Balance is the watchword of health. Since drugs by definition unbalance our systems, they are to be avoided if at all possible. “Differential Medicine” (Maximum Irony, http://www.amazon.com/Maximum-Irony-Mark-L-Collins/dp/1419697013) is the antidote to this.
A recent study reiterates this point by showing how a normally harmless gut bacterium can “go wild” when the flora are disturbed (unbalanced) by antibiotics.
Hoshi N, Medzhitov R. Germs gone wild. Nat Med. 2012 May 4;18(5):654-6. doi: 10.1038/nm.2767. PubMed PMID: 22561817.