In the pharmaceutical sector, container-content interactions refer to the transfer of substances between manufacturing equipment, packaging or medical devices, and the drug. These phenomena include the adsorption of active ingredients or excipients onto container walls, their penetration into the interior of materials or their diffusion into the external environment. In addition, these phenomena include the migration of substances from the container to the drug, or from the external environment to the drug.Such interactions can compromise the quality, efficacy and safety of pharmaceutical products, leading to potentially serious adverse effects for patients, such as changes in therapeutic efficacy or toxic reactions.In this work, we have reported on examples of container-content interactions, specifying the circumstances in which they occur, the methodologies used to study them and their impact on both the drug and the patient.