European, Chinese, and Ayurvedic herbal medicine emphasizes an individualistic approach to prescribing treatment - the practitioner determines the composition of an herbal medicine that's specifically designed for an individual patient. While evidence of the effectiveness of some herbal medicines has increased in recent decades, there have been very few clinical studies of tailored herbal prescriptions. However, the very nature of ad-hoc prescriptions combining different substances makes it necessary to evaluate the effectiveness and safety of the approach, ideally in a well-controlled clinical study.

British researchers have published the results of their review of such clinical studies in the Postgraduate Medical Journal. Three such studies were found, after an extensive search of medical journal. In the first, there were statistical trends favoring the active prescription over a matching placebo in treating osteoarthritis of the knee. In a study of patients with irritable bowel syndrome, the individualized herbal treatment was superior to placebo in four of five of the outcome measures made, but was inferior to standardized herbal treatment in all 5 outcomes. And in the third study, the prevention of chemotherapy-induced toxicity, the individualized herbal preparations were no better than placebo.

The investigators conclude that there is little evidence showing the effectiveness of individualized herbal medicine, and none of it is convincing enough to support its use. Clearly the practitioners who believe in this approach should be prepared to submit to further clinical trials. The risks of negative herb-herb and herb-drug interactions are sufficiently great to mandate such studies.