foxglove

n.

1. Any of several herbs of the genus Digitalis, especially D. purpurea of Europe, having a long cluster of large, tubular, pinkish-purple flowers and leaves that are the source of the drug digitalis.
2. Any of several related plants.

[From the resemblance of its flowers to the fingers of a glove.]

For more information on foxglove, visit Britannica.com.

Description

Foxglove, also called Digitalis purpurea, is a common biennial garden plant that contains digitoxin, digoxin, and other cardiac glycosides. These are chemicals that affect the heart. Digitalis is poisonous; it can be fatal even in small doses. It was the original source of the drug called digitalis.

Foxglove is a native of Europe. It was first known by the Anglo-Saxon name foxes glofa (the glove of the fox), because its flowers look like the fingers of a glove. This name is also thought to be related to a northern legend that bad fairies gave the blossoms to the fox to put on his toes, so that he could muffle his footfalls while he hunted for prey. The legend may account in part for some of the common names of digitalis: dead man's bells, fairy finger, fairy bells, fairy thimbles, fairy cap, ladies' thimble, lady-finger, rabbit's flower, throatwort, flapdock, flopdock, lion's mouth, and Scotch mercury.

Foxglove was first introduced to the United States as an ornamental garden plant. During the first year, foxglove produces only leaves. In its second season it produces a tall, leafy flowering stalk that grows 3–4 ft (0.9–1.2 m) tall. In early summer, many tubular, bell-shaped flowers bloom; they are about 2 in (5.08 cm) long and vary in color from white to lavender and purple.

Foxglove was originally used for congestive heart failure and atrial fibrillation (chaotic contractions across the atrium of the heart). Foxglove helps the muscles of the heart to contract, reduces the frequency of heartbeats, and lowers the amount of oxygen the heart needs to work. The cardiac glycosides in foxglove block an enzyme that regulates the heart's electrical activity. The dried leaves, ripe dried seeds, and fresh leaves of the one-year-old plant, or the leaves of the two-year old plant are the parts that were used in medicine.

In spite of its use in the past, foxglove has been largely replaced as a heart medicine by standardized pharmaceutical preparations because it is one of the most dangerous medicinal plants in the world. Foxglove is, in fact, a useful example of the importance of standardization in testing the efficacy and possible toxicity of present-day popular herbal medicines. Its sap, flowers, seeds, and leaves are all poisonous; the leaves, even when dried, contain the largest amount of cardiac glycosides. The upper leaves of the stem are more dangerous than the lower leaves. Foxglove is most toxic just before the seeds ripen. It tastes spicy hot or bitter and smells slightly bad.

In folk medicine, foxglove was first used in Ireland. Its use spread to Scotland, England, and then to central Europe. It was taken to treat abscesses, boils, headaches, paralysis, and stomach ulcers. It was also applied to the body to help wounds heal and to cure ulcers. It has not been proven to be an effective treatment for any of these ailments.

In 1775, William Withering, an English doctor, first discovered the accepted medicinal use of foxglove. He identified digitalis as a treatment for swelling or edema

associated with congestive heart failure. Withering published a paper in 1785 that is considered a classic in the medical literature. Foxglove was used to treat heart disease during the eighteenth and nineteenth centuries.

General Use

Foxglove is no longer used as a heart medicine because the therapeutic dose and the lethal dose are very close. Seasonal variations in the level of cardiac glycosides in the plant make the safe dose impossible to estimate except by an experienced physician and prescriber of the herb who monitors the patient on an hourly basis for signs of overdose. Few living doctors and herbalists can safely use digitalis as a plant extract. Specific standardized doses of pharmaceutical digoxin are used instead. Even so, patients receiving the drug must be closely monitored.

Preparations

In present-day usage, foxglove is used as an ingredient in a class of heart drugs called digitalis. Digoxin (Lanoxin) is the most common drug made from digitalis. Digitalis is usually taken orally, as capsules, as an elixir, or as tablets. It can also be given in an injection.

Precautions

Used improperly, foxglove is deadly; it can make the heart stop or cause a person to suffocate. Eating any part of the plant can be fatal. The therapeutic dose of foxglove is very close to the lethal dose. Foxglove should therefore not be used.

An overdose of foxglove interferes with the heart's normal electrical rhythms; it can make the heart beat too slowly or cause extra heartbeats. An overdose of foxglove may also cause diarrhea, headache, loss of appetite, and vomiting. More serious and potentially deadly reactions to an overdose affect the heart and the central nervous system. Foxglove can disrupt the heart's rhythm, including life-threatening ventricular tachycardia, or atrial tachycardia with atrioventricular block. In the central nervous system, foxglove can cause confusion, depression, drowsiness, hallucinations, psychoses, and visual disturbances.

Poisoning from foxglove occasionally occurs from the misuse of such herbal preparations as dried foxglove leaves used in a tea, or from overdoses of prescribed digitalis. It can also occur when foxglove is confused with comfrey, a plant used for tea that belongs to the borage family. The two herbs look very much alike.

