By Joanna Wolstenholme
The foxglove, it seems, is more than just a pretty flower. Now a wide stream drug – with the trade name of digoxin – used to treat congestive heart failure, it has been used in folk medicine since at least 1596.
Traditional herbals – compendiums of folk knowledge, accumulated and added to over the years and generations – are a mine of knowledge for possible new drug sources. William Withering, a forward thinking gentleman [s1] of the 18th century, understood this in a time when many dismissed such folk knowledge as witchcraft. He took a claim from John Gerard’s 1596 Herball that ‘Fox gloue boiled in water and wine…. Openeth also the stopping of the liver, spleene and milt and other inward parts’. This claim for the effects of the foxglove on the internal organs caught the curiosity of Withering, and he investigated further to find that foxglove was an effective cure for dropsy, a swelling of the limb and torso; a disease we now know is due to the inadequate pumping of the heart.
This use for foxglove was brought to the light after Withering’s conversations with a wise old woman in Shropshire, who had a family recipe for the cure of dropsy. Withering’s knowledge of herbs and the human body (he had training both as a doctor and a botanist, only truly becoming interested in botany after being asked to collect flowers for his sweetheart to paint) allowed him to isolate foxglove from the 20 odd herbs in the lady’s magic potion. He humbly commented later that it was ‘not very difficult for one conversant in such subjects, to perceive, that the active herb could be no other than foxglove’.
Withering went on to prescribe infusions of the leaves, and ground dried leaf powder, as a cure for dropsy. Modern reanalysis of the data that Withering recorded of his patients shows that he had a 65-80% success rate – good even by today’s standards. Powdered foxglove – now sold as Digitoxin, but still extracted from countless hundreds of foxgloves – is still prescribed to treat congestive heart failure, an underlying case of dropsy.
Stories such as these surely tell us that we cannot simply dismiss knowledge held in ancient herbals as nonsense, or witchcraft. Whilst those recording these cures may not have known how they work at the molecular level, nor conducted double blind trials, but they recorded potions and infusions that they knew to be successful. What worked then, in an age of ignorance of what caused terrifying ailments, will work now, in an age where we have the ability to extract the active compounds, and even synthesise analogues with fewer side effects.