The diagnosis of allergic reactions during anesthesia is difficult. For example, cardio-respiratory symptoms may be due to the accompanying pharmacological effects of anesthetics and poor interpretation of the reaction during anesthesia. It is important to distinguish whether a real allergic reaction has occurred. Accidents with anesthetics and muscle relaxants are observed more often than we expect. Proper anaphylaxis rarely occurs during anesthesia (1: 20000). Muscle relaxants are the most common causes, followed by latex, chlorhexidine, antibiotics and opioids. To confirm the diagnosis it is necessary to perform a larger number of blood and skin tests. Targeted diagnostic approach and therapy allow avoiding more difficult events. Anesthesia should be selected for those medications that have been tested. Additionally, patients should be premedicated with antihistaminics and systemic steroids, as the emergence of intolerance is not completely excluded by negative testing. There is no gold standard for testing, even if every method is precisely performed; there are always false positive and false negative results. When anaphylaxis appears, urgent approach is needed to provide the patient with appropriate treatment. It is necessary to act according to the established algorithms and treatment protocols. Many anesthesiologists will not ever see such a reaction, and very few will see more than one during their work life. Awareness of allergy in anesthesia is still insufficient.