What is purple tongue?

Our tongue coating generally does not show purple, but our tongue sometimes shows purple tongue due to disease reasons. For example, the whole tongue is purple, or some parts show purple petechiae. We collectively call it purple tongue. Its main reason is that qi and blood circulation are not smooth enough, qi stagnation and blood stasis are caused. In western medicine, it is normal because of high blood viscosity or hyperlipidemia or some diseases, such as heart failure, emphysema and other reasons. Normally, if the whole tongue is purple, its disease is mostly caused by systemic qi stagnation and blood stasis. If a certain part shows purple spots, it may be caused by local blood stasis tissue or local blood collateral damage. If the tongue is pale red and purple, it is mostly caused by lung qi stagnation, liver blood stasis, or qi deficiency and blood circulation weakness. If the tongue is red and purple, then most of this situation is caused by intense heat and toxin, which enters the blood and consumes body fluid. It was caused by qi and blood stagnation.