It actually depends on the type of pain killer. Some are non-narcotic, over the counter NSAIDS and they are not addictive. However, they are unhealthy in large doses or with frequent use.
Opioids and Opium derivatives like Morphine, Hydrocodone and Oxycodone are definitely addictive if used for a long period of time on a regular basis.
There are other types of pain killers that double as anti-depressants, like Tramadol and Effexor. They are not opioids.
I have a hub on pills, and a hub on addiction. Please feel free to check out my profile page.
I take pain killers for my fibromyalgia. I try to limit my intake of the drugs and use natural ways to relieve pain. For instance, massage, exercise, meditation, yoga, diet, and laughing (believe it or not) actually help with pain. Also, keeping busy helps to distract from the pain.