Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism.[1] Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a substructure of the organism, such as a cell (cytotoxicity) or an organ such as the liver (hepatotoxicity). By extension, the word may be metaphorically used to describe toxic effects on larger and more complex groups, such as the family unit or society at large. Sometimes the word is more or less synonymous with poisoning in everyday usage.

A central concept of toxicology is that the effects of a toxicant are dose-dependent; even water can lead to water intoxication when taken in too high a dose, whereas for even a very toxic substance such as snake venom there is a dose below which there is no detectable toxic effect. Considering the limitations of this dose-response concept, a novel Drug Toxicity Index (DTI) has been proposed recently.[2] DTI redefines drug toxicity, identifies hepatotoxic drugs, gives mechanistic insights, predicts clinical outcomes and has potential as a screening tool. Toxicity is species-specific, making cross-species analysis problematic. Newer paradigms and metrics are evolving to bypass animal testing, while maintaining the concept of toxicity endpoints.

Taxus baccata is one of the most poisonous trees in the world. It contains taxanes and toxic alkaloids: the most dangerous one is the taxine. It is a fairly common plant in our environment and could be extremely dangerous; however, yew poisoning is quite rare. Cases may occur by voluntary or accidental ingestion. Therefore, the rapid orientation and diagnosis of suspected episode are important, in order to treat it quickly. There are no specific clinical or analytical alterations in this intoxication and it is very difficult to determine in each case the evolution of the episode. Patients who ingest a lethal dose frequently die due to cardiac arrest, in spite of resuscitation efforts. At present, no specific therapy exists. Therapeutic procedures reported in the literature are only referred to in published case reports, so there is insufficient evidence to recommend any treatment in yew poisoning. In our case report, we describe poisoning by ingestion of Taxus baccata leaves in a suicide attempt, its clinical evolution and its management and we do a brief review of the literature about yew poisoning.

Yew (Taxus spp.) is a coniferous tree of the Taxaceae family, typical of mountainous areas with cool and humid environments. It contains taxanes and toxic alkaloids (such as taxine). There are many species and one of them is Taxus baccata [1]. Taxus baccata is a species of the genus Taxus, one of the most toxic trees in the world. It grows slowly, reaching a longevity up to 5000 years. They rarely form forests, being commonly found as isolated individuals. It is a conifer with a persistent leaf that can reach 20 meters high, although usually they don´t exceed the size of a small tree. The trunk is usually thick and short and can reach 4 meters in diameter. Its crown is pyramidal, very dense and dark, with abundant branches and it projects a very dense shade. The leaves, thin and dark green colour, are grouped in spiral on the branch The yew tree has been known since antiquity for its toxicity. It was a sacred tree for the Celts. In ancient times, it was a desired species, particularly for its high quality wood, and was studied both for its medicinal and poisonous properties. It was known as the “tree of death” by the Greeks and Romans and among the ancient Galician, Asturian, Cantabrian and Vasconian populations of the Iberian Peninsula the practice of suicide with yew poison was widespread. It was part of some of their rituals, probably due to the extraordinary longevity of the plant, which makes it seem immortal. For this reason, in many parts of Europe, individual ancient yew trees are considered monuments of nature and, therefore, they are protected and conserved. Currently, yew (Taxus baccata) poisoning is very rare, being of extreme gravity or fatal if it happens. The tree contains a toxic substance called taxine that is dangerous and deadly. It is a mixture of alkaloids that generate gastrointestinal irritation and cardiotoxic effects [2], since it antagonize the sodium and calcium channels in the myocyte causing heart paralysis at high doses. The lethal dose has been estimated at 50-100 grams of leaves, and the twigs and fallen leaves of the tree are as toxic as the fresh plant. Death can occur due to acute cardiotoxicity, although in most cases symptoms usually appear over the course of several hours and even days after exposure [3]. However, as toxins are absorbed quickly, in some cases death occurs by cardiotoxicity so early that no symptoms are manifested.

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