Fentanyl My aunt was just put on a new pain medication for the cancer that is spreading through her body, including her throat, lungs, and back. Fentanyl is an extremely potent synthetic pain medication similar to morphine. The side effects listed are many and varied. The most common is respiratory depression, slow heart rate and low pressure. Nausea and vomiting can occur but these seem to be less a problem than with other pain medications.
Constipation can be a problem as fentanyl slows down the motility of the intestine.
Skin itching is also a side effect. Other less common side effects include urine retention, headache, dizziness, nervousness, hallucinations, anxiety, depression, drowsiness, loss of appetite and confusion. Many pain medications list these side effects. However, keep in mind with cancer spreading through her body, you should not worry about addiction and dependency. Report any new symptoms to her doctor because he or she will be better able to determine if it is the medication or the disease process causing your aunt's problems.