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Overview of Poisoning

by Gerald F. O’Malley, DO, Rika O’Malley, MD

Poisoning is the harmful effect that occurs when a toxic substance is swallowed, is inhaled, or comes in contact with the skin, eyes, or mucous membranes, such as those of the mouth or nose.

  • Possible poisonous substances include prescription and over-the-counter drugs, illicit drugs, gases, chemicals, vitamins, food, mushrooms, plants, and animal venom.

  • Some poisons cause no damage, whereas others can cause severe damage or death.

  • The diagnosis is based on symptoms, on information gleaned from the poisoned person and bystanders, and sometimes on blood and urine tests.

  • Drugs should always be kept in original child-proof containers and kept out of the reach of children.

  • Treatment consists of supporting the person, preventing additional absorption of the poison, and sometimes increasing elimination of the poison.

Poisoning is the most common cause of nonfatal accidents in the home. More than 2 million people suffer some type of poisoning each year in the United States. Drugs—prescription, over-the-counter, and illicit—are a common source of serious poisonings and poisoning-related deaths. Other common poisons include gases, household products, agricultural products, plants, industrial chemicals, vitamins, animal venom, and foods (particularly certain species of mushrooms and fish). However, almost any substance ingested in sufficiently large quantities can be toxic.

Young children, because of curiosity and a tendency to explore, are particularly vulnerable to accidental poisoning in the home, as are older people, often due to confusion about their drugs. Also vulnerable to accidental poisoning are hospitalized people (by drug errors) and industrial workers (by exposure to toxic chemicals). Poisoning may also be a deliberate attempt to commit murder or suicide. Most adults who attempt suicide by poisoning take more than one drug and also consume alcohol.

The damage caused by poisoning depends on the poison, the amount taken, and the age and underlying health of the person who takes it. Some poisons are not very potent and cause problems only with prolonged exposure or repeated ingestion of large amounts. Other poisons are so potent that just a drop on the skin can cause severe damage.

Some poisons cause symptoms within seconds, whereas others cause symptoms only after hours or even days. Some poisons cause few obvious symptoms until they have damaged vital organs—such as the kidneys or liver—sometimes permanently.

First Aid

The first priority in helping a poisoned person is for bystanders not to become poisoned themselves. People exposed to a toxic gas should be removed from the source quickly, preferably out into fresh air, but rescue attempts should be done by professionals. Special training and precautions must be considered to avoid being overcome by the toxic gases or chemicals during rescue attempts.

In chemical spills, all contaminated clothing, including socks and shoes, and jewelry should be removed immediately. The skin should be thoroughly washed with soap and water. If the eyes have been exposed, they should be thoroughly flushed with water or saline. Rescuers must be careful to avoid contaminating themselves.

If the person appears very sick, emergency medical assistance (911 in most areas of the United States) should be called. Bystanders should do cardiopulmonary resuscitation (CPR) if needed (see see Cardiac Arrest : First-Aid Treatment). If the person does not appear very sick, bystanders can contact the nearest poison center for advice. In the United States, the local poison center can be reached at 800-222-1222. More information is available at the American Association of Poison Control Centers web site ( ). If the caller knows or can find out the identity of the poison and the amount ingested, treatment can often be initiated at home if this is recommended by the poison center.

Containers of the poisons and all drugs that might have been taken by the poisoned person (including over-the-counter products) should be saved and given to the doctor or rescue personnel. The poison center may recommend giving the poisoned person activated charcoal (see see Poisoning:Prevent absorption of poison) before arrival at a hospital and, rarely, may recommend giving syrup of ipecac to induce vomiting, particularly if the person must travel far to reach the hospital. However, unless specifically instructed to, charcoal and syrup of ipecac should not be given in the home or by first responders (such as ambulance personnel). Syrup of ipecac has unpredictable effects, often causes prolonged vomiting, and may not remove substantial amounts of poison from the stomach.


