Here's some sample research results - I prefer this to anecdotal reports since there are larger sample groups and controlled studies - I stuck with scientific journals rather than wikipedia type sources, searched on 'traditional chinese medicine risks'. I think you'd need to know what specific herbs the practitioner wants to use and then look those up for posisble toxicity etc. A few universities are studing alternative medical therapies and publish good research - I think you'll find a lot of information is available.
archfami.ama-assn.org/cgi/content/full/9/10/1071
Risks Associated With the Practice of Traditional Chinese Medicine
An Australian Study
Alan Bensoussan, MSc(Res); Stephen P. Myers, ND, BMed, PhD; Anne-Louise Carlton, BSc, MBA
Arch Fam Med. 2000;9:1071-1078.
ABSTRACT
Objective To investigate the nature and frequency of adverse events that occur as a result of the practice of traditional Chinese medicine (acupuncture and Chinese herbal medicine) in Australia.
Methods Data on adverse events were obtained as part of a comprehensive survey of all occupational health groups, government-registered and unregistered, who practiced traditional Chinese medicine or 1 of its main modalities.
Results Practitioners reported numerous adverse events arising from the application of acupuncture (including fainting, nausea and vomiting, and increased pain), or the consumption of Chinese herbal medicines (including direct toxic effects and allergic reactions). Practitioners experienced an average of 1 adverse event every 8 to 9 months of full-time practice or 1 adverse event for every 633 consultations. The mean adverse event rate of nonmedical practitioners was less than half the mean adverse event rate of medical practitioners.
Conclusions The practices of acupuncture and Chinese herbal medicine are not risk-free and fatalities have occurred. Variation in adverse event rates between medical and nonmedical practitioners may reflect differences in relevant education or different reporting behaviors. These data represent the first step in the evaluation of adverse event rates in traditional Chinese medicine.
www.ncbi.nlm.nih.gov/pubmed/19651200
2009 Oct 29;126(1):18-30. Epub 2009 Aug 3.
Aconitum in traditional Chinese medicine: a valuable drug or an unpredictable risk?
Singhuber J, Zhu M, Prinz S, Kopp B.
Department of Pharmacognosy, University of Vienna, Vienna, Austria.
Abstract
Aconitum species have been used in China as an essential drug in Traditional Chinese Medicine (TCM) for 2000 years. Reviewing the clinical application of Aconitum, their pharmacological effects, toxicity and detoxifying measures, herb-herb interactions, clinical taboos, famous herbal formulas, traditional and current herbal processing methods based upon a wide range of literature investigations serve as a case study to explore the multidisciplinary implications of botanicals used in TCM. The toxicological risk of improper usage of Aconitum remains very high, especially in countries like China, India and Japan. The toxicity of Aconitum mainly derives from the diester diterpene alkaloids (DDAs) including aconitine (AC), mesaconitine (MA) and hypaconitine (HA). They can be decomposed into less or non-toxic derivatives through Chinese traditional processing methods (Paozhi), which play an essential role in detoxification. Using Paozhi, the three main forms of processed aconite -- yanfuzi, heishunpian and baifupian -- can be obtained (CPCommission, 2005). Moreover, some new processing techniques have been developed in China such as pressure-steaming. The current development of fingerprint assays, in particular HPLC, has set a good basis to conduct an appropriate quality control for TCM crude herbs and their ready-made products. Therefore, a stipulation for a maximum level of DDA content of Aconitum is highly desirable in order to guarantee the clinical safety and its low toxicity in decoctions. Newly developed HPLC methods have made the accurate and simultaneous determination and quantification of DDA content interesting.