Tansy

Caution

Kynes says all parts of the plant, especially the flowers, are toxic if ingested, and that it is an abortifacient. The American Herbal Products Association says not to use it in pregnancy or lactation except under the supervision of a qualified healthcare practitioner, and not to exceed the recommended dose. It records contact dermatitis, with cross-reactivity to other daisy-family plants. It records that overdoses of tansy and its essential oil caused abdominal pain, vomiting, convulsions, seizures, coma, dilated pupils, irregular breathing and a fast, weak pulse, and that some were fatal. It notes thujone in some chemotypes of the oil, and attempted abortions with some fatal cases involving the essential oil. Wikipedia says the volatile oil can cause contact dermatitis, and that toxic metabolites form if it is taken internally. Cunningham's health key marks it P, a caution if pregnant.