Wormseed is a Central American herb that has been used for centuries to expel parasitic worms from the body[ 254 ]. The seed, or the essential oil obtained from the seed and flowering stem is used for this, though all parts of the plant are used medicinally. The plant, especially the essential oil, is toxic in larger doses and so should be used with care and preferably under the direction of a skilled practitioner[ 21 , 238 ]. This remedy should not be prescribed for pregnant women[ 238 ]. See also the notes above on toxicity. Until fairly recently, this was one of the most commonly used vermifuges, though it has now been largely replaced by synthetic drugs[ 222 ]. The seed, or the essential oil, was used[ 213 ]. It is very effective against most parasites, including the amoeba that causes dysentery, but is less effective against tapeworm[ 213 , 238 ]. Fasting should not precede its use and there have occasionally been cases of poisoning caused by this treatment[ 213 ]. The essential oil is used externally to treat athlete's foot and insect bites[ 238 , 240 ]. This is at its highest concentration in the flowering stems before seed is set, these contain around 0.7% essential oil of which almost 50% is the active vermifuge ascaridol[ 240 ]. The essential oil is of similar quality from plants cultivated in warm climates and those in cool climates[ 240 ]. The whole plant is analgesic, antiasthmatic, carminative, febrifuge, stomachic and vermifuge[ 1 , 4 , 21 , 57 , 145 , 147 , 171 ]. An infusion can be used as a digestive remedy, being taken to settle a wide range of problems such colic, diarrhoea and stomach pains; it is also used to treat conditions such as coughs, fevers and internal haemorrhages[ 254 , 348 ]. The leaves are added in small quantities as a flavouring for various cooked bean dishes because their carminative activity can reduce flatulence[ 222 ]. Externally, it has been used as a wash for haemorrhoids, as a poultice to detoxify snake bites and other poisons and is thought to have wound-healing properties[ 254 ]. The macerated leaves and flowers are mixed with a pinch of salt, and used as a poultice for treating persistent sores[ 348 ]. The essential oil is high in ascaridol, a nematicidal terpene peroxide which is active against ascaris, worms and ankylostomes[ 348 ].