Janis thorn

Janis thorns were small, poisonous thorns used by the Sevateem as weaponry. Their poison caused first paralysis and then death in humans.

Though there is no naturally occurring cure, an anti-toxin was created by the Fourth Doctor using a bioanalyzer. (DW: The Face of Evil)

Leela frequently used janis thorns, which she fired through a blowpipe. In Victorian London, she used one to kill a Chinese assassin threatening the Doctor. (DW: The Talons of Weng-Chiang)