Identifying the poison is helpful to treatment. Labels on bottles and other information from the person, family members, or coworkers best enable the doctor or the poison center to identify poisons. If labels are not available, drugs can often be identified by the markings and colors on the pill or capsule. Laboratory testing is much less likely to identify the poison, and many drugs and poisons cannot be readily identified or measured by the hospital. Sometimes, urine and blood tests may help in identification as well. Blood tests can sometimes reveal the severity of poisoning, but only with only a very small number of poisons.

For certain poisonings, abdominal x-rays may show the presence and location of the ingested substances. Poisons that may be visible on x-rays include iron, lead, arsenic, other metals, and large packets of cocaine or other illicit drugs swallowed by so-called body packers or drug mules.

Drug testing

Kits can now be bought over the counter that are meant to identify drugs in the urine. The accuracy of these kits can vary significantly. Thus, results should not be regarded as proof that a certain drug has or has not been taken. Testing is best done in consultation with a professional. If done without a professional, results should be discussed with a professional who has experience with drug testing. The professional can help parents interpret test results and draw the appropriate conclusions.


In the United States, widespread use of child-resistant containers with safety caps has greatly reduced the number of poisoning deaths in children younger than age 5. To prevent accidental poisoning, drugs and other potentially dangerous substances should be kept in their original containers. Toxic substances, such as insecticides and cleaning agents, should not be put in drink bottles or cups, even briefly. Other preventive measures include clearly labeling household products, storing drugs and toxic substances in cabinets that are locked and out of the reach of children, and using carbon monoxide detectors. Expired drugs should be disposed by mixing them with cat litter or some other substance that is not tempting and putting them in a trash container that is inaccessible to children. People can also call a local pharmacy for advice on how to properly dispose of drugs. All labels should be read before taking or giving any drugs or using household products.

Limiting the amount of over-the-counter pain relievers in a single container reduces the severity of poisonings, particularly with acetaminophen, aspirin, or ibuprofen. The identifying marks printed on pills and capsules by the drug manufacturer can help prevent confusion and errors by people, pharmacists, and health care practitioners.

Did You Know...

  • In the United States, the local poison center can be reached by dialing 1-800-222-1222.


Some people who have been poisoned must be hospitalized. With prompt medical care, most recover fully.

The principles for the treatment of all poisoning are the same:

  • Support vital functions such as breathing, blood pressure, body temperature, and heart rate

  • Prevent additional absorption

  • Increase elimination of the poison

  • Give specific antidotes (substances that eliminate, inactivate, or counteract the effects of the poison), if available

  • Prevent reexposure

The usual goal of hospital treatment is to keep people alive until the poison disappears or is inactivated by the body. Eventually, most poisons are inactivated by the liver or are passed into the urine.

Supportive care

Poisoning often requires treatment, termed supportive care, to stabilize the heart, blood pressure, and breathing until the poison disappears or is inactivated. For example, a person who becomes very drowsy or comatose may need a breathing tube inserted into the windpipe. The tube is then attached to a ventilator, which mechanically supports the person’s breathing. The tube prevents vomit from entering the lungs, and the ventilator ensures adequate breathing. Treatment also may be needed to control seizures, fever, or vomiting. If a poison causes a high fever, the person may need to be cooled, for example, with a cooling blanket, or sometimes by applying cool water or ice to the skin.

If the kidneys stop working, hemodialysis is necessary. If liver damage is extensive, treatment for liver failure may be necessary. If the liver or kidneys sustain permanent, severe damage, organ transplantation may be needed.

Prevent absorption of poison

Stomach emptying (inducing vomiting or stomach pumping), once commonly done, is now usually avoided because it removes only a small amount of the poison and can cause serious complications. Stomach emptying rarely improves a person's outcome. However, stomach pumping may be done very rarely if an unusually dangerous poison is involved or if the person appears very sick. In this procedure, a tube is inserted through the mouth or nose into the stomach. Water is poured into the stomach through the tube and is then drained out (gastric lavage). This procedure is repeated several times. If people are drowsy because of the poison, doctors usually first put a plastic breathing tube through the mouth into the windpipe (endotracheal intubation). Endotracheal intubation helps keep the gastric lavage liquid from entering the lungs. In the hospital, doctors do not give syrup of ipecac to empty the stomach because its effects are inconsistent.

