A herb is a pharmaceutical in spite of it being called a herb, as Cam states. The dichotomy that many feel they need to emphasis between 'them and us' or 'allopathic and TCM' or 'drugs and herbs' is rather misplaced. Frankly, a herb that causes a rash is no different to a pharmaceutical that causes a rash - it is an allergic reaction; the TCM practitioner misdiagnosed and hence incorrect herbs; or the herbs were contaminated. Herbs are still foreign agents in the body and can disrupt the Yin/Yang balance (or homeostasis) just like pharmaceuticals. Rather, it is the underlying diagnostic model that differentiates these two systems. In TCM, the diagnostic system arguably does better justice to sub-classify an individual's illness and hence more appropriate selection of herbs/drugs.
Regarding MIMS and cross-interaction of herbs with pharmaceuticals or contraindications for herbs, there are two other sources of information that are useful. The Journal of Complementary Medicine regularly mentions updates on these issues with a listing suspect herbs/drugs and evidence or reports to support the warnings. MIMS also publishes a separate publication with all TGA listed herbal substances/formulas which is useful.