The main objective of this study is to compare pholcodine exposure in patients having presented with a perianaesthetic anaphylactic reaction to a NMBA (cases) to pholcodine exposure in matched anaesthetised patients with injection of NMBA, who did not present with an anaphylactic reaction (controls).

The secondary objectives of the study are:

• To compare anti-pholcodine IgE, anti-ammonium IV IgE and total IgE levels between the case and control groups.
• To study the concordance between exposure to pholcodine in cases and controls, by means of a patient self-questionnaire on the one hand and, on the other hand, by a computerized drug history, supplemented where relevant by the drug master file.
• To study the impact of taking 1, 2 or 3 sources in account for pholcodine exposition.
• To study the association between exposure to pholcodine and the presence/levels of pholcodine-specific IgE, reflecting sensitisation to pholcodine.
• To study NMBA and pholcodine cross-sensitisation by testing skin reactions to pholcodine in case patients allergic to (at least) one NMBA.

Inclusion Criteria:

• Male or female, age ≥ 2 years old.
• Referred to anaesthesia-allergy consultation within (approximately) 6 to 12 weeks of occurrence of peranaesthetic anaphylactic reaction during anaesthesia with administration of NMBAs (only for case patient).
• Having given his/her consent (or the 2 parents consent for minors).
• Affiliated with a social security scheme or dependent.
• Able to answer a medicinal product intake questionnaire
• In a clinical condition compatible with skin tests (no skin disease or psychiatric illness, etc.) (only for case patient)
• Having stopped any anti-histamine treatment at least 8 days previously (only for case patient).
• With positive skin test for the suspected NMBA (ony for case patient).
• Patient anaesthetised in a control recruitment centre (only for control patients)
• Having undergone anaesthesia with NMBA injection, without onset of peranaesthetic anaphylactic reaction whatever his medical history (only for control patients)

Exclusion Criteria:

• Patients who have refused, or are unable to give their consent
• Patients who have had negative control skin tests
• Anaphylaxis suspected to be related to other drugs given on induction of anaesthesia, eg. antibiotics
• Having presented with anaphylactic reaction during a previous anaesthesia without NMBA injection
• Pregnant females at inclusion or during 12 months before anaesthesia