(HealthDay) -- Heroin addicts often have an increased sensitivity to pain, and this sensitivity does not subside over the course of treatment with methadone or other opioids, new research finds.
Researchers from the University of California-Los Angeles sought to determine how increased sensitivity to pain (also called hyperalgesia) might change as a heroin addict moves from drug abuse to stabilization and eventually to maintenance on a pain-treatment opioid such as methadone or buprenorphine.
The investigators assessed the pain responses of 82 heroin addicts who sought treatment and were given either methadone or buprenorphine. The addicts' pain responses were compared to people who didn't use drugs.
Pain responses in both groups were measured using electrical stimulation and the cold pressor test, in which a hand is placed in ice cold water.
The results showed no significant changes in pain response among heroin addicts who took either methadone or buprenorphine for maintenance therapy.
The study appears in The Journal of Pain.
Doctors need to be aware of opioid-induced pain sensitivity associated with addiction in patients prescribed opioids as well as those taking the drugs illegally, according to the study.
Explore further: Harmful patterns of painkiller prescriptions seen among methadone patients
The U.S. National Institute on Drug Abuse has more about treatments for drug addiction.