The chapter on polypharmacy in the medically ill strays from the topic of psychiatric polypharmacy and provides a more general overview of drug-drug interactions. The numerous tables address selected interactions between psychiatric and other medical drugs, but they are incomplete and not derived from original data but, rather, adapted from earlier (1995, 2000) publications. Under such circumstances, it is always difficult to know if fact, fiction, or combinations thereof are being passed on to current readers. Perhaps even more troublesome are unsubstantiated, unreferenced statements (e.g., blood-brain barrier changes with age allow adequate CSF lithium levels to be attained at lower serum levels). The chapter on PTSD has a considerable amount on neurochemistry, perhaps because, as the authors point out, "there have been no clinical studies of polypharmacy in PTSD."