When the topic of traditional Asian medicine was first mooted, we were sceptical. To a magazine based in Europe and steeped in the history of science, there is much about traditional Asian medical practice that seems mystical and pseudoscientific. Other than well known success stories — artemisinin for malaria, and arsenic trioxide for leukaemia — there seemed to be a lack of scientifically proven remedies.

Yet a bit of probing revealed what a complex story this is. Not only are big efforts underway to modernize traditional medicine in China and Japan, but Western medicine is adopting some aspects of the Eastern point of view too. In particular, modern medical practitioners are coming around to the idea that certain illnesses cannot be reduced to one isolatable, treatable cause. Rather, a fall from good health often involves many small, subtle effects that create a system-wide imbalance.

But do traditional medicines actually work? Their personalized nature makes randomized controlled trials — the gold standard for testing drugs — extremely difficult. Rarely are two formulations identical. However, as modern medicine becomes more personalized, using biological and genetic markers, it is inadvertently developing the tools to better test traditional medicines.

Although artemisinin and arsenic trioxide are the archetypal examples of successful modern medicines mined from traditional Asian medicine, they do not represent the ideal convergence of the two systems. There are unique aspects to traditional Asian medicine that could hold great promise if they are artfully investigated. The goal of science should be to rigorously test each claim and sort the medical wheat from the pseudoscientific chaff.

We acknowledge the financial support of Saishunkan Pharmaceutical Co., ltd and Kitasato University Oriental Medicine Research Center in producing this Outlook. As always, Nature takes full responsibility for all editorial content.