Guideline for allergological diagnosis of drug hypersensitivity reactions: S2k Guideline of the German Society for Allergology and Clinical Immunology (DGAKI) in cooperation with the German Dermatological Society (DDG), the Association of German Allergologists (ÄDA), the German Society for Pediatric Allergology (GPA), the German Contact Dermatitis Research Group (DKG), the German Society for Pneumology (DGP), the German Society of Otorhinolaryngology, Head and Neck Surgery, the Austrian Society of Allergology and Immunology (ÖGAI), the Austrian Society of Dermatology and Venereology (ÖGDV), the German Academy of Allergology and Environmental Medicine (DAAU), and the German Documentation Center for Severe Skin Reactions (dZh).

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Déclaration de conflit d'intérêts

The information on interests was collected using the AWMF form of 2018 and assessed by Prof. Dr. Monika Raulf for a thematic relation to the guideline. Guideline-relevant lecturing or consulting activities for manufacturers of devices for allergy diagnosis were categorized as a low conflict of interest, and direct financial secondary interests (e.g., share ownership, patent) as a moderate/high conflict of interest. Low conflicts of interest resulted in abstention from voting. Strong conflicts of interest were not present. Protective factors counteracting conflict of interest bias were the pluralistic composition of the guideline group, structured consensus building under neutral moderation, discussion on interests, and handling of conflicts of interest at the beginning of each consensus meeting, and a public consultation version. Abbreviations.Abbreviations. ADRAdverse drug reactionAGEPAcute generalized exanthematous pustulosisAWMFGerman Association of the Scientific Medical SocietiesCOPDChronic obstructive pulmonary diseaseDGAKIGerman Society for Allergology and Clinical ImmunologyDRESSDrug reaction with eosinophilia and systemic symptomsINNInternational non-proprietary nameMPEMaculopapular exanthemNSAIDNon-steroidal anti-inflammatory drugsSJSStevens-Johnson syndromeTENToxic epidermal necrolysis Table 1.Definitions.Adverse drug reaction (ADR): A noxious and unintended reaction that occurs in addition to the intended effect of a drug, for which a causal relationship between the use of the drug and the adverse effect is suspected. ADRs can be both type A (pharmacological/toxic) and type B (hypersensitivity).Type A (“augmented” = pharmacological/toxic (on-target) drug effects): Disease manifestations due to dose-dependent predictable pharmacological/toxic effects of a drug at the recommended dose (examples: sedative effect of older antihistamines, hair loss due to cytostatics) or increased dosage (intoxication).Type B (“bizarre” = hypersensitivity (off-target) reactions): Individual, unpredictable clinical reaction to a drug, i.e., symptoms occur only in specially predisposed patients. Two forms can be distinguished:   –Drug allergy: Hypersensitivity is based on an immunological reaction (types I – IV according to Coombs and Gell).   –Non-allergic drug hypersensitivity: An allergic mechanism is not detectable. Previously, this type of reaction was further divided into:      –Drug intolerance: Typical symptoms of pharmacological action (toxicity) develop even at low doses that are usually tolerated.      –Drug idiosyncrasy: The symptoms differ from the pharmacological substance effect. In cases where the symptomatology of this form of hypersensitivity looked similar to an allergic reaction, the term pseudoallergy has also been used. Table 2.Time interval, clinic, and pathomechanism – three levels for classifying a drug hypersensitivity reaction. 