info i found-

[Before using methadone
Taking methadone improperly will increase your risk of serious side effects or death. Even if you have used other narcotic medications, you may still have serious side effects from methadone. Follow all dosing instructions carefully. Methadone may be habit-forming and should be used only by the person it was prescribed for. Methadone should never be given to another person, especially someone who has a history of drug abuse or addiction. Keep the medication in a secure place where others cannot get to it. Do not use this medication if you have ever had an allergic reaction to a narcotic medicine (examples include codeine, morphine, Oxycontin, Darvocet, Percocet, Vicodin, Lortab, and many others). You should also not take methadone if you are having an asthma attack or if you have a bowel obstruction called paralytic ileus.

Before taking methadone, talk to your doctor if you have:

*
a personal or family history of "Long QT syndrome";
*
asthma, COPD, sleep apnea, or other breathing disorders;
* liver or kidney disease;
*
underactive thyroid;
*
curvature of the spine;
*
a history of head injury or brain tumor;
*
epilepsy or other seizure disorder;
*
low blood pressure;
*
gallbladder disease;
*
Addison's disease or other adrenal gland disorders;
*
enlarged prostate, urination problems;
*
mental illness; or
*
a history of drug or alcohol addiction.]
more -
http://www.drugs.com/methadone.html
http://www.rxlist.com/dolophine-drug.htm
http://www.medicinenet.com/methadone...et/article.htm