Aim Wrong use of an inhaler arising from a lack of knowledge can negatively affect treatment management. Therefore, this study was performed with the aim of determining the effects on treatment management of inhaler training carried out under the leadership of a nurse in individuals with medium and advanced stage chronic obstructive pulmonary disease (COPD). Methods This was an experimentally designed pre-test post-test study with a control group. Participants were interviewed four times in 1 year. The experimental group performed inhaler training. A Patient Description and Follow-Up Form, an Inhaler Drug Use Skill Chart, the Morisky eight-item Medication Adherence Scale, the COPD Assessment Test, and the St. George Respiration Questionnaire were used to collect data. Data analysis was performed by SPSS, using nonparametric tests. Results Although there was no significant difference between the groups, a reduction in hospital visits and admissions because of attacks was seen in the experimental group (p= .239,p= .492). It was found there was a greater increase in the correct use of the inhaler in the experimental group than in the control group, and that correct use of the handihaler increased significantly (p= .008). Also, the increases in adherence to treatment (p= .006) and quality of life (p= .010) in the experimental group were significantly different from the control group. In the control group, the annual decline in forced expiratory volume in 1 s increased significantly (p= .016). Conclusions It was seen that long-term inhaler training given by nurses at regular intervals made a significant contribution to treatment management.