http://www.nursing.uiowa.edu/sites/adultpain/MedGen/CEILINnt.htm
Pain relief is important so you can live a full and complete life. If you have pain that you can’t get rid of, ask your doctor or nurse for help.
Pain medications are either non-opioids or opioids. Opioids are medications for severe pain and can help relieve symptoms so you can live without pain. When you have severe, long-term pain, it is very rare for you to become "addicted" to your pain medication. Non-opioids are both prescription and non-prescription (depending on dosage) medications such as non-steroidal anti-inflammatory drugs (NSAID’s), aspirin, acetaminophen, ibuprofen, and naproxen.
Non-opioids, like the NSAID’s, have a ceiling effect meaning that there is just so much of the medication that you can take. Taking more of the medicine won’t help you feel any better than taking the recommended dose. If one kind of non-opioid doesn’t work for you, the doctor may tell you to try another one, but they won’t increase your dosage. Don’t take more of the medicine than the doctor prescribes.
Opioids, such as Morphine, Codeine, Fentanyl, Dilaudid, Demerol, Darvon, Lortab, Vicodin, and Methadone, do not have a ceiling effect. If you have severe pain and are taking an opioid, you might become tolerant to it, and the doctor might tell you to increase the dosage to keep your pain under control. Tolerance is not narcotic abuse or addiction, it is simply your body’s adaptation to the pain medication. An increase in the dosage will again manage the pain. Please do not increase the dosage yourself, though, as the doctor will want to "titrate" it carefully, meaning, the medicine will be increased very slowly to find just the right dose to keep your pain under control.
If your doctor has told you to take a certain medication for your pain, be sure to take the medicine on schedule, and let the doctor know if it helps you feel better or not. This will help the doctor or nurse know if you need a change in your medicine or a change in the dosage. Your health care providers want to help you feel better, and will work hard to find a medicine that works well for you.