Please do not start an addiction to H, it is scary shit and when you get off of it you will never forget being high and how bad you want to be.
However, you should be fine.
-420
Hey dood, I know you're relatively new and more importantly, that you're heart is in the right place here, but please refrain from posting in Harm Reduction threads if your only purpose is to tell the OP not to use the drugs in the first place. We can assume with a high degree of certainty that these people are already aware that these drugs are addictive and it has, in the past, detracted from and destroyed threads. Again, I know you're heart is in the right place, but this addition is erroneous at this point.
Now, onto OP. There seems to be a small amount of conjecture regarding THC et al's propensity for inducing respiratory depression, but the overwhelming point I draw from the research is that, yes, it indeed can contribute to respiratory depression. Now, to what degree, I am unsure. This is my own opinion for the most part, but I'm willing to bet that Cannabis is not especially dangerous when combined with other central nervous system depressants. I've never read an article that states Cannabis intoxication as a primary, contributing factor in a lethal overdose.
I think we can leave this as, "yes, it probably does, but not to a degree that anyone should be especially worried about", unlike say, Alcohol, Benzodiazepines or Barbiturates.