All medicines pose a potential health risk, be they Eastern or Western medicines. Newly developed Western drugs must undergo rigorous testing to ensure their efficacy and safety, while with Eastern drugs, safety has generally been established because of their long histories of safe usage as traditional medicines. The regulation of Western medicines is much stronger than that of Eastern medicines, partly as pure chemicals are used and their effects and side effects are more likely to be acute. Eastern medicines consist of multiple components, generally extracted from a single or several plants or other natural sources, and their effects are not so acute, with delayed onset of side effects. However, the chronic usage of many Eastern medicines may result in the gradual accumulation of toxic compounds in the body. For example, Agaricus blazei extracts have been used as alternative medicines for cancer, but contain the known carcinogen agaritine (this carcinogen is also present in Agaricus bisporus). To ensure the safety of this alternative medicine, agaritine should be removed or its content reduced if the extract is to be taken chronically. Clearly, the safety of not only pure medicines, but also alternative medicines and daily foods, should be carefully controlled.