Objectives: The objectives of this study were to examine the main reasons for referring patients to a clinical pharmacologist to assess whether there are contraindications to vaccination against COVID-19, which referral diagnoses were assessed as potential contraindications, to examine the relationship between the clinical pharmacologist's recommendations and the collected characteristics of the patients, to examine which vaccines are safer for people with certain comorbidities, and to examine the demographic characteristics of the patients. Study Design: This is a cross-sectional study with historical data. Material and Methods: The study was conducted on 137 patients referred for the purpose of assessing whether there are contraindications to vaccination against COVID-19. The following characteristics were collected from the Hospital Information System: age, sex, referral diagnosis, comorbidities, hypersensitivity to other allergens, medications used by the patient, and the vaccination status before and after the examination. Results: The study included 108 (78.8%) women and 29 (21.2%) men. The most common referral diagnoses were the following: suspected side effects of previously received vaccine against COVID-19, hypersensitivity to other allergens, and coagulation disorders. The results indicate a connection between the recommendations of the clinical pharmacologist and the suspected side effects as the referral diagnosis, hypersensitivity to other vaccines and sex. The patients with certain comorbidities were recommended mRNA and protein vaccines. Conclusion: Based on the results of the research, it can be concluded that the majority of the patients with a contraindication to vaccination developed a side effect to a previously received dose of this vaccine. Other common referral diagnoses are not a contraindication. The share of younger and older patients is equal, and most of them are women. The patients with atopic diathesis and thrombophilia were recommended mRNA or protein vaccines. There is a relation between the recommended testing for vaccine excipients and hypersensitivity to other vaccines.