Can Chinese medicine be boiled twice?Can you explain what toxicity in Chinese Medicine means?

 Q : Can Chinese medicine be boiled twice?

A: Sometimes the same set of ingredients can be boiled twice. When decocting for a second time, less water (approximately 500ml) is used or just enough to cover the surface of the ingredients. The two glasses of liquid that are obtained from both procedures are then mixed together; consume one in the morning and the other in the evening.
Medicinal materials that have a strong flavor and those with tonifying effect can usually be re-boiled. In order to extract most of the active ingredients, it is suggested to scoop out the medicinal residues and wrap them with a piece cloth and squeeze out the liquid, so as to fully utilize the active ingredients and not to let them get to waste. Medicine for treating influenza, for example, is not suitable for re-boiling. This is because the active ingredients of this medicine like peppermint and Amomum fruits can easily evaporate. If you "over cook" your decoction, it is best not to drink it as the chemical nature of the medicine has probably been altered. 
Q : Can you explain what toxicity in Chinese Medicine means?
A: Traditionally, Chinese medicines are divided into three categories: those with heavy toxicity, minor toxicity and no toxicity. According to Chinese medicinal pharmacology, serious toxic effects are coma, nausea, numbness in the mouth and in the limbs, which can be easily induced by drugs such as dried toad venom, unprocessed croton fruits and cinnabar. Medicines with minor toxicity like apricot seeds and ginkgo nuts, if used in high dosages, can cause mild breathing difficulties, abnormal heartbeat and dizziness. Drugs without toxicity, i.e., commonly used ingredients, are mild in nature and are less likely to have side effects. However, most TCMs are safe if applied according to syndrome differentiation and with the correct dosage for the appropriate length of time.