OTC Overdose


Over-the-counter (OTC) drug abuse is on the rise. Since 2000 there has been a fourfold increase in abuse of cold medicine. Nonsteroidal anti-inflammatory drugs (NSAIDS) are the third most commonly intentionally overdosed medicine. Acetaminophen overdose is responsible for the greatest number of drug overdose hospital admissions in developed countries. Hundreds of different nonprescription medicines are available. This article discusses assessment and treatment considerations for overdoses of four of the most commonly abused OTC drugs.






A nervous mother calls you for her son, who recently broke his leg. Your 16-year-old patient is lying on the couch, complaining of severe right upper quadrant pain that has been worsening for the past two days. His mother tells you he has been vomiting frequently for “a while.” A physical exam reveals abdominal tenderness and no signs of problems with the broken leg. The patient’s heart rate is 112, blood pressure 94/60 and respiratory rate 28. The boy tells you he has been taking acetaminophen for his leg pain. A bottle of 500-mg pills on the coffee table is nearly empty. Based upon your exam and history findings, you suspect an accidental acetaminophen overdose.

Acetaminophen (Paracetamol)is a non-narcotic pain medication used by millions of people each year. It is the most common adult analgesic and most common pediatric medication. Adults can safely ingest up to 4 grams of acetaminophen a day; pediatrics can ingest 90 mg/kg. Consumption of 150 mg/kg per day or more is toxic and considered an overdose. Acetaminophen overdose is the leading cause of acute liver failure in North America.

After ingestion, acetaminophen is quickly absorbed through the stomach directly into the bloodstream. Once there it can only be metabolized into waste by the liver. The kidneys can only excrete acetaminophen after it is metabolized in the liver. Acetaminophen overdose saturates the liver’s normal metabolic pathways and prevents effective function. As a result, a toxic metabolite forms, which binds with proteins in the liver, resulting in cellular death, which eventually leads to liver necrosis.

Patients with acetaminophen toxicity go through four phases. Phase 1 occurs during the first 24 hours following ingestion. During this time the patient may be asymptomatic, but may also have loss of appetite, malaise, diaphoresis, pallor and complain of nausea and vomiting.

Phase 2 occurs 18-72 hours after ingestion. During this time, patients often complain of right upper quadrant pain with tenderness upon palpation. Nausea, vomiting and appetite loss worsen. Patients may also present with tachycardia and hypotension.

Acetaminophen toxicity fatalities triggered by cerebral edema, sepsis or multi-organ failure usually occur during phase 3. Fortunately, fewer than 4% of overdoses are fatal. Patients in phase 3 develop jaundice and severe tenderness around the liver, often have difficulty clotting blood and can develop internal bleeding. Lab testing may reveal evidence of hepatic encephalopathy, renal failure, hypoglycemia and acidosis.

Patients who survive the first four days and three phases enter phase 4. Over several weeks symptoms slowly subside. Organ failure is managed while the body heals. Just less than half of severe acetaminophen overdoses require liver transplants during phase 4. Fortunately, most patients’ symptoms are completely resolved in roughly three weeks.


You receive a midmorning call for a child with an altered mental state. The patient’s mother tells you her 8-year-old son stayed home from school because his allergies were making him sick. Although he’s been taking Benadryl, he seems to be getting worse. The boy began complaining of blurred vision 15 minutes ago. He is confused and resists help. His skin is very hot and dry to the touch, and you notice a half-empty box of Benadryl on the floor nearby. You start supplemental oxygen and obtain vitals: pulse 142, BP 86/62, respirations 28 and shallow. The child has accidentally overdosed on his antihistamine.

Histamines are released into the bloodstream after exposure to an allergen. Antihistamines counter their effects by blocking histamine receptors in the body. Antihistamines can be either sedative or nonsedative. They normally reduce bronchospasm, vasodilation and edema caused by histamine release. The maximum safe antihistamine dose differs from brand to brand. Overdoses are identified through symptom recognition. Brand-dependent differences in dose sizes often cause accidental overdoses.

Normally antihistamines have a 10-hour half-life. However, in cases of toxicity, half-life doubles, keeping the drug in the system longer. Antihistamine overdose symptoms develop 30-120 minutes after ingestion.

The mnemonic Dry as a bone, red as a beet, hot as a hare, mad as a hatter, and blind as a bat is a tool to remember the symptoms of antihistamine overdose. Mucous membranes dry up, and the skin becomes hot, dry and flushed. Vasodilation leads to hypotension and tachycardia. Pupils dilate, and vision becomes blurred. Mental status changes include hallucinations, agitation, disorientation, lethargy and, in rare cases, coma. Seizures are uncommon and, when they do occur, short in duration. Sedative antihistamine overdoses also present with delirium and sedation. Antihistamine overdose patients frequently have dangerous ECG abnormalities. Tachycardias are common, as well as lengthened QT intervals. Nonsedative antihistamine overdoses can cause torsade de pointes.


