Purple Aster Root zǐ wǎn · 紫菀

Safety. A chronic cough needs a diagnosis before it is treated, and cough with blood in particular is a matter for medical assessment rather than self-management. Some Aster species are known to contain pyrrolizidine alkaloids, a class of compounds associated with liver injury in other herbs; whether material traded under this name carries a meaningful risk has not been established, and that uncertainty is a reason not to use it long-term or without professional guidance. Safety in pregnancy and breastfeeding is not established.