drug interactions

I was just wondering if there are any drugs or substances that are dangerous to take or interfere with AAS? I’ve heard that antibiotics won’t allow AAS to work. What about oral anti-fungal(gotten ringworm from mats @ dojo)? This may sound stupid, but what about fiber? I just read somewhere on T-mag not to take a multivitamin with fiber because it binds up some of the vitamins and won’t allow them to be absorbed. Obviously there’s a big difference a multi and AAS, but… Any dangerous combinations besides something that raises BP?