An overdose is the accidental or intentional use of a drug or medicine in an amount that is higher than normally used or prescribed.
All drugs have the potential to be misused, whether legally prescribed by a doctor, purchased over the counter at the local drug store, or bought illegally on the street. Taken in combination with other drugs or with alcohol, even drugs normally considered safe do cause death or serious long-term consequences. Children are particularly at risk for accidental overdose, accounting for more than one million poisonings each year from drugs, alcohol, and other chemicals and toxic substances. People who suffer from depression and who have suicidal thoughts are also at high risk for drug overdose.
Causes and symptoms
Accidental drug overdose may be the result of the misuse of prescription medicines or commonly used medications such as pain relievers and cold remedies. Symptoms differ depending on the drug taken. Some of the drugs commonly involved in overdoses are listed below along with symptoms and outcomes.
Acetaminophen is the generic name for the commonly used pain reliever Tylenol. An overdose of this drug can cause liver damage with symptoms that include loss of appetite, tiredness, nausea and vomiting, paleness, and sweating. The next stage of symptoms indicates liver failure and includes abdominal pain and tenderness, swelling of the liver, and abnormal blood tests for liver enzymes. In the last stage of this poisoning, liver failure advances and patients become jaundiced, with yellowing of the skin and whites of the eyes. They may also experience kidney failure, bleeding disorders, and encephalopathy (swelling of the brain).
Salicylates are found in aspirin and some creams or ointments used for muscle and joint pain such as Ben-Gay and for psoriasis, a skin condition. Initial symptoms are gastrointestinal irritation, fever, and vomiting, possibly with blood in the vomit. An overdose of salicylates will cause metabolic acidosis and respiratory alkalosis, conditions in which the body's pH (acid/base balance) malfunctions. Symptoms include rapid heart beat and fast breathing. Nervous system symptoms include confusion, hallucinations, tiredness, and ringing in the ears. An increased tendency to bleed is also common. Serious
Anticholinergic drugs that block the action of acetylcholine, a neurotransmitter include atropine, scopolamine, belladonna, antihistamines, and antipsychotic agents. They cause the skin and moist tissues such as in the mouth and nose to become dry and flushed. Dilated pupils, an inability to urinate, and mental disturbances are also symptoms. Severe toxicity can lead to seizures, abnormal heart rhythms, extremely high blood pressure, and coma.
Cholinergic drugs that stimulate the parasympathetic nervous system, such as carbamate and pilocarpine, cause nausea, diarrhea, increased secretion of body fluids such as sweat, tears, saliva, and urine, fatigue, and muscle weakness. Convulsions are possible. Death can occur due to respiratory failure and heart failure.
Antidepressant drugs such as amitriptyline, desipramine, and nortriptyline can cause irregular heart rate, vomiting, low blood pressure (hypotension), confusion, and seizures. An overdose of antidepressants also causes symptoms similar to those seen with anticholinergic drug overdoses.
Depressant drugs such as tranquilizers, antianxiety drugs, and sleeping pills cause sleepiness, slowed or slurred speech, difficulty walking or standing, blurred vision, impaired ability to think, disorientation, and mood changes. Overdose symptoms can include slowed breathing, very low blood pressure, stupor, coma, shock, and death.
Cocaine and crack cocaine overdoses cause seizures, high blood pressure, increased heart rate, paranoia, and other changes in behavior. Heart attack or stroke are serious risks within three days after cocaine overdose.
Heroin, morphine, and codeine are narcotic or opiate drugs. Clonidine and diphenoxylate (Lomotil) are also in this category. Overdose with opiate drugs causes sedation (sleepiness), low blood pressure, slowed heart rate, and slowed breathing. Pinpoint pupils, where the black centers of the eyes become smaller than normal, are common in opiate overdose. However, if other drugs are taken at the same time as the opiates, they may counteract this effect on the pupils. A serious risk is that the patient will stop breathing (respiratory arrest).
Digoxin, a drug used to regulate the heart, can cause irregular heartbeats, nausea, confusion, loss of appetite, and blurred vision.
Diagnosis of a drug overdose may be based on the symptoms that develop; however, the drug may do extensive damage to the body before significant symptoms develop. If the patient is conscious, the physician may be able to find out what drugs were taken and in what amounts. The patient's recent medical and social history may also help in a diagnosis. Information such as a list of medications that the patient takes, whether or not alcohol was consumed recently, or whether the patient had eaten in the last few hours can be valuable in determining how fast the overdosed drug will be absorbed into the system.
Different drugs have varying effects on the body's pH and on certain elements in the blood such as potassium and calcium. Blood tests can be used to detect changes in body chemistry that may give as clues to what drugs were taken. Blood can also be screened for various drugs in the system. Once the overdose drug is identified, blood tests can be used to monitor how fast the drug is being cleared out of the body. Urine tests are another way to screen for some drugs and to detect changes in the body's chemistry. Blood and urine tests may show if there is damage to the liver or kidneys as a result of the overdose.
If a drug overdose is discovered or suspected, and the person is unconscious, having convulsions, or not breathing, emergency help must be called immediately. If the person who took the drug is not having symptoms, it is recommended not to wait to see if symptoms develop, but to call a poison control center immediately. Providing as much information as possible to the poison control center can help determine what the next course of action should be.
The poison control center, paramedics, and emergency room staff will want to know the following:
- what drug(s) were taken
- how much of the drug was taken
- when was the drug taken
- if the drug was taken with alcohol or any other drugs or chemicals
- what the age of the patient is
- what symptoms the patient is experiencing
- if the patient is conscious
- if the patient is breathing
Hypotension—Having a low blood pressure: less than 90/60 mmHg.
