You mean methadone or crystal meth? I will assume you mean crystal meth. It's hard to say what the signs would be in combining heroin with speed, but you could probably imagine someone doing a speedball (coke and heroin) in which case you get the narcosis associated with heroin, plus the hyper-focus and busy-body tweek of speed. In other words, if you're used to seeing someone on heroin, then you would notice a difference because the person would probably be a lot more active and functional with crystal in their system than they normally might be with just heroin.
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