Swift took a variety of useless medication for his 'giddiness.' These included asafoetida, the herb so foul-smelling that it is known as devil's dung, as well as 'nasty steel drops' (a crude iron supplement). Swift also took something that he called 'a vomit.' This vile treatment was based on the ancient Galenic theory of ridding the body of evil humours. It could have been one of many drugs, ranging from the merely unpleasant (ipecac) to the potentially toxic (arsenic or antimony). Had Swift taken arsenic or antimony only rarely, he probably would not have had long-term side effects, as most of the dose would have quickly left the body in the urine and from both ends of the gastrointestinal tract. His doctor pal John Arbuthnot prescribed confection of alkermes (a scarlet syrup in which the active ingredient was crushed parasitic insects), the vigorous laxative castor oil, and cinnabar of antimony (mercuric sulphide). Swift thought the cinnabar helped. This is just possible: some mercury compounds are mild diuretics.