Here's an article about the side effects you might encounter from these drugs and how to cope with them. Cancer Doesn't Have to Hurt Report any side effects from opiates to your doctor or nurse. Side effects can be managed. Do not stop taking pain medicines because of untreated side effects. Constipation Most medicines for severe pain, including all opiates, cause constipation.
Opiate analgesics make the gut move slower.
Feces, or BMs, get hard and dry. When starting medicines like morphine, hydromorphone, or fentanyl, you will need medicine to maintain regular bowel movements. If your doctor or nurse does not suggest medicine for your bowels, ask about it. It is very important to tell the doctor or nurse if your bowels have not moved for more than two days. Severe constipation causes pain, nausea, and vomiting and can be dangerous.