1) Time reaction intervalsa) For those already sensitized   –Immediate reaction (“immediate”) immediate up to 60 minutes (in rare exceptions up to 6 hours)   –Delayed reaction (“non-immediate”) > 6 hours to several weeksb) In case of new sensitization under therapy   –Typical sensitization latency 7 – 10 days2) Clinical manifestationsa) Immediate reaction: E.g., flush, urticaria, angioedema, bronchospasm, anaphylaxis.b) Late reaction: Maculopapular exanthem (MPE), acute generalized exanthematous pustulosis (AGEP). Severe cutaneous drug reactions: Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), drug reaction with eosinophilia and systemic symptoms (DRESS).c) Others: E.g., hepatitis, cytopenia, autoimmune diseases (e.g., lupus erythematosus, drug-induced linear IgA dermatosis)3) Pathomechanisma) Allergic hypersensitivity: Immediate type (type I according to Coombs and Gell, IgE mediated): typical manifestation, immediate-type symptoms (reaction time: 0 – 6 hours)b) Non-allergic hypersensitivity: Typical manifestation immediate-type symptoms (reaction time: 0 – 6 hours, rarely up to 12 hours)c) Allergic hypersensitivity: Delayed-type (type IV according to Coombs and Gell, T-cell mediated): typical manifestation delayed-type (reaction time: 24 – 72 hours, begin rarely after 6 – 24 hours).d) Other forms of immunologically mediated hypersensitivity (type II, type III according to Coombs and Gell, IgG, IgA, or IgM mediated): Cytopenias, serum sickness, immune complex vasculitis (vasculitis allergica); (reaction time: 24 hours or more).e) In case of new sensitization under therapy: Typical immunologic sensitization latency 5 – 7 days for types I –IV, with reaction latency of 1 –3 days). Onset of MPE after 7 –10 days. However, the reaction in SJS/TEN, DRESS may occur after weeks, that in autoimmune diseases (e.g., lupus erythematosus) after months, probably due to sensitization only after prolonged exposure (e.g., sensitization or triggering favored by cofactors). Table 3.Typical time interval between start of drug intake and first occurrence of reactions. Reaction patternTime intervalUrticaria, asthma, anaphylaxis≤ 1 hour, rarely up to 6 hours after start of exposureFixed drug exanthem ≤ 48 hours, rarely later after start of exposureMaculopapular drug exanthem4 – 14 days after start of exposure*AGEP1 –12 days after start of exposure**SJS/TEN4 – 28 days after start of exposure***DRESS2 – 8 weeks after start of exposureAGEP = acute exanthematous generalized pustulosis; SJS = Stevens-Johnson Syndrome; TEN = toxic epidermal necrolysis; DRESS = drug reaction with eosinophilia and systemic symptoms. *In repeat reactions, time interval typically shortened compared to initial reaction. In maculopapular drug exanthem typically reaction after 1 – 4 days, in AGEP, SJS, TEN, DRESS typical time interval after repeat reactions not studied. **For antibiotics mostly 1 – 2 days, for other drugs often 7 – 12 days. ***Sometimes longer for allopurinol. Table 4.Important clinical and anamnestic information for the test plan. A) Clinical manifestation   – Documentation of clinical manifestations and/or organ systems involved: e.g., skin, airways, cardiovascular system, gastrointestinal tract, liver, kidney.   – Exact description of the clinical-morphological findings (especially in case of skin manifestations/mucosal reactions) additionally photo documentation   – General symptoms: Fever, reduced general condition   – Course of the reaction (onset of the reaction in temporal relation to the drug administration, duration of the reaction, morphological change of the reaction).   – Laboratory findings (e.g., blood count changes such as eosinophilia, thrombocytopenia; liver and kidney values; serum tryptase).   – If necessary, histological findings (especially in the case of blistering skin reactions)B) Other circumstances of the reaction   – Acute illness at the time of the reaction (e.g., concurrent infectious disease).   – Co-factors that may lower the threshold for an allergic or non-allergic reaction: stress, physical exertion, food intake, alcohol intake, UV exposure, menstruation.C) Documentation of drugs used in temporal relation to the reaction.   – Indication for drug use   – Trade name   – Mode of application   – Ingredients (active ingredients)   – Duration of application   – Dosage   – Tolerance after previous or during renewed applicationD) General history and findings   – Known hypersensitivity reactions (allergy passport)   – Similar reactions without drug application (e.g., natural latex allergy)   – Atopic diseases, food allergy   – Disposing diseases (e.g., asthma, nasal polyps, chronic urticaria, mastocytosis, infections, e.g., HIV, EBV)   – Other relevant past or current medical conditions (including somatoform or mental health conditions)   – Noxious agents: Nicotine, alcohol, drugs   – Current medication (long-term medication)E) Chronology of the hypersensitivity reaction   – Timing in relation to drug application   – First occurrence   – Course and resolution   – Therapeutic measures and responseF) Diagnosis and pathophysiological classification of the clinical reaction taking into account (see Table 1):   – Morphology and symptoms   – Time courseNote: In the case of multiple reactions, the information for each individual reaction is required. Table 5.Non-irritant skin test concentrations of commonly tested drugs [17]. Drug or classSkin prick testIntradermal test8Patch testBeta-lactam antibiotics   Benzylpenicilloyl-octa-L-lysine8.6 × 10-5 mol/L8.6 × 10-5 mol/LNA   Sodium benzylpenilloate1.5 × 10-3 mol/L1.5 × 10-3 mol/LNA   Benzylpenicillin10,000 UI/mL10,000 UI/mL5%   Amoxicillin20 mg/mL20 mg/mL5%   Ampicillin20 mg/mL20 mg/mL5%   Cephalosporins20 mg/mL1020 mg/mL105%Anticoagulants   Heparins1Undiluted81/10 dilutedUndiluted8   Heparinoids2Undiluted81/10 dilutedUndiluted8Platinum salts   Carboplatin10 mg/mL1 mg/mLNA   Oxaliplatin1 mg/mL0.1 mg/mLNA   Cisplatin1 mg/mL0.1 mg/mLNANSAID   Pyrazolone3Suspension90.1 – 1 mg/mL10%   Coxibe4Suspension910%   Other NSAIDs5Suspension90.1 – 1 mg/mL10%Biologics   Adalimumab50 mg/mL50 mg/mLUndiluted8   Etanercept25 mg/mL5 mg/mLNA   Infliximab10 mg/mL10 mg/mLNA   Omalizumab1.25 µg/mL1.25 µg/mLNAOther   Local anestheticsUndiluted81/10 dilutedUndiluted8   X-ray contrast agentUndiluted81/10 dilutedUndiluted8   Gadolinium chelatesUndiluted81/10 dilutedNA   Patent blueUndiluted1/10 dilutedNA   Methylene blueUndiluted1/100 dilutedNA   FluoresceinUndiluted81/10 dilutedUndiluted8   Proton pump inhibitors6Undiluted940 mg/mL10%   Anticonvulsants7NANA10%   Chlorhexidine digluconate5 mg/mL0.002 mg/mL1% 1Heparins: unfractionated heparin, nadroparin, dalteparin, enoxaparin; testing contraindicated in heparin-induced thrombocytopenia. 2Heparinoids: danaparoid, fondaparinux. 3Pyrazolones: metamizole, propyphenazone, aminopyrine, phenazone, phenylbutazone. 4Coxibs: celecoxib, etoricoxib, valdecoxib. 5Other nonsteroidal anti-inflammatory drugs: e.g., aspirin, ibuprofen, naproxen, indomethacin, diclofenac, fenoprofen, meloxicam, mefenamic acid, nimesulide. 6For lasoprazole and rabeprazole no intravenous solution for intradermal test (IDT), only skin prick test. 7For severe reactions, first test with 1%. 8Use of commercially available solution for intravenous infusion or subcutaneous injection. 9Crushing of the tablet and preparation of a suspension with physiological saline solution. 10Only for cefepime 2 mg/mL each. NA = not applicable or no concentration recommended. Table 6.Selection of commercial tests for the determination of specific IgE antibodies against drugs in serum*. – Ampicilloyl1– Amoxicylloyl1– Cefaclor2– Chlorhexidine2– Gelatin (bovine)1 Galactoseα−1,3-galactose (α-gal)1,3– Insulin (Human) 1– Morphine2– Penicilloyl G1– Penicilloyl V1– Pholcodin2– Suxamethonium (succinylcholine) 2*When determining sIgE for drugs, attention must be paid to the validation of the test methods. CE certification requires at least five, FDA registration at least 30 positive patient sera, as well as studies on stability and reproducibility. If these criteria are not met, test reagents may be offered for research purposes. Here, particular attention should be paid to the quality of the deposited literature. In routine diagnostics, no determinations of sIgE should be performed against substances for which no IgE-mediated allergic reactions have been described so far. 1CE-certified and FDA-registered; 2CE-certified,3 α-gal, this is an IgE-reactive sugar epitope which is held responsible for anaphylactic reactions to cetuximab and infusion solutions containing gelatine. Figure 1.Diagnostic algorithm for suspected drug hypersensitivity [2].