Join Date: Sep 2009
Location: Greater Toronto Area
There's not a whole lot of merit to the idea that it's harder on the hard because they're "opposing" forces or whatever lol. It's not like the heart is trying to beat at two speeds at once listening to the drugs separately.
I think the misconception largely comes from the notorious danger of a "speedball", a recreational mixture of heroin and cocaine. What happens is that an upper and a downer mixed like this can make it FEEL like you're taking less of both, so people end up taking more, and since cocaine has a MUCH shorter duration, when it starts wearing off, there's nothing keeping heroin's respiratory depression counteracted and you start overdosing on the heroin. So if you were sticking to a certain dose in the first place, it's conceivable that the mixture could actually be even a bit safer, but it's dangerous because people DON'T.
Either way, at therapeutic doses, you're not taking anything near the level of an overdose. You'll be fine, and yes, it's pretty common.