I definitely sweated a lot on methadone the only time I can remember
Not sweating to badly was when I tried a vegan diet very low fat not the plastic vegan food you can buy but rice and vegetables beans fruit that sort of thing and drinking lots of water .
I was a keen runner at the time and before the diet my sweet used to feel really thick and sticky .
I no longer take methadone and the problems gone away I still don't eat much meat but do eat a little...