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Yew

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American yew, chinwood, English yew, globe-berry, Japanese yew, Oregon yew, Pacific yew, Taxus baccata, T. brevifolia, T. canadenis, T. cuspidata, T. cuspididata, T. floridana, Western yew

The ancient Celts coated their arrows with yew sap as a nerve toxicant. The alkaloid taxine has been used as an antispasmodic. A tincture of the leaves had been used to treat rheumatism and liver and urinary tract conditions. Yew is obtained from bark and branch tips of Taxus brevifolia. It contains a mixture of about 19 taxane-type diterpene esters, referred to as taxines; most prominent of these are paclitaxel and taxine A and B. Other constituents include taxicatin, milossine, and ephedrine. Paclitaxel inhibits cell division by binding to the j3-tubulin subunit of microtubules, which prevents the disassembly of microtubules. Cells are thus arrested in mitosis. Yew is available as a tincture, capsules, and a salve of yew bark.

Reported uses

Yew is used to promote menstruation, eliminate tapeworms, and treat tonsillitis. Taxol, the trade name for the drug paclitaxel, is isolated from the bark of T. brevifolia. Taxotere is the trade name of docetaxel, a more potent analogue of paclitaxel. Paclitaxel is FDA-approved for treating metastatic, ovarian, and breast cancers.

Administration

  • For cancers: Optimal doses and administration protocols are still being determined in ongoing clinical trials
  • Infusion (bark or needles are added to 1 cup hot water): The infusion is taken by mouth once every day
  • Tinctures: Doses of yew bark tinctures vary widely.

Safety Risk Most parts of the yew plant are highly poisonous. Ingestion of 50 to 100 g of yew needles or berries has been fatal and is especially dangerous in children. Treatment includes digoxinspecific fragment antigen binding antibodies and gastric lavage followed by administration of charcoal. Supportive measures to treat cardiac effects and other symptoms may also be indicated.

Hazards

Yew may cause dizziness, unconsciousness, bradycardia, tachycardia, hypotension, cardiac failure, mydriasis, dry mouth, reddened lips, abdominal cramps, nausea, vomiting, dyspnea, respiratory failure, rash, pallor, and cyanosis. It may also cause miscariage.

Potentiation of myelosuppression and interactions occurs when yew is taken with other chemotherapeutic drugs. Advise patient to use together only with extreme caution and only under direct supervision of a health care provider.

Women who are pregnant or breast-feeding shouldn’t use yew. Because of the potential extreme toxicity of multiple constituents, herbal formulations of the yew tree should be used only with extreme caution, if at all.

Clinical considerations

  • Monitor vital signs and electrocardiogram iflarge amounts of yew are ingested.
  • Because of the potential extreme toxicity of yew, only prescription forms of paclitaxel should be used, and then only under the careful guidance of an oncologist.
  • Some common hypersensitivity reactions to paclitaxel have been reduced by giving the drug as a slow infusion over 6 to 24 hours.
  • Advise patient of the need for regular follow-up care with an oncologist if taking yew for a cancerous condition.
  • Urge patient to report adverse effects promptly to a health care provider.
  • Tell patient to seek emergency medical care if he develops adverse effects or a toxic response.
  • Warn patient of the danger of taking yew without medical supervision.
  • Warn patient to keep all herbal products away from children and pets.
  • Tell patient to remind pharmacist of any herbal and dietary supplements that are being taken when filling a new prescription.
  • Advise patient to consult with a health care provider before using an herbal preparation because a conventional treatment with proven efficacy may be available.

Research summary

Clinical trials in the use of the FDA-approved drug paclitaxel are ongoing to determine treatment approval for other cancers, and optimal dose and administration protocols.

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