AIM The goal of this study was to assess the effect of patient information about the analgesics used after breast surgery, on patient's level of pain and mobilisation ability. BACKGROUND Pain needs to be managed efficiently; in particular, for surgical cases, postoperative pain must be effectively controlled. Information about analgesic helped reduce the severity of pain. DESIGN This study was a clinical trial comparing a test group that received information about the analgesic to be used and a control group that received information as usual. METHODS Eighty-four patients who had a modified radical mastectomy or breast-conserving surgery were included in the study. Data were collected in a breast surgery clinic with a questionnaire, with the use of Short-form McGill-Melzack Pain Questionnaire and the Visual Analogue Scale. The test group received information about the surgical pain and the analgesics that would be used during the postoperative period. RESULTS The results showed that the level of pain reported by patients was similar in the test and control groups. However, the average level of postoperative pain in the test group was lower than that in the control group. The total pain reduction score for the test group, after surgery, was greater than for the control group. Following surgery, 73·8% of the test group and 50·0% of the control group achieved mobilisation within the first six hours. CONCLUSION Informing patients about the analgesics to be used for their care reduced pain and provided earlier mobilisation. RELEVANCE TO CLINICAL PRACTICE The findings of this study can provide guidance to nurses and improve analgesic control of pain management.