Modified-release opioid tablets were introduced into surgical practice in the belief that they provided superior pain relief and reduced nursing workload, and they rapidly became embedded into many perioperative pathways. Although national and international guidelines for the management of postoperative pain now advise against the use of modified-release opioids, they continue to be prescribed in many centres. Recognition that modified-release opioids show lack of benefit and increased risk of harm compared with immediate-release opioids in the acute, postoperative setting has become clear. Their slow onset and offset make rapid and safe titration of these opioids impossible, including down-titration as the patient recovers; pain relief may be less effective; they have been associated with an increased incidence of opioid-related adverse drug events, increased length of hospital stay, and higher readmission rates; and they lead to higher rates of opioid-induced ventilatory impairment and persistent postoperative opioid use. Evidence indicates that modified-release opioids should not be used routinely in the postoperative period.