Digitalis purpurea

Or (common foxglove)

Medicinal Uses

Foxgloves are a source of digitoxin, a glycoside used in the drug digitalis, which has been used as a heart stimulant since 1785. It is also well-known for its toxicity, and ingestion of the leaves (usually as a result of misidentification for comfrey, Symphytum officinale) can result in severe poisoning.

Despite their toxicity, they have been widely used in folk-medicine. Foxglove tea (an infusion of the leaves) was taken for colds, fevers and catarrh, and compresses were used for ulcers, swellings and bruises. Its most common use was as a diuretic against dropsy (accumulation of fluid in the tissues), for which it was sometimes effective, but occasionally proved fatal.

William Withering, an 18th century botanist and physician, studied the medicinal use of foxgloves, in particular their use in the treatment of dropsy. He discovered that an infusion of the leaves could slow and strengthen the heartbeat, which in turn stimulated the kidneys to clear the body and lungs of excess fluid. He also showed that foxglove leaves could be used in the treatment of heart failure (but that high doses could stop the heart).

Withering’s An Account of the Foxglove and Some of its Medical Uses: with Practical Remarks on Dropsy, and Other Diseases (1785) is a landmark publication, being the first English text in which the therapeutic effects of a drug are described, and is considered by some to mark the birth of modern pharmacology. Withering’s work led to the eventual isolation and purification of digitoxin and digoxin (cardiac glycosides used in modern medicine as heart stimulants in the drug digitalis).

Today, digitalis is normally made using Digitalis lanata leaves (although during the Second World War D. purpurea seeds were collected from the wild and grown to produce large quantities of leaves for medicinal use).

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