Technically you can take them together, however, this is extremely dangerous. Although injury's or death are not common on low dosages of Methadone and use of Oxycontin, i would not recommend it....
It is suggested that no nerve pills be taken along with Methdone. A toxic reaction can occur and usually death follows. Especially Xanax and Klonipin the main culprit. Many have died, even on the...
Methadone usually takes about an hour to fully feel the effects. If you're going through withdrawal, you may start to feel relief within about 30-40 minutes or so.