Well, it depends on what drugs you're talking about, of course. If you're talking about cardiovascular drugs, renal drugs, or gastrointestinal drugs, I'm not sure you can demonstrate that they would have much effect on function. But if you're talking about nervous system drugs, yes, and one of the risks is certainly, in contemporary medicine, the risk of overdose; that is, of combined use of large numbers of drugs without adequate thought as to what the combined effects may be.
On May 1st, 2014. See this statement in context.