Biological medical products (biological response modifiers, biologicals) are substances used to modify the immune response and reduce inflammatory reactions. Biologicals are created by biotechnological processes from living cells or their by-products. Biologicals target factors that initiate or maintain the above reactions (cytokines, neurotransmitters, receptors). The use of all biologicals can be associated with an immediate or delayed hypersensitivity reaction. They increase the risk of infection and may mask symptoms of an infection and prevent the CRP from rising. Live vaccines must not be given concurrently with biologicals. The time interval between the withdrawal of the drug and the administration of the vaccine varies from product to product. Contraindications are specific to each drug group.