Penicillin allergies have been notoriously over diagnosed. This means that many individuals were told to avoid the drug, often having to settle for more expensive and less efficient treatment alternatives. Fortunately, there are a few simple tests that can be used to confirm your diagnosis.
Medical History Review
First, your doctor will review your medical history. They are specifically looking for details about the last time you experienced a penicillin-induced allergic reaction, including the type and severity of your symptoms. This is important information, as your doctor will need to confirm your symptoms were mild enough to continue with the testing.
Skin Prick Test
The first method of testing is the skin prick test. A drop of penicillin extract is placed on the skin and a small needle pricks the top layer of skin through the drop. After 15 minutes any reaction, such as red, itchy bumps, is measured. A positive reaction indicates a high likelihood of a penicillin allergy. Additional tests are typically still completed even when there is a negative reaction from the skin prick test.
Intradermal Skin Test
An intradermal skin test is completed next. An intradermal wheal, or bleb, is injected directly under the top layer of skin. After 15 minutes, any reactions are measured and classified as either positive or negative. If the results from this test are still negative, an oral challenge can then be performed.
An oral challenge is the final test to rule out a penicillin allergy. This test is performed in a medical setting with continuous medical oversight. This ensures if you do experience a reaction, it can be treated immediately. During this challenge, you will ingest a single dose of penicillin and will then be monitored for at least an hour. If you can tolerate the dose without a reaction, your doctor will be able to confirm you are officially not allergic to penicillin.