Background: Breakthrough pain is an exacerbation of pain occurring in patients with chronic pain who receive opioid therapy every day. Breakthrough pain has not been routinely recognized, evaluated and treated. This study aimed to analyze the utilization of opiates analgesics, including dose regimentation, frequency of use, and the actual adverse effects in cancer patients with breakthrough pain.Methods: Data were collected by the retrospective method in the period from January to December 2017.Patients involved received opioids around the clock for treating background pain and rescue medication for treating breakthrough pain. The percentage of the rescue medication dose was calculated based on the total daily opioid dose to treat background pain. Descriptive analysis was used.Results: From 335 visits, there were 334 of patient visit where the patient received immediate-release morphine as a rescue medication with a dose percentage between 6.67-60%, and 1 visit where the patient received codeine with a dose percentage of 16.67%. Of 335 visits, 233 patient visits received the right proportion of opioid rescue medication doses, while 102 patient visits received a greater dose proportion than the recommended dose of 5-20%.Conclusions: Immediate-release morphine is the most commonly prescribed analgesic to treat breakthrough pain and used at 6.67-60% of daily dose with the frequency of use between 2 to 6 times a day. There were 189 (56.42%) patient visits when the patient experienced the adverse effects of the opioid. The identified actual adverse effects are constipation, nausea, and vomiting.