Yew

Scientific Name(s): Taxus bacatta L., Taxus brevifolia Nutt., Taxus canadensis Marsh., Taxus cuspidata Sieb. and Zucc., Taxus floridana Nutt., Taxus yunnanensis
Common Name(s): Chinese yew, European yew, Ground hemlock, Japanese yew, Yew

Medically reviewed by Drugs.com. Last updated on Nov 22, 2023.

Clinical Overview

Use

Based on known toxicity, there are no current clinical uses of the plant. The semisynthetic taxane chemotherapy agent, docetaxel, was originally extracted from the needles of T. baccata.

Dosing

Crude preparations of yew needles or bark should not be used because of their cardiotoxic taxanes.

Contraindications

Contraindications have not yet been determined. There are no clinical uses of the plant due to toxicity.

Pregnancy/Lactation

There are no adequate and well-controlled studies of taxanes in pregnant women. However, animal studies have demonstrated embryo and fetotoxicity as indicated by intrauterine mortality, increased resorptions, and increased fetal deaths. Animal studies also have demonstrated high concentrations of taxenes in milk. Use in lactating women is not recommended.

Interactions

As most of the plant is poisonous, formal interaction studies have not been performed.

Adverse Reactions

The ingestion of the plant results in dizziness, dry mouth, mydriasis, and abdominal cramping. Rash and pale, cyanotic skin may develop. Eventually, ingestion may result in death.

Toxicology

Excluding the red aril, most of the plant is poisonous. Fatal and nonfatal suicidal yew ingestion has been documented as well as accidental poisonings in humans and animals.

Scientific Family

• Taxaceae

Botany

This evergreen is found throughout woods and forests and often is used as an ornamental hedge. The trunk supports a crown of spreading branches with long, narrow, dark green, shiny leaves. It is dioecious, with male and female flowers being produced on different trees. The ovoid seed is black and is surrounded by a red, fleshy covering called the aril. Yews flower in March and April.

History

The Celts coated their arrows with yew sap as a nerve poison. The alkaloid taxine has been used as an antispasmodic.Schauenberg 1990

Chemistry

The entire plant, with the exception of the red, fleshy aril, contains many taxane alkaloids, of which the best known is taxine.Cummins 1990 Other alkaloids (eg, milossine, ephedrine), the glycoside taxicatin and its derivativesSenilh 1984 and pigments are found throughout the plant family.

Uses and Pharmacology

Based on known toxicity, there are no current clinical uses of the plant.

Antibacterial activity against foodborne pathogens has been demonstrated with secondary bioactive metabolites produced from endophytic bacteria isolated from T. brevifolia seed, fruit, and leaves.(Islam 2018)

Dosing

Crude preparations of yew needles or bark should not be used because of their cardiotoxicity caused by taxanes.

Pregnancy / Lactation

Information regarding safety and efficacy in pregnancy and lactation is lacking. Avoid use.

Interactions

Formal drug interaction studies have not been performed with Yew ingestion.

Adverse Reactions

Hypersensitivity reactions

Cross-sensitivity to the chemotherapeutic agent docetaxel and paclitaxel has been reported in cancer patients with allergies to T. baccata.

Cardiovascular

Bradycardia and hypotension have been documented with ingestion of the plant.Michaud 2000

Toxicology

Lethal doses of yew leaves are highly species specific and minimum lethal dose can range from 0.6 to 1.3 g of leaves/kg in humans (approximately 5 mg of taxine/g of leaves), which is approximately 3 to 6.5 mg of taxine/kg of body weight.(Labossiere 2018) The adult lethal dose of yew needles is reported to be 50 g, which is equal to 250 mg of taxine alkaloids (approximately taxine 3 mg/kg body weight)(Grobosch 2013) that have been primarily implicated in inducing cardiac toxicity. Taxine B alkaloids mediate cardiac toxicity by blocking sodium/calcium channels and tend to be resistance to standard treatments. Taxus brevifolia, the Pacific yew, contains lower levels of taxine and tends to be less poisonous. Most cases of poisoning are highly resistant to pharmacologic treatment.(Labossiere 2018)

Excluding the red aril of the berries, most of the plant is poisonous. Following ingestion, symptoms of dizziness, dry mouth, mydriasis, nausea, vomiting, and abdominal cramping develop rapidly. A rash may appear, and the skin can become pale and cyanotic. Bradycardia, hypotension, ventricular tachycardia and fibrillation, and dyspnea may be accompanied by coma, leading to death caused by respiratory or cardiac failure. A number of deaths in humans have been reported following the ingestion of yew leaves or teas brewed from yew. The administration of digoxin-specific FAB antibody fragments has been associated with the improvement of cardiac conduction abnormalities following ingestion of yew leaves and berries(Cummins 1990, Labossiere 2018); intensive treatment with antiarrhythmic drugs, temporary pacemaker, intra-aortic balloon pump, excessive diuresis, extracorporeal membrane oxygenation, and extracorporeal life support may also be required.(Grobosch 2013) A 24-year-old woman with Asperger syndrome and a history of depression attempted suicide by ingesting yew leaves; cardiogenic shock developed within 5 hours of ingestion despite immediate stomach flushing, activated carbon, and tentative application of digitalis antitoxin. Prolonged CPR (almost 4 hours), 24-hour therapeutic hypothermia, repeat digitalis antitoxin, and 24 hours of medical and mechanical cardiac support established a stable sinus rhythm with regular atriventricular conduction and complete recovery of biventricular function. No neurological deficits, organ damage, or significant repolarization disorders were sustained.(Baum 2015)

A 22- year woman was admitted to the emergency room with apnea and no pulse after ingesting an unknown amount of Taxus baccata. Immediately before admission, the patient was witnessed to have experienced a generalized tonic clonic seizure. An electrocardiogram revealed a wide complex rhythm with persistent cardiovascular collapse. Despite supportive care, the patient died. Perimortem serum demonstrated 3,5-DMP concentrations of 86.9 ng/mL, and taxine B concentrations of 80.9 ug/mL.(Arens 2016) Yew-induced thrombocytopenia subsequent to consuming Chinese yew tea (T. yunnanensis) has been documented in a 53-year-old female that was confirmed with hospital re-challenge. Two other cases of yew-induced thrombocytopenia due to tea containing T. cuspidata extracts (Japanese yew) have also been reported.(Ubukawa 2019)

Several other cases of fatal and non-fatal intentional, as well as accidental, ingestion of yew leaves have been documented.(Grobosch 2013, Labossiere 2018)

References

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