Withering's Account of the Foxglove

In 1775 William Withering was asked his opinion of a family recipe for dropsy that an old woman in Shropshire had long kept secret. She had sometimes cured patients after regular practitioners had failed, and her medicine was said to cause violent vomiting and purging. It contained twenty or more herbs, but Withering knew his botany and saw that the active one could only be foxglove, the plant Fuchsius had named Digitalis in 1542 after the German Fingerhut, a finger-stall, because its flowers looked like the finger of a glove.

Learning to use it took him ten years. In 1777 he was still ordering a decoction of three drams of the dried leaves, a dose he later said he had got wrong. By 1785 his advice was to give it slowly, in measured doses at intervals, and to continue only until the medicine acted on the kidneys, the stomach, the pulse or the bowels, stopping at the first sign of any of these.

An Account of the Foxglove is dated from Birmingham on 1 July 1785, when Withering was physician to the General Hospital there. It sets out 163 numbered cases. He wrote that it would have been easy to pick only the successes, and that he had instead included every patient to whom he had given foxglove, proper or improper, successful or otherwise. Some cases failed, and at least one records nausea after the drug was continued for a week without a break.

His conclusions included that foxglove could be used in every kind of dropsy except the encysted, and that it had a power over the motion of the heart not seen with any other medicine. He also told readers to gather the plant fresh each season, because leaves kept into a second year lost much of their strength. The James Lind Library lists the book under reporting bias, citing Withering's appeal for caution when reporting on a new medicine.