These carnivorous plants have their primary origins in East Africa and Madagascar but are cultivated throughout the world. The main species originally used in cough preparations in Germany, D. rotundifolia, D. intermedia and D. anglica, are now rarely used currently due to threat of extinction. Instead, D. ramentacea and other Drosera species from Australia are employed. Herbal medicine preparations are made primarily from the roots, flowers, and fruit-like capsules.1
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Sundew has a long history of use for treating coughs and has been shown in one study to have cough-relieving abilities.
A number of herbs have a rich history of use for treating coughs due to colds, bronchitis, or other mild conditions. Only a few studies have examined the effectiveness of these herbs. However, their effectiveness is well-known by practitioners of herbal medicine the world over. Among those herbs that have been shown to have some degree of cough-relieving activity are marshmallow,3 sundew,4 and coltsfoot.5 Use of coltsfoot should be limited to preparations of the leaves and flowers only, as the root is high in pyrrolizidine alkaloids, constituents that may be toxic to the liver.
Thyme has a long history of use in Europe for the treatment of dry, spasmodic coughs as well as for bronchitis.6 Many constituents in thyme team up to provide its antitussive (preventing and treating a cough), antispasmodic, and expectorant actions. The primary constituents are the volatile oils, which include the phenols thymol and carvacol.7 These are complemented by the actions of flavonoids along with saponins. Thyme, either alone or in combination with herbs such as sundew, continues to be one of the most commonly recommended herbs in Europe for the treatment of dry, spasmodic coughs as well as for whooping cough.8 Because of its apparent safety, it has become a favorite for treating coughs in small children.
The historical use of sundew is similar to its use in modern herbal medicine. In 1685, Johann Schroder wrote in his book, The Apothecary or a Treasure Chest of Valuable Medicines, that sundew was a beneficial herb that “cures lung ailments and cures coughs.” Sundew tea was specifically recommended in Europe by herbalists for dry coughs, bronchitis, whooping cough, asthma, and “bronchial cramps.”2
Naphthaquinones are believed to give sundew the antispasmodic (or relief from coughing spasms) effect that has made it such a popular cough remedy in Europe.9 These naphthaquinones include plumbagin, ramentone, ramentaceon, and biramentaceone. Pharmacological studies show a clear antispasmodic effect in the respiratory tract.10 One naphthaquinone was found in an animal study to be comparable to codeine in its ability to suppress the impulse to cough. This finding has not been repeated in human studies, however. Based on this effect, sundew is often referred to as an herbal antitussive (a substance capable of preventing or relieving coughing). Human trials have shown its value either alone or in combination with other herbs for the treatment of coughs associated with bronchitis, pharyngitis, laryngitis, and even whooping cough.11
Adults and children older than 12 years of age may take 1/2–3/4 teaspoons (3 grams) per day.12 To prepare tea, boiling water is poured over 1/4–1/2 teaspoon (1 to 2 grams) of finely cut sundew root and above-ground parts, then strained after steeping for ten minutes. One cup (250 ml) may be taken three to four times daily. In Europe, liquid preparations of sundew are often combined with thyme, another antitussive, in cough syrups for adults and children. A tincture of sundew, 1/8–1/4 teaspoon (0.5 to 1.0 ml) three times per day, is also sometimes used.
At the recommended amounts, sundew is thought to be safe.13 Higher levels may lead to gastrointestinal irritation in some people. Pregnant and breast-feeding women should avoid use of sundew.
1. Wichtl M. Herbal Drugs and Phytopharmacetuicals. Boca Raton, FL: CRC Press, 1994, 178–81.
2. Schilcher H, Elzer M. Drosera (Sundew): A proven antitussive. Zeitschrift Phytotherapie 1993;14:50–4.
3. Nosal’ova G, Strapkova A, Kardosova A, et al. Antitussive action of extracts and polysaccharides of marshmallow (Althea officinalis L, var robusta). Pharmazie 1992;47:224–6 [in German].
4. Schilcher H. Phytotherapy in Paediatrics. Stuttgart: Medpharm Scientific Publishers, 1997, 38.
5. Wichtl M, Bisset N (eds). Herbal Drugs and Phytopharmaceuticals. Stuttgart: Medpharm Scientific Publishers and Boca Raton, FL: CRC Press, 1994.
6. Leung AY, Foster S. Encyclopedia of Common Natural Ingredients Used in Food, Drugs, and Cosmetics. New York: John Wiley and Sons, 1996, 492–5.
7. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. Montvale, NJ: Medical Economics, 1998, 1184–5.
8. Weiss RF. Herbal Medicine. Gothenburg, Sweden: Ab Arcanum and Beaconsfield, UK: Beaconsfield Publishers Ltd, 1988, 208–9.
9. Luckner R, Luckner M. Naphthaquinone derivative from Drosera ramentacea Burch. Ex harv. Et ond. Pharmazie 1970;25:261–5.
10. Krahl R. An effective principle from Drosera rotundifolia. Arzneim-Forsch Drug Res 1956;6:617–9.
11. Schilcher H, Elzer M. Drosera (Sundew): A proven antitussive. Zeitschrift Phytotherapie 1993;14:50–4.
12. Blumenthal M, Busse WR, Goldberg A, et al. (eds). The Complete German Commission E Monographs: Therapeutic Guide to Herbal Medicines. Austin: American Botanical Council and Boston: Integrative Medicine Communications, 1998, 217–8.
13. Newall CA, Anderson LA, Phillipson JD. Herbal Medicines: A Guide for Health-Care Professionals. London: The Pharmaceutical Press, 1996, 100.
Last Review: 05-01-2013
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