Phadia C1 and C2 tests are used to detect blood levels of the IgE (antibodies) responsible for allergic reactions to various penicillin compounds (penicillin G, penicillin V, amoxicillin, etc.) and sometimes cephalosporins. Although 10% of the population claims to be allergic to penicillin, real allergies are rare and occur in less than 1% of the population. This difference is due to the fact that most penicillin allergies have never been confirmed (confusion between the symptoms of infection and symptoms due to medication) or have disappeared over time. Since penicillins are the best choice for the treatment of common bacterial infections, it is relevant to confirm a real allergy to penicillins and related antibiotics. The interpretation chart accompanying the results expresses the probability of an allergic reaction to penicillins, but not necessarily the severity of the reaction. Case history and clinical examination by the physician are essential for a reliable interpretation of results.
An anti-penicillin V or G IgE result below 0.35 kilounits per litre (< 0.35 kU/L) indicates that there is less than a 5% probability that the individual is allergic to penicillins, but it DOES NOT COMPLETELY RULE OUT THIS POSSIBILITY. Any result above 0.35 kU/L should be considered positive.