Intubation—A procedure in which a tube is inserted through the mouth or nose and into the trachea to keep the airway open and to help the patient breathe.
The poison control center may recommend a liquid called ipecac syrup, which is used to induce vomiting. Ipecac syrup is an over-the-counter medication available from pharmacies, and no prescription is required. Pediatricians may advise families to keep ipecac syrup on hand in households with children. This medication should be used only on the advice of a medical professional. An important caveat is that vomiting should not be induced if the patient is unconscious as there is serious risk of choking.
Emergency medical treatment may include:
- Assessment of the patient's airway and breathing to make sure that the trachea, the passage to the lungs, is not blocked. If needed, a tube may be inserted through the mouth or nose and into the trachea to help the patient breathe. This procedure is called endotracheal (in the trachea) intubation.
- Assessment of the patient's vital signs, including heart rate, blood pressure, body temperature, respiratory rate, and other physical signs that might indicate the effects of the drug.
- Blood and urine samples may be collected to test for the presence of the suspected overdose drug, and other drugs or alcohol that might be present.
- Attempt to eliminate the whatever of the drug that has not yet been absorbed. Vomiting may be induced using ipecac syrup or other drugs that cause vomiting. Ipecac syrup should not be given to patients who overdosed with tricyclic antidepressants, theophylline, or any drug that causes a significant change in mental status.
- Gastric lavage, also known as pumping the stomach, may be attempted. For this procedure, a large flexible tube is inserted through the nose or mouth, down the throat, and into the stomach. The contents of the stomach are then suctioned out through the tube. A solution of saline (salt water) or regular tap water is pushed down into the tube to rinse out the stomach. The saline solution or water is then suctioned out. This process is repeated several times until the suctioned fluid is clear.
- Activated charcoal to absorb the drug is sometimes given through a stomach tube or by having the patient swallow it.
- Medication to stimulate urination or defecation may be given to try to flush the excess drug out of the body faster.
- Intravenous (IV) fluids may be given. An intravenous line, a needle inserted into a vein, may be put into the arm or back of the hand. Fluids, either sterile saline (salt water solution) or dextrose (sugar water solution), can be administered through this line. Increasing fluids can help to flush the drug out of the system and to reestablish balance of fluids and minerals in the body. The pH of the body may need to be corrected by administering electrolytes such as sodium, potassium, and bicarbonate through the IV line. If drugs need to be administered quickly, they can also be injected directly into the IV line.
- Hemodialysis is a procedure in which blood is circulated out of the body, pumped through a dialysis machine, then reintroduced back into the body. This process can be used to filter some drugs out of the blood and can clean the blood. It may also be used temporarily or long term if the kidneys are damaged due to the overdose.
- Antidotes that are available for some drug overdoses may be administered. An antidote is another drug that counteracts or blocks the overdose drug.
- Psychiatric evaluation is performed if the drug overdose was taken deliberately. If the overdose is determined to be a deliberate act, further psychiatric care is provided while the patient is hospitalized.
While many victims of drug overdose recover without long-term effects, there can be serious consequences. Some drug overdoses cause the failure of major organs like the kidneys or liver, or failure of whole systems like the respiratory or circulatory systems. Patients who survive drug overdose may need kidney dialysis, kidney or liver transplant, or ongoing care as a result of heart failure, stroke, or coma. Death can occur in almost any drug overdose situation, especially if treatment is not started immediately.
Health care team roles
Nurses play a vital role in helping victims of drug overdoses. The emergency room nurses perform the gastric lavage procedure on the patient who has overdosed, as well as administrating antidotes or other medications ordered by the doctor. Nurses are responsible for monitoring the patient and recording important assessment findings. Nurses should be cognizant of the importance of careful monitoring of drug levels.
Another important assessment done by the nurse, either in the emergency room or on the psychiatric unit, is the evaluation of patient support systems. A deliberate overdose can be a devastating event for the entire family, and the nurse can help foster communication between the patient and family members. When a family tries to minimize the intentional overdose, the nurse must strongly emphasize that any suicidal threat or act ought to be regarded as critical.
To protect children from accidental drug overdose, all medications should be stored in containers with child-resistant caps. All drugs should be out of sight and out of reach of children, preferably in a locked cabinet. The person to whom medication is prescribed should take it according to the directions. Threats of suicide need to be taken seriously, and appropriate help sought for people with depression or other mental illness that may lead to suicide.
Haddad, Lester M. Clinical Management of Poisoning and Drug Overdose, 3rd ed. Philadelphia: W. B. Saunders, 1998.
Borowsky, I. W. "Adolescent Suicide Attempts: Risks and Protectors." Pediatrics 107 (2001): 485-93.
Anker, Anthony. Drug Overdose from AAEM Emergency Medical and Family Health Guide/Poisioning. <http://www.emedicine.com/aaem/topic169.htm>.
Graber, Mark A. "Emergency Medicine: Overdose and Toxindromes." University of Iowa Family Practice Handbook, 3rd ed. <http://www.vh.org/Providers/ClinRef/FPHandbook/Chapter01/20-1.htm>.
"Poisoning." The Merck Manual of Diagnosis and Therapy, 17th ed. <http://www.merck.com/pubs/mmanual/section23/chapter307/307a.htm>.
"Poisoning." The Merck Manual Home Edition. <http://www.merck.com/pubs/mmanual_home/sec24/286.htm>.
"Suicidal Behavior." The Merck Manual Home Edition. <http://www.merck.com/pubs/mmanual_home/sec7/85.htm>.