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Poisoning refers to the development of dose-related adverse effects following exposure to chemicals, drugs, or other xenobiotics. To paraphrase Paracelsus, the dose makes the poison. Although most poisons have predictable dose-related effects, individual responses to a given dose may vary because of genetic polymorphism, enzymatic induction or inhibition in the presence of other xenobiotics, or acquired tolerance. Poisoning may be local (e.g., skin, eyes, or lungs) or systemic depending on the route of exposure, the chemical and physical properties of the poison, and its mechanism of action. The severity and reversibility of poisoning also depend on the functional reserve of the individual or target organ, which is influenced by age and preexisting disease.


More than 5 million poison exposures occur in the United States each year. Most are acute, are accidental (unintentional), involve a single agent, occur in the home, result in minor or no toxicity, and involve children <6 years of age. Pharmaceuticals are involved in 47% of exposures and in 84% of serious or fatal poisonings. In the last decade, the rate of injury-related deaths from poisoning has overtaken the rate of deaths related to motor-vehicle crashes in the United States. According to the Centers for Disease Control (CDC), twice as many Americans died from drug overdoses in 2014 compared to 2000. Although prescription opioids have appropriately received attention as a major reason for the increased number of poisoning deaths, the availability of other pharmaceuticals and rapid proliferation of novel drugs of abuse also contribute to the increasing death rate. In many parts of the United States, where these issues are particularly prevalent, there are efforts to develop better prescription drug databases and enhanced training for health care professionals in pain management and the use of opiates. Unintentional exposures can result from the improper use of chemicals at work or play; label misreading; product mislabeling; mistaken identification of unlabeled chemicals; uninformed self-medication; and dosing errors by nurses, pharmacists, physicians, parents, and the elderly. Excluding the recreational use of ethanol, attempted suicide (deliberate self-harm) is the most common reported reason for intentional poisoning. Recreational use of prescribed and over-the-counter drugs for psychotropic or euphoric effects (abuse) or excessive self-dosing (misuse) is increasingly common and may also result in unintentional self-poisoning.

About 20–25% of exposures require bedside health-professional evaluation, and 5% of all exposures require hospitalization. Poisonings account for 5–10% of all ambulance transports, emergency department visits, and intensive care unit admissions. Hospital admissions related to poisoning are also associated with longer lengths of stay and increase the utilization of resources such as radiography and other laboratory services. Up to 30% of psychiatric admissions are prompted by attempted suicide via overdosage. Overall, the mortality rate is low: <1% of all poisoning exposures. It is significantly higher (1–2%) among hospitalized patients with intentional (suicidal) overdose or complications from drugs of abuse, who account for the majority of serious poisonings. Acetaminophen is the pharmaceutical agent most often implicated in fatal poisoning. Overall, carbon monoxide is the leading cause of death from poisoning, but this prominence is not reflected in hospital or poison center statistics because patients with such poisoning are typically dead when discovered and are referred directly to medical examiners.


Although poisoning can mimic other illnesses, the correct diagnosis can usually be established by the history, physical examination, routine and toxicologic laboratory evaluations, and characteristic clinical course.


The history should include the time, route, duration, and circumstances (location, surrounding events, and intent) of exposure; the name and amount of each drug, chemical, or ingredient involved; the time of onset, nature, and severity of symptoms; the time and type of first-aid measures provided; and the medical and psychiatric history.

In many cases the patient is confused, comatose, unaware of an exposure, or unable or unwilling to admit to one. Suspicious circumstances include unexplained sudden illness in a previously healthy person or a group of healthy people; a history of psychiatric problems (particularly depression); recent changes in health, economic status, or social relationships; and onset of illness during work with chemicals or after ingestion of food, drink (especially ethanol), or medications. When patients become ill soon after arriving from a foreign country or being arrested for criminal activity, “body packing” or “body stuffing” (ingesting or concealing illicit drugs in a body cavity) should be suspected. Relevant information may be available from family, friends, paramedics, police, pharmacists, physicians, and employers, who should be questioned regarding the patient’s habits, hobbies, behavioral changes, available medications, and antecedent events. Patients need to be asked explicitly ...

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