Sundew
Quick Facts
- What it is: A small carnivorous bog plant used in folk and Eclectic medicine as a cough remedy.
- Main uses: Dry, tickly cough, Spasmodic cough fits, Throat irritation and hoarseness
- Active ingredients: Plumbagin, Droserone, Hyperoside, Quercetin, Ellagic acid, Mucilage
- Forms: Cough syrup, Tincture, Dried herb for tea, Lozenges, Homeopathic Drosera
- Time to effect: Soothing within minutes if at all; judged over a few days
- Side effects: Usually mild: stomach upset, mouth or throat irritation, occasional skin rash.
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What is Sundew?
Sundew is a cough herb. It is a small carnivorous bog plant whose leaves are covered in sticky red hairs that trap insects. Herbalists dry the whole flowering plant and use it for dry, tickly, barking coughs.
The plant grows in peat bogs across Europe, Asia and North America. Wild round-leaved sundew is now protected in many countries. Most material sold today comes from farmed plants or from related Drosera species grown abroad.
American Eclectic doctors in the 1800s used it for spasmodic coughs, and European herbalists did the same. It still turns up in cough syrups, drops and tinctures sold in Europe.
The honest verdict on evidence: thin. Nearly every trial used sundew mixed with other herbs, so its own effect is unclear. A long record of traditional use is not proof that a remedy works, and it is not proof that it is safe.
How does Sundew work?
No one has shown how sundew works in people. The main idea is that it quiets the cough reflex and eases tightness in the airways.
In animal and isolated-tissue studies, naphthoquinones such as plumbagin appear to relax airway muscle. In test tubes, the same compounds slow some bacteria and lower markers of inflammation. Whether any of that happens in a human throat, at the small amounts in a syrup, is not established.
The plant also holds mucilage, a slippery gel-like fibre. Mucilage may coat and soothe a raw throat as you swallow it. That is a plausible local effect, not a proven one.
Flavonoids in the plant act as antioxidants in lab work. Antioxidant activity in a dish does not predict relief from a cough.
What forms does Sundew come in?
Sundew is sold in several forms:
- Cough syrups and drops, usually with other herbs such as thyme, ivy or plantain.
- Liquid tincture in alcohol, sometimes as drops in water.
- Dried herb for tea, though this is less common.
- Homeopathic Drosera, which is diluted so far that little or no plant material remains. That is a different product from the herbal extract, even though the name looks the same.
- Capsules and lozenges, mostly in blends.
Labels in Europe may carry a traditional herbal registration mark. That mark means the product is made to a quality standard and has a long history of use. It does not mean the remedy was proven to work in trials.
Where it comes from:
Sundew has a long folk record as a cough plant. Eclectic physicians in 19th-century America listed it for whooping cough, dry spasmodic cough and hoarseness. European herbals used it the same way, often as a syrup for children.
Older names hint at other claims. "Youthwort" and "lustwort" came from the belief that the dewy leaves preserved youth or stirred desire. Some writers also used the juice on warts and corns.
It entered formal pharmacy too. Sundew appeared in European pharmacopoeias and in homeopathic practice, where Drosera was a standard cough remedy. None of this history is described here as a reason to treat yourself.
Who should avoid Sundew?
- Do not use if you are pregnant or breastfeeding, as there is no safety data.
- Do not give it to children under 12 unless a doctor advises it.
- Do not use it in place of an asthma or COPD (a long-term lung disease) inhaler.
- Do not use it to treat whooping cough; that infection needs a doctor.
- Do not use it if you have ever reacted to sundew or to another Drosera product.
- Avoid alcohol-based tinctures if you take disulfiram or metronidazole, if you have liver disease, or if you avoid alcohol.
- Do not add it during cancer treatment unless your oncologist agrees.
- Never pick wild sundew; many species are protected by law, and handling the fresh plant can irritate skin.
When should you see a doctor?
Stop and see a doctor if any of these happen:
- Your cough lasts more than three weeks, or keeps coming back.
- You cough up blood, or thick green or brown phlegm.
- You have a fever, night sweats or losing weight without trying.
- You are short of breath, wheezing, or your chest hurts.
- You get a rash, itching or stomach pain after taking it.
Call emergency services for swelling of the lips, tongue or throat, or for sudden trouble breathing. That can be a severe allergic reaction.
Is Sundew legal where you live?
In the UK and much of the EU, sundew is sold as a traditional herbal medicine or as an ingredient in registered cough products. In the United States it is sold as a dietary supplement, and it is not approved by the FDA to treat any illness. Round-leaved sundew is a protected wild species in several countries, so picking it can be illegal.
Evidence grades and traditional-use labels are explained in our methodology. Nothing here is medical advice.
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