Can drug allergy skin testing induce an allergic reaction?

From the Guidelines

Drug allergy skin testing can potentially induce an allergic reaction, though severe reactions are rare when testing is performed properly. The risk of an allergic reaction during skin testing is a concern, but it is relatively low, with severe reactions occurring in approximately 1-3% of cases 1. Skin testing involves exposing small amounts of the suspected allergen to the skin through prick tests or intradermal injections, starting with highly diluted concentrations, as seen in the guidelines for cephalosporin skin testing 1.

Key Considerations

• The risk of reaction is higher in patients with a history of severe reactions, those with unstable asthma, or when testing with certain high-risk medications like antibiotics or chemotherapy agents.
• Patients should remain under observation for at least 30 minutes after testing to monitor for delayed reactions.
• Despite these risks, when performed correctly, drug allergy skin testing provides valuable information that can help clarify true drug allergies and potentially avoid unnecessary medication restrictions.
• A recent systematic review found that the incidence of life-threatening reactions to penicillin was very low (< 1–3/1000 individuals treated) and that confirmation of penicillin allergy diagnosis or delabeling using direct oral drug challenge or penicillin skin testing seems to be safe and is associated with a low rate of adverse reactions 1.

Recommendations for Practice

• Skin testing should only be performed by healthcare providers with experience in allergy testing, with emergency medications and equipment readily available.
• The use of highly diluted concentrations for initial testing, as outlined in guidelines for drugs like cephalosporins 1, can help minimize the risk of severe reactions.
• Patients should be fully informed of the potential risks and benefits of skin testing before proceeding.

From the Research

Drug Allergy Skin Testing

• Drug allergy skin testing is a useful biomarker for immediate- and delayed-type reactions, but it has limitations, such as low sensitivity 2.
• The test can help identify the culprit medication, especially when used in conjunction with clinical history and other diagnostic tests 2, 3, 4.
• Skin testing is validated for some drugs, such as penicillin, but not for others, and it may induce adverse events, so it should be performed by experienced personnel in an adequate environment 5.

Induction of Allergic Reaction

• There is a risk of inducing an allergic reaction with skin testing, especially with intradermal tests, which can cause adverse events 5.
• However, the available evidence does not suggest that skin testing can induce a long-term allergy 2, 3, 4, 5, 6.
• The primary goal of skin testing is to diagnose and identify the culprit medication, allowing for the selection of alternative treatments and the prevention of future reactions 2, 3, 6.

Precautions and Considerations

• Skin testing should be performed by experienced personnel in an adequate environment, with access to emergency treatments in case of an adverse reaction 5.
• The test should be used in conjunction with clinical history and other diagnostic tests to improve its accuracy and reproducibility 2, 3, 4.
• Patients with a history of anaphylaxis or recent immunoglobulin E-mediated reaction should be carefully evaluated before undergoing skin testing 2, 6.