Side effects: Regular use of opioids almost always causes side effects, especially constipation. Your health care provider can help you prevent or control side effects so you can continue taking your medication. If you become overly sleepy, you or your family should contact your provider right away. Nausea and vomiting can occur after starting opioids, but these side effects tend to go away after a few days. If you have itching or a rash, it may be the sign of an allergic reaction to opioids. Tell your provider and he or she can change your medication. If pain increases over time, a higher dose of opioid medication may be needed. Most people build up a tolerance to the side effects of these drugs, so they can handle the side effects of increased doses more easily.
Source: Susan G. Komen 2019