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Botanical names:
Drosera anglica, Drosera intermedia, Drosera ramentacea, Drosera rotundifolia

Parts Used & Where Grown

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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Our proprietary "Star-Rating" system was developed to help you easily understand the amount of scientific support behind each supplement in relation to a specific health condition. While there is no way to predict whether a vitamin, mineral, or herb will successfully treat or prevent associated health conditions, our unique ratings tell you how well these supplements are understood by the medical community, and whether studies have found them to be effective for other people.

For over a decade, our team has combed through thousands of research articles published in reputable journals. To help you make educated decisions, and to better understand controversial or confusing supplements, our medical experts have digested the science into these three easy-to-follow ratings. We hope this provides you with a helpful resource to make informed decisions towards your health and well-being.

3 Stars Reliable and relatively consistent scientific data showing a substantial health benefit.

2 Stars Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.

1 Star For an herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support.

This supplement has been used in connection with the following health conditions:

Used for Why
1 Star
Refer to label instructions
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,, and coltsfoot. 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. 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. These are complemented by the actions of flavonoids along with saponins. Thyme, either alone or in combination with herbs such as , 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. Because of its apparent safety, it has become a favorite for treating coughs in small children.

Traditional Use (May Not Be Supported by Scientific Studies)

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

How It Works

Botanical names:
Drosera anglica, Drosera intermedia, Drosera ramentacea, Drosera rotundifolia

How It Works

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.3 These naphthaquinones include plumbagin, ramentone, ramentaceon, and biramentaceone. Pharmacological studies show a clear antispasmodic effect in the respiratory tract.4 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.5

How to Use It

Adults and children older than 12 years of age may take 1/2–3/4 teaspoons (3 grams) per day.6 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.


Botanical names:
Drosera anglica, Drosera intermedia, Drosera ramentacea, Drosera rotundifolia

Interactions with Supplements, Foods, & Other Compounds

At the time of writing, there were no well-known supplement or food interactions with this supplement.

Interactions with Medicines

As of the last update, we found no reported interactions between this supplement and medicines. It is possible that unknown interactions exist. If you take medication, always discuss the potential risks and benefits of adding a new supplement with your doctor or pharmacist.
The Drug-Nutrient Interactions table may not include every possible interaction. Taking medicines with meals, on an empty stomach, or with alcohol may influence their effects. For details, refer to the manufacturers' package information as these are not covered in this table. If you take medications, always discuss the potential risks and benefits of adding a supplement with your doctor or pharmacist.

Side Effects

Botanical names:
Drosera anglica, Drosera intermedia, Drosera ramentacea, Drosera rotundifolia

Side Effects

At the recommended amounts, sundew is thought to be safe.7 Higher levels may lead to gastrointestinal irritation in some people. Pregnant and breast-feeding women should avoid use of sundew.

Related Information

  1. What Are Depletions & Interactions?


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. Luckner R, Luckner M. Naphthaquinone derivative from Drosera ramentacea Burch. Ex harv. Et ond. Pharmazie 1970;25:261-5.

4. Krahl R. An effective principle from Drosera rotundifolia. Arzneim-Forsch Drug Res 1956;6:617-9.

5. Schilcher H, Elzer M. Drosera (Sundew): A proven antitussive. Zeitschrift Phytotherapie 1993;14:50-4.

6. 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.

7. Newall CA, Anderson LA, Phillipson JD. Herbal Medicines: A Guide for Health-Care Professionals. London: The Pharmaceutical Press, 1996, 100.

Last Review: 04-14-2015

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The information presented by TraceGains is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires December 2021.

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