← The ApothecaryGelsemiaceaewhole plant (external use only in classical Chinese texts), roots and leaves (source of alkaloids)Fact-checked 24 October 2026

Toxic — not for home useThe whole plant is poisonous, the root bark most of all. Total alkaloids by mouth killed half of test mice at about 15 mg/kg. In a review of 160 hospitalised patients in China (13 studies, 2000–2024), 18.75% died, mostly after mistakenly drinking soups or medicinal liquors containing the plant; poisoning can progress to respiratory failure within half an hour. There is no specific antidote: treatment is airway protection, mechanical ventilation and supportive care, with gastric lavage only once the airway is secured; naloxone, and in animals securinine and flumazenil, have shown some benefit.In an emergency, call your local emergency number or poison centre.

Heartbreak grass

Gelsemium elegans

Also calledGou wen (Chinese, 鉤吻) · Duan chang cao (Chinese, 斷腸草) · Lá ngón (Vietnamese) · Graceful jesamine

In older monographsMedicia elegans, Gelsemium sumatranum

A yellow-flowered climber of southern China and South-East Asia and one of the most poisonous plants in the region. Classical Chinese herbals recorded it only for external use against swelling, itch and parasites because of its toxicity. It is now studied for its alkaloids, chiefly koumine, but the effective dose is close to the toxic dose and it still causes fatal poisonings, mostly when its roots or flowers are mistaken for other herbs. It is not a home remedy in any form.

What it is used for

Pain (general)
Limited
Total alkaloids, koumine and gelsemine reduced pain in mouse and rat models (including diabetic nerve pain) without the tolerance seen with morphine. There are no controlled human trials, and the therapeutic dose is close to the toxic dose.¹
Psoriasis
Limited
Used in China for skin diseases including psoriasis and neurodermatitis; koumine reduced epidermal over-growth in mouse models. No human trials.¹
Lice and scabies
Traditional
The Shennong Bencao Jing and Bencao Gangmu record external use to 'kill insects' and relieve itching, reduce swelling and 'dispel wind', never internal use, because of its toxicity.¹

Safety

Pregnancy: Contraindicated
Breastfeeding: Contraindicated
Children: Not for any use.

Interactions with medicines

sedatives (barbiturates, chloral hydrate)MajorGelsemium alkaloids enhanced their hypnotic effect in animals; any combination adds to respiratory depression.

Interaction checker →

Do not use if

Any internal use
Any home use

Side effects

Dizziness, blurred vision, numbness and weakness within about 20 minutes of ingestion
Nausea, vomiting and abdominal pain
Convulsions, coma
Respiratory depression and failure; slowed heart rate and low blood pressure

Dangerous lookalikes

Flowers are mistaken for honeysuckle (Lonicera japonica), and roots for Millettia speciosa or Ficus hirta used in herbal soups — a common cause of poisoning in southern China.

In the healing traditions

Traditional Chinese Medicine
Gou wen / Duan chang cao
Used externally to dispel wind, reduce swelling, remove poison, kill insects and relieve itching. Legend holds that Shennong himself was fatally poisoned by it, which led to the name duan chang cao. In southern China it is still put in medicinal liquors, which some middle-aged and older men believe 'tonify the kidney'; most such fatal cases are men.
Shennong Bencao Jing; Bencao Gangmu
Modern pharmacology
Koumine, gelsemine, gelsenicine
Nearly 100–120 monoterpenoid indole alkaloids in six structural classes. Koumine (the most abundant) is studied for pain, anxiety, inflammation and tumours in the laboratory; gelsenicine (the most toxic) stimulates GABA-A receptors in the brainstem breathing centre, stopping respiration. GEB alkaloid eye drops dilated the pupils in 69 volunteers in a 1990 Chinese study.

Active compounds

koumine: most abundant alkaloid; analgesic, anxiolytic and anti-inflammatory in animals; mouse LD50 about 99 mg/kg by injection
gelsemine: modulates glycine and GABA-A receptors; mouse LD50 about 56 mg/kg by injection
gelsenicine: the most toxic alkaloid (mouse LD50 about 0.1–0.2 mg/kg); inhibits the brainstem respiratory neurons through GABA-A receptors

History

Its extreme toxicity was recorded in the Shennong Bencao Jing more than 2,000 years ago, and legend makes Shennong its most famous victim. Chinese scientists began studying its chemistry and pharmacology in the 1930s, and from the 1980s its alkaloids were tried for tumours, inflammation and pain, but clinical use has stayed limited by the narrow gap between helpful and lethal doses.

Sources

Reference, not prescription. Nothing here is medical advice. Herbs can interact with medicines and be dangerous in pregnancy; tell your doctor or pharmacist about anything you take.