OBJECTIVES: As different inhalation devices require largely different techniques of use, the non-trained switch of device in chronic obstructive pulmonary disease (COPD) and asthma patients may be associated with a poor inhalation technique and, consequently, in a reduction of adherence and worsening in pathology control. Aim of this analysis is to estimate the possible economic impact on Italian National Health Service (INHS) related to errors in inhalation in patients switching device without adequate training.  METHODS: An Italian observational study on patients with COPD and asthma, highlights higher healthcare resource consumption associated with inhaler mishandling. Particularly, significantly higher rates of hospitalizations, emergency room (ER) access and pharmacological treatment (steroids and antimicrobials) were observed. These differences in resource consumption were monetized from the INHS perspective considering national DRGs tariffs for hospitalizations and ER access and public price for drugs consumption. RESULTS: Comparing a population of 100 COPD patients with at least a critical error in inhalation with 100 COPD patients without errors in inhalation, the first population is associated with an excess of 11.5 hospitalizations, 13 ER access, 19.5 antimicrobial courses and 47 corticosteroids courses. In the same way, if we compare 100 asthma patients with at least a critical error in inhalation with 100 asthma patients without errors in inhalation, the first population is associated with an excess of 19 hospitalizations, 26.5 ER access, 4.5 antimicrobial courses and 21.5 corticosteroids courses. These differences in resource consumption are associated with an yearly incremental cost for 100 patients, due to inhalation errors, of 23,444€ in COPD patients and 44,104€ in asthma. CONCLUSIONS: This evaluation shows that misuse of inhalation devices, possibly associated to inadequate training or non-consented switch of inhaled medications, is associated with a decrease in disease control and an increase in healthcare resource consumption and costs in COPD and asthma patients.