Cons:

Methadone use has a number of side-effects such as constipation, sweating, loss of libido, sleep disturbance, weight gain, dental problems, vomiting, and serious bowel problems. While most of the side-effects are reduced or managed by controlled prescription, they can occasionally be severe enough to affect a person's health sufficiently for him to discontinue treatment (Withers, 1999)

One of the 'advantages' of methadone, i.e., it blocks the euphoric high of heroin can also become a disadvantage at times, as many addicts under methadone treatment miss the 'high' of heroin and could overdose themselves for the sake of experiencing the euphoria.

Methadone is a long-acting opioid. In other words, its effect in the body remains for up to 36 hours. This makes it difficult for patients under methadone treatment, desirous of becoming completely drug-free, to kick their methadone habit. According to some, it is far more difficult to kick the methadone...
[ View Full Essay]