In the UK, persons who are prescribed oral methadone can continue to drive after they have satisfactorily completed an independent medical examination which will include a urine screen for drugs. The license will be issued for 12 months at a time and even then, only following a favourable assessment from their own doctor. Individuals who are prescribed methadone for either IV or IM administration cannot drive in the UK, mainly due to the increased sedation effects that this route of use can cause. Mortality
In the United States, deaths linked to methadone more than quadrupled in the five-year period between 1999 and 2004. According to the U.S. National Center for Health Statistics, as well as a 2006 series in the Charleston Gazette (West Virginia), medical examiners listed methadone as contributing to 3,849 deaths in 2004. That number was up from 790 in 1999. Approximately 82 percent of those deaths were listed as accidental, and most deaths involved combinations of methadone with other drugs (especially benzodiazepines). Although deaths from methadone are on the rise, methadone-associated deaths are not being caused primarily by methadone intended for methadone treatment programs, according to a panel of experts convened by the Substance Abuse and Mental Health Services Administration, which released a report titled "Methadone-Associated Mortality, Report of a National Assessment". The consensus report concludes that "although the data remains incomplete, National Assessment meeting participants concurred that methadone tablets or Diskets® distributed through channels other than opioid treatment programs most likely are the central factors in methadone-associated mortality.
Black box warning
Methadone has the following US FDA black box warning:
Risk of addiction and abuse
Potentially fatal respiratory depression
Lethal overdose in accidental ingestion
QT prolongation
Neonatal opioid withdrawal syndrome in children of pregnant women
CYP450 drug interactions
Risks when used with benzodiazepines and other CNS depressants, including alcohol. A certified opioid treatment program is required under federal law (42 CFR 8.12) when dispensing methadone for the treatment of opioid addiction or detoxification. Overdose
Most people who overdose on methadone show some of the following symptoms:

Miosis (constricted pupils)
Vomiting
Spasms of the stomach and intestines
Hypoventilation (breathing that is too slow/shallow)
Drowsiness, sleepiness, disorientation, sedation, unresponsiveness
Skin that is cool, clammy (damp), and pale
Blue fingernails and lips
Limp muscles, trouble staying awake, nausea
Unconsciousness and comaThe respiratory depression of an overdose can be treated with naloxone. Naloxone is preferred to the newer, longer-acting antagonist naltrexone. Despite methadones much longer duration of action compared to either heroin and other shorter-acting agonists and the need for repeat doses of the antagonist naloxone, it is still used for overdose therapy. As naltrexone has a longer half-life, it is more difficult to titrate. If too large a dose of the opioid antagonist is given to a dependent person, it will result in withdrawal symptoms (possibly severe). When using naloxone, the naloxone will be quickly eliminated and the withdrawal will be short-lived. Doses of naltrexone take longer to be eliminated from the persons system.