substance causes a skin response. If you don’t react to histamine, your allergy skin test may not reveal an allergy even if you have one.
  • Glycerin or saline. In most people, these substances don’t cause any reaction. If you do react to glycerin or saline, you may have sensitive skin. Test results will need to be interpreted cautiously to avoid a false allergy diagnosis.

About 15 minutes after the skin pricks, the nurse observes your skin for signs of allergic reactions. If you are allergic to one of the substances tested, you’ll develop a raised, red, itchy bump (wheal) that may look like a mosquito bite. The nurse will then measure the bump’s size and record the results.

Allergy Immunotherapy

Allergy Immunotherapy (Allergy Injections)

Allergen immunotherapy is the repeated administration of allergen extracts to people who have known allergies in order to provide long-term relief of symptoms and improvement in quality of life during subsequent natural allergen exposure.

Allergy shots also known as subcutaneous immunotherapy (SCIT), are the most commonly used and most effective form of allergy immunotherapy. This is the only treatment available that actually changes the immune system, making it possible to prevent the development of new allergies and asthma.

Allergy tablets are a form of sublingual immunotherapy (SLIT) that offer a way to treat certain allergies without shots. Like shots, tablets reduce symptoms by helping the body build resistance to the effects of an allergen. Unlike shots, tablets only treat one type of allergen and do not prevent the development of new allergies and asthma.

Allergy drops are another form of SLIT and work the same way as tablets. Drops are widely accepted and used in many countries around the world.

Asthma Testing

This service is currently not being provided due to Covid.

Asthma Testing

It is often not easy for a doctor to make a diagnosis of asthma, as symptoms often come and go. That’s why you should always talk with a doctor preferably an allergist or pulmonologist – who is familiar with asthma diagnosis and treatment guidelines.

To  determine whether asthma or some other cause is responsible for your symptoms, your doctor will use  your family and symptom history; a physical exam and medical tests.

Spirometry Test

If signs begin to point to asthma, your doctor may use a computerized device called a spirometer to check how well your lungs are working. Spirometry is a type of pulmonary function test. You’ll be asked to take a deep breath in and then breathe out as hard as you can into the machine. The spirometer shows the amount of air you are able to breathe in and out and how fast you did it over a certain time period. If your airways are inflamed and narrowed, or if the muscles around your airways tighten up, the results will show it.

Other medical tests may be used to confirm a diagnosis of asthma.

  • Tests for related conditions, such as gastroesophageal reflux disease (GERD) or obstructive sleep apnea
  • A test for sinus disease
  • Allergy testing (skin prick or blood) to determine if allergens are triggering asthma
  • A chest x-ray or electrocardiogram to check for foreign objects in the airways or signs of separate lung or heart disease

Penicillin Allergy Testing

Penicillin Allergy Testing

Immediate allergic reactions to penicillins typically occur quickly (less than an hour) after receiving a dose of the medication, and often occur in patients who have tolerated previous courses of penicillin without issue. Symptoms frequently involve the skin and include:
•    Hives (also known as welts or urticaria, a raised, itchy rash)
•    Swelling commonly around the face and extremities such as hands and feet)

Treatment of these reactions usually involves an antihistamine and sometimes an oral or injected corticosteroid.

In rare cases, more serious reactions that suggest anaphylaxis can occur, including the following:
•    Swelling of the tongue, throat and lips
•    Respiratory symptoms such as difficulty breathing, coughing, chest tightness, wheezing
•    Light-headedness, loss of consciousness (caused by low blood pressure)

These symptoms require immediate treatment with epinephrine, which can be given with an autoinjector if available, and/or at the nearest emergency room or by calling Emergency Medical Services. Additional treatments may include albuterol to treat respiratory symptoms, IV fluids, and corticosteroids.

Penicillin allergy can be evaluated by an allergist / immunologist, who will obtain a careful history and perform skin testing.

This test involves pricking the skin with two forms of penicillins (each of which mimics the forms of penicillin that are found in the blood when a patient takes the drug) and a subsequent intra-dermal test (placing a small amount of each form of penicillin just under the skin). If these tests are negative, it is very unlikely that a penicillin allergy is present. In many instances after negative testing, a dose of an oral penicillin is also given, followed by an observation period. If there is no reaction, the patient is not at risk of having a serious immediate reaction and penicillins can be used thereafter. It typically takes about 2 to 3 hours to perform all of the testing.

In cases of a positive penicillin test, either the skin prick or intra-dermal test will produce a red, raised bump, signifying the presence of an allergy to the medication.

Penicillins need to be avoided and a different antibiotic will be needed to treat infections. If a penicillin is needed, a desensitization procedure can be performed under the care of an allergist / immunologist to temporarily allow the drug to be used.