Background: In the case of refractory diarrhea that cannot be treated with loperamide only, drugs such as octreotide and serotonin receptor antagonists are generally recommended. We have reported a case of refractory diarrhea associated with carcinoid syndrome in which symptoms improved only with opioid switching, without octreotide. Case: We experienced a case of a 28-year-old female with cervical cancer. She was diagnosed with recurrence after cervical cancer surgery and presented with pain and diarrhea. Her diarrhea did not improve sufficiently after taking loperamide. She was admitted to the palliative care hospital for symptom control due to persistent diarrhea and right lower extremity pain associated with bone metastasis. We diagnosed the cause of her diarrhea as carcinoid syndrome by some laboratory examination. For pain management, we switched opioids from transdermal fentanyl to continuous subcutaneous infusion of morphine. It resulted in pain relief and improvement in the frequency of diarrhea, and she was able to be discharged home. Conclusion: In cases of refractory diarrhea and in patients who need opioids, there is one option to use morphine. If it is effective, it may simply resolve both pain and diarrhea and reduce the use of multiple medications.