Placebo controlled drug provocation testing (PCDPT) in drug allergy diagnostics: The most common drugs in allergological diagnostics and the most common reactions. G. Balakirski1, G. Wurpts1, H. F. Merk1   1Department of Dermatology and Allergology, University Hospital of Aachen, Germany Background The current guidelines on diagnostics of drug allergy classify the PCDPT as a gold standard if other diagnostic procedures such as in vivo skin testing and in vitro laboratory tests do not lead to conclusive results. We analyzed all the PCDPTs performed in our department in the last 5 years with the question what drugs we tested and what reactions our patients showed. Methods All the patients underwent PCDPTs from the 1st of October 2008 to the 1st of October 2013 in our department were analyzed for the type of drugs tested and reaction the patients showed.  All the patients reported about one or more events with a drug reaction in the background and underwent standard diagnostic procedures prior PCDPT. Results The PCDPTs were performed either to confirm (26% of cases) or to deny (32% of cases) the diagnosis of drug allergy or to find an alternative drug if the allergy to certain drugs was confirmed by prior diagnostics (42% of cases). PCDPTs were performed in 243 patients: 22% were to aspirin, 11% to paracetamol and other NSAIDs, 10% to selective COX-2 inhibitors, 4% to other non-NSAID analgesics ,18% to local anesthetics, 17% to antibiotics, 8% to steroids and 10% to other drugs (Fig. 1). Fig. 1: Drugs sorted by class that placebo controlled drug provocation testing was performed with. In 81% of cases no reaction to both placebo and the drug was seen. 8% of PCDPTs showed objectified reaction to the drug, 4% a non-objectifiable reaction to the drug, 5% a questionable reaction to the drug and in 2% of cases a non-objectifiable reaction to placebo but no reaction to drug was seen (Fig. 2). Fig. 2: The reactions to placebo controlled drug provocation testing we have observed in our patients. 66% of the reactions to placebo and 40% of the questionable responses to the drug occurred in PCDPT to local anesthetic . 50% of the objectified responses to the drug occurred in PCDPT to aspirin (Fig. 3). Fig. 3: Drugs objectified responses to occurred in placebo controlled drug provocation testing Conclusion Aspirin is the most common drug we tested and the most common drug caused the objectified reaction during PCDPTs.  In the most cases reaction to placebo and questionable responses to the drug occurred in PCDPT to local anesthetic.  In most of cases no reaction to both placebo and the drug tested was seen. Contact information: Galina Balakirski, gbalakirski@ukaachen.de