Adhatoda vasica (L.) Nees is a well-known plant drug in Ayurvedic and Unani medicine. It has been used for the treatment of various diseases and disorders, particularly for the respiratory tract ailments. Justicia adhatoda, commonly known in English as Malabar nut, adulsa, adhatoda, vasa, or vasaka, is a medicinal plant native to Asia, widely used in Siddha Medicine, Ayurvedic and Unani systems of medicine. The leaves of Adhatoda vasica contains phytochemicals such as alkaloids, tannins, saponins, phenolics and flavonoids. The most important is vasicine, a quinazoline alkaloid. The vasicine yield of the herbage has been measured as 0.541 to 1.1% by dry weight. This shrub has a number of traditional medicinal uses in Siddha Medicine, Ayurvedic and Unani systems of medicine. During the last 20 years, several scientific reports on oxytocic and abortifacient effects of vasicine and alkaloid derived from the plant have appeared. This leads to questions concerning the safety of A. vasica as a herbal medicine.