Home care grows in conjunction with the phenomenon of polypharmacy (synonymous with polymedication) while emerging in parallel with aging and frailty as a real health issue added to comorbidities. It is a situation of drug use for which we do not have an agreed definition. Some authors define polypharmacy as the concomitant ingestion of four or more drugs in the last three months, while other authors raise the number to five different drugs. Polypharmacy is often the result of the sum of appropriate prescriptions of drugs of proven effectiveness in patients with various chronic conditions. In these cases, from the point of view of compliance with clinical practice guidelines, everything would be in order. However, the reality of this situation is far more complex due to the lack of knowledge of the interactions that more than two drugs can cause in patients, in terms of kinetics or dynamics of the active principles, as well as the potentiation of their adverse effects.