Activated charcoal is sometimes given in hospital emergency departments to people who have swallowed poisons. Activated charcoal binds to the poison that is still in the digestive tract, preventing its absorption into the blood. Charcoal is usually taken by mouth but may have to be given through a tube that is inserted through the nose into the stomach. Sometimes doctors give charcoal every 4 to 6 hours to help cleanse the body of the poison. Not all poisons are inactivated by charcoal. For example, charcoal does not bind alcohol, iron, or many household chemicals.

Increase elimination of poison

If a poison remains life threatening despite the use of charcoal and antidotes, more complicated treatments that remove the poison may be needed. The most common treatments, hemodialysis and charcoal hemoperfusion, involve filtering poisons directly from the bloodstream. In hemodialysis, an artificial kidney (dialyzer) is used to filter the poisons (see see Hemodialysis). In charcoal hemoperfusion, charcoal is used to help eliminate the poisons. For either of these methods, small tubes (catheters) are inserted into blood vessels, one to drain blood from an artery and another to return blood to a vein. The blood is passed through special filters that remove the toxic substance before being returned to the body.

Whole-bowel irrigation is a treatment method designed to flush a poison from the gastrointestinal tract. It is used only occasionally, for example, for serious poisoning caused by poisons that get stuck in the intestinal tract or need to be moved physically (such as packets of hidden, smuggled drugs) or poisons that are absorbed slowly (such as some sustained-release drugs) or not absorbed by activated charcoal (such as iron and lead).

Sometimes a solution containing sodium bicarbonate (the chemical in baking soda) is given by vein to make the urine more alkaline or basic (as opposed to acidic). This can increase the amount of certain drugs (such as aspirin and barbiturates) excreted in the urine.


Although most poisons and drugs do not have specific antidotes (unlike the popular perception from TV and movies), some do. Some common drugs that might require specific antidotes include acetaminophen (antidote is N -acetylcysteine), aspirin (antidote is sodium bicarbonate), and heroin (antidote is naloxone). Some poisonous bites and stings also have antidotes (see see Snake Bites). Not everyone who has been exposed to a poison requires its antidote. Many people recover on their own. But with severe poisoning, antidotes can be lifesaving.

Common Specific Antidotes




N -Acetylcysteine

Antifreeze (ethylene glycol type)



Benzodiazepines (such as diazepam and lorazepam)


Black widow spider bite

Lactrodectus antivenom


Botulinum antitoxin

Carbamate insecticides (many brands—ingredients should be checked)


Pralidoxime chloride



Cyanide antidote kit (includes amyl nitrate, sodium nitrite, and sodium thiosulfate)

Digitalis, including drugs (digoxin) and plants (oleander, foxglove)

Digoxin-specific antibodies

Heavy metals (such as arsenic, cadmium, lead, mercury, and zinc)

Drugs that remove heavy metals from the body (chelating drugs), such as dimercaprol, edetate calcium disodium, penicillamine, and succimer



Methanol (wood alcohol)



Opioids (such as morphine and heroin)


Organophosphate insecticides (many brands—ingredients should be checked)



Scorpion sting (only the Centruroides species)

Centruroides immune fractionated antibodies

Snakebites* (rattlesnakes and copperheads in the United States)

Rattlesnake (Crotalinae) antivenom




Vitamin K

*Antivenom is specific to the species of snake. There are many antivenoms, but rattlesnakes and copperheads cause most poisonous snakebites in the United States.

Mental health evaluation

People who attempt suicide by poisoning need mental health evaluation and appropriate treatment.

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