Oral Challenge Test, Oral Provocation Test
For oral food or drug allergy test, you ingest a food or drug in a capsule or in its natural form, and a physician observes you for the development of typical allergic symptoms. Food allergies can usually be detected using various dietary methods, in which the suspected food is excluded from the diet for a certain period of time and then reintroduced to see if symptoms appear. Oral food or drug allergy test is typically ordered only if the results from such dietary techniques—as well as from blood and skin allergy tests—are inconclusive or negative, but an allergy or intolerance is still suspected.
Purpose of the Oral Food or Drug Allergy Tests
- To confirm a suspected allergy or intolerance to a particular food or food additive
- To confirm a suspected allergy or intolerance to certain medications, such as nonsteroidal anti-inflammatory drugs
- To accurately diagnose bad reactions to foods
Who Performs Oral Food or Drug Allergy Tests
- A physician
Special Concerns about Oral Food or Drug Allergy Tests
- If you are currently experiencing a severe cold, diarrhea, or other digestive problems, the test should be postponed until your condition improves.
- This test should not be performed if you have previously experienced a severe, life-threatening allergic reaction to the food or drug in question.
- Risky challenge tests are often done in special research units or hospitals.
Before the Oral Food or Drug Allergy Test
- Avoid all of the foods or drugs that are suspected of causing an allergic reaction for 1 to 2 weeks prior to testing, according to your doctor’s instructions.
- Stop taking antihistamines or other drugs that might suppress your allergic response prior to the test, according to your doctor’s instructions.
- You should only get the test on a day that you are not experiencing allergic symptoms. Fast before the test to ensure that no food/drink is in your system that could affect results
What You Experience
- You will be asked to swallow liquid or solid foods or test capsules containing the suspected food or drug at specific time intervals.
- You will then be observed for any evidence of an allergic reaction to the test substance. Possible responses include hives; itching; wheezing; swelling of the eyes, lips, face, or tongue; nasal irritation; or gastrointestinal symptoms such as nausea, diarrhea, and abdominal pain.
- To ensure objective results, the test may be performed twice. One of these times, you will ingest a placebo capsule containing a harmless substance, usually sugar. (A third party labels the capsules so that neither you nor your physician knows which of the test capsules is the placebo.)
- Depending on the nature and the severity of the expected allergic reaction, you may be observed for a period ranging from few minutes to several hours.
Risks and Complications of Oral Food or Drug Allergy Tests
- There are several serious risks associated with this test, including a life-threatening response called anaphylactic shock (characterized by symptoms such as respiratory distress, decreased blood pressure, and shock); acute asthma; urticaria (hives or wheals); and angioedema (a sudden swelling involving the lips and skin, mucous membranes, and sometimes the abdominal organs).
- In the event that complications arise, emergency medications and equipment are kept readily available.
After the Oral Food or Drug Allergy Test
- You will be asked to remain at the testing facility until the risk of an acute allergic reaction has passed.
- If this test does result in allergic symptoms, they may persist for several hours or even days.
- Inform your doctor immediately if you develop any symptoms after leaving the testing area.
Oral Food or Drug Allergy Test Results
- The doctor will assess your response to the various test substances. This test is considered positive if you develop typical allergic symptoms after ingesting the potential allergen, but not after taking the placebo capsule.
- If a specific allergy is diagnosed, your doctor will advise you to avoid the food or drug that is causing your symptoms.
- A negative result with this test is usually considered conclusive, and no further tests are needed.
The Johns Hopkins Consumer Guide to Medical Tests
Simeon Margolis, M.D., Ph.D., Medical Editor
Updated by Remedy Health Media