A friend of mine got hooked on heroin and ended up on methadone maintence. He’s since managed to get off that and is clean, but he had horror stories of people on methadone abusing benzodiazepines like crazy. Apparently mixing methadone and high doses of drugs like Xanax produce effects similar to heroin, but benzos are really hard to get off. He talked about a woman who couldn’t get her Xanax fix, and she started having seizures. Benzodiazepines take months to titrate off safely, and higher doses associated with abuse do unpleasant things to your seizure threshold and memory.
Bad stuff unless you must have it.