I have just discovered this post. My husband has advanced bowel cancer and has currently been prescribed fentanyl patches, He gets these patches changed on a weekly basis. He is currently in hospital just now recovering from a sepsis infection. His palliative nurse noticed that when she saw him on the ward that he did not have his patch on from last week and thinks it may have come while going through A & E and moving around different wards. She said they were going to administer the fentanyl through a drip or pump as they were giving him anti-sickness meds intravenously also and he is also still receiving antibiotics. I was unable to get up to the hospital today and phoned him instead and he sounded really tired and groggy. I believe the Fentanyl can cause the person to feel really tired and sleepy and he was able to tell me he slept most of the day away. Is it possible this has been due to getting the Fentanyl intravenously or could it be a combination of that the antibiotics and anti-sickness meds. Thanks.