Today, while new drugs are being developed for the treatment of diseases, allergic reactions occur in our body against these drugs. Drug allergies are not actually a very common allergic disease, but it has become more common with new drugs every day. The diagnosis of drug allergy should be made by an allergist. Skin prick tests, intradermal tests and specific IgE tests in serum are performed for diagnosis. In this article, we have written about how the diagnosis of drug allergy is made.

Diagnosing Drug Allergy

The diagnosis of drug allergy begins with a comprehensive history of the drugs used in the past. However, it is done by determining the examination findings and symptoms compatible with drug-induced allergic reactions. Depending on the history and physical examination results, the diagnosis can be made by performing skin tests, blood tests and drug challange tests. Therefore, if drug allergy is suspected, it is important that an allergist experienced in these diagnostic methods evaluate the patient.

The patient suspected of having a drug allergy should be evaluated. In relation to drugs, the dates of administration of the drug, the formulation of the drug, the dosage and the route of administration, and the clinical symptoms associated with the drug. It should include a detailed history of all prescription and nonprescription medications taken by the patient, including their timing and duration.

In addition to a detailed history, a careful physical examination can identify possible mechanisms underlying the reaction and thus guide further testing for diagnosis.

Skin tests such as skin prick test (SPT) and intradermal tests (test where allergen is injected into the skin), specific IgE tests in serum can be done.

Patch testing involves placing potential allergens on the patient’s back for 48 hours and then evaluating the reactions. Drug patch testing is useful for diagnosing a variety of delayed (type IV) skin reactions, particularly post-drug maculopapular rash, but is generally not useful for diagnosing SJS or TEN.

Recent studies have begun to use the basophil activation test in the diagnosis of drug allergy, as basophils are involved in both immune-mediated and non-immune-mediated reactions. While there is some evidence that the test is useful in evaluating possible allergies to beta-lactam antibiotics, NSAIDs, and muscle relaxants, further confirmatory studies are clearly needed before it can be widely accepted as a diagnostic tool.