Methadone is known mainly for treating heroin addictions but it is also prescribed for pain. Health officials say most of the overdose deaths are people who take it for pain - not heroin addicts.
New federal data shows the number and rate of methadone-related deaths have fallen since 2007.
Experts believe doctors are more cautious today about prescribing methadone for pain because of federal warnings and state prescription monitoring programs.
The Centers for Disease Control and Prevention released the study Tuesday.