Side Effects

Some patients who take pharmaceutical preparations of digitalis may experience such side effects as too much muscle tone in the stomach and intestines, diarrhea, headache, loss of appetite, and vomiting. These side effects are the same as some symptoms of a foxglove overdose. Digitalis preparations can have toxic side effects due to overdose or other conditions. The most serious are arrhythmias, abnormal heart rhythms that can be life-threatening.

Interactions

The use of digitalis can increase the toxicity of other cardioactive drugs. Hypersensitivity to digitalis, dehydration, or the use of diuretics that cause people to lose fluids and salts may increase the risk of side effects from digoxin. The risk of cardiac arrhythmias is increased when people taking digitalis also take amphetamines or diet pills; medicine for asthma or other breathing problems; or medicine for colds, sinus problems, hay fever, or other allergies. Taking any of these drugs with digitalis also affects how much digitalis is in the body and how effective it will be.

Resources

Books

PDR for Herbal Medicines. Montvale, NJ: Medical Economics Company, 1998.

Periodicals

Dickson, C. "Mountain Healing: Medicinal Plants of the Southern Appalachians." Mother Earth News 173 (1999): 18.

Goldman, Peter. "Herbal Medicines Today and the Roots of Modern Pharmacology." Annals of Internal Medicine 135 (October 16, 2001): 594–600.

Other

Sievers, A. F. "Foxglove." The Herb Hunters Guide. Washington, DC: Miscellaneous Publication, No. 77. 1930 [cited December 2002]. .

[Article by: Lori De Milto; Rebecca J. Frey, PhD]

In 1870 the naturalist James Britten launched the theory that ‘foxglove’ means ‘glove of the Little Folks’ or fairies, since the flower is called ‘witches' thimbles' in North Country dialect, and ‘fairy's petticoat’ in Cheshire. This pretty whimsey has often been repeated, but reference to the Oxford English Dictionary and the English Dialect Dictionary shows it to be nonsense. The word is attested from AD 1000 onwards, always as ‘fox-’ and never as ‘folks-’; there are several other plants with ‘fox’ in their names; in Norway, the flower is called revbjelde, ‘fox-bell’. Nor is there any instance of ‘folk’ being used without any defining adjective to mean ‘fairies’.

There are few traditions about foxgloves. In north Devon they are said to have sprung up wherever the blood of St Nectan, a locally revered saint, dripped on the ground after he was beheaded; one Staffordshire man stated, in 1917, that ‘I don't like them, missus; they mean war. Them foxgloves is soldiers.’

They are one of the few plants whose curative properties have been tested and accepted by orthodox medicine. A scientist named William Withering was asked, in 1775, to examine a herbal drink used in Shropshire to cure dropsy, and correctly identified foxglove leaves as its most effective ingredient. This led to the scientifically controlled use of digitalin to treat various types of heart disease—although, wrongly used, foxgloves can also cause fatal heart failure.

The healing powers, real and supposed, of the tall plant with distinctive white or purple flowers (genus digitalis) have been known since classical times. Poisonous if swallowed, it is applied externally for sprains, bruises, and bone ailments. In Gaelic and Welsh traditions its powers are thought to flow from the realm of the fairy; its name means literally ‘fairy fingers’ [méirini púca] or ‘fairy thimble’ [méaracán sídhe] in Irish and ‘banshee herb’ in Scottish Gaelic [lus-nam-ban-s'th; cf. Irish lus na mban sídhe]. Its prestige in Ireland is shown in the Hiberno-English word for foxglove, lusmore [Irish lus mór, great herb]. Manx sleggan; Welsh bysedd y cw^n [dog finger]; Cornish mannek lowarn [foxglove]; Breton bruluenn.

digitalis purpurea.

Dansk (Danish)
n. - fingerbøl

Nederlands (Dutch)
vingerhoedskruid

Français (French)
n. - digitale

Deutsch (German)
n. - (bot.) Fingerhut

Ελληνική (Greek)
n. - (φυτολ.) κορακόχορτο, χελιδονόχορτο

Italiano (Italian)
digitale

Português (Portuguese)
n. - dedaleira (f) (Bot.)

Русский (Russian)
наперстянка

Español (Spanish)
n. - dedalera, digital

Svenska (Swedish)
n. - fingerborgsblomma

中文（简体）(Chinese (Simplified))
毛地黄, 指顶花

中文（繁體）(Chinese (Traditional))
n. - 毛地黃, 指頂花

한국어 (Korean)
n. - digitalis(식물의 디기탈리스)

日本語 (Japanese)
n. - キツネノテブクロ

العربيه (Arabic)
‏(الاسم) قفاز الثعلب‏

עברית (Hebrew)
n. - ‮אצבעונית (צמח-נוי)‬

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