A 23-year-old male is complaining of nausea and vomiting. He presents lying anxiously on the couch, guarding his stomach. His girlfriend says he took several bottles of ibuprofen. Your partner estimates there were 30 grams of ibuprofen in the two now-empty bottles. The exam is unremarkable except for hypotension and tachycardia. The patient is treated for ibuprofen overdose, including intubation and ICU care after developing metabolic acidosis, renal failure and adult respiratory distress syndrome.

Over 10% of all medical patients in the U.S. are on some form of nonsteroidal anti-inflammatory drugs (NSAIDs). Annually, more than 103,000 people are hospitalized and 16,500 die from NSAID complications, including overdose. Average-size adults can safely consume up to 100 mg/kg of a single NSAID in one day; toxicity begins as patients pass this threshold. Ingestion of more than 400 mg/kg often leads to life-threatening conditions.

NSAID overdoses can cause renal failure and lead to intestinal and stomach ulcers. Manifestations of overdose develop 4-48 hours after ingestion. Complaints include headache, tinnitus (ringing in the ears), deafness, nausea and abdominal pain. Physical exam may reveal diaphoresis, rashes, pulmonary edema, convulsions and hypertension, which develops as a result of water retention.

Mental status is a good measure of NSAID overdose severity. Minor overdoses cause changes such as anxiety, confusion and disorientation. Patients with major overdoses can become delirious and have decreased levels of consciousness. Expect dysrhythmias such as tachycardias and bradycardias. Patients sensitive to aspirin who overdose on NSAIDs may go into respiratory arrest. Within days of ingestion, patients can develop adult respiratory distress syndrome, metabolic acidosis and renal failure.


At Elmbrook Middle School, a 13-year-old is seizing. Upon arrival, your patient is responding to painful stimuli in care of the school nurse, who says she seized for three minutes. The girl has no history of seizures, takes no prescription medicines and has no allergies. The nurse says she had been acting strangely in class, as if she were drunk; however, she does not smell like alcohol. Physical exam reveals constricted pupils, diaphoresis and moaning upon palpation of the abdomen. While examining the patient you find a box of cold medicine capsules in her pocket. You suspect the child has overdosed on dextromethorphan, a drug in cold and cough medications.

More than 140 common cold and cough medicines contain dextromethorphan, a synthetic non-narcotic chemical commonly known as DXM. The normal recommended dose of DXM is 15-30 mg. DXM is absorbed through the stomach lining into the bloodstream, eventually raising the coughing threshold in the brain. Since DXM acts directly on the brain, it affects mental status. DXM comes in many forms: liquid, capsules, tablets, gel caps and lozenges. Capsules and tablets are the most potent and frequently abused. Abusers seek DXM because of the effects it provides, which are similar to those of PCP and ketamine. The amount ingested is dictated by the desired effects of use, which occur on four plateaus. Generally, users must take at least 100 mg for minimal effect, but many abusers often take more than 200 mg at a time.

When a patient has consumed between 1.5-2.5 mg/kg, they enter the first plateau. They experience a sensation of alertness and restlessness, and feel intense emotions and general euphoria. This patient may have loss of balance and appear intoxicated. Additionally, their pulse and core body temperature may become elevated.

Ingesting 2.5-7.5 mg/kg puts patients at the second plateau. These patients present with slurred speech, motor impairment, emotional detachment and short-term memory loss. Abusers may complain of hallucinations and strobe light vision. Some describe this plateau as being in a dreamlike state, detached from the outside world or heavily “stoned.”

Significant body toxicity begins at the third plateau, ingestion of 7.5-15 mg/kg. Patients present with an obviously altered level of consciousness and may not be able to comprehend what is said. They complain of disrupted sound and vision, have trouble recognizing people or known objects, and have abstract thoughts. Some feel emotionally detached and complain of out-of-body experiences.

Consumption of more than 15 mg/kg puts patients on the fourth plateau. Nervous system disruption denies the brain of normal sensory input and may cause temporary blindness. Rapid heart rates are common. Patients experience signs of severe overdose: lifelike hallucinations, major delusions, recall of buried memories, feelings of out-of-body separation, etc.

Medications contain varying concentrations of DXM; thus the amount required for overdose varies. For example, 4 oz. of Robitussin, or half a bottle, can cause a DXM overdose. Symptoms include blurred vision, dry mouth, delusions, nausea and vomiting, numbness in the fingers and toes, headaches, diaphoresis, abdominal tenderness, and dry, itchy skin. Other signs include extremely irregular heartbeat, hypotension, shallow respirations and a decreased level of consciousness.

Patients with critically high toxic levels of DXM may experience uncontrolled violence, severe psychosis, seizures or coma. Toxic DXM levels, especially if mixed with other drugs or alcohol, can lead to death.

Additional problems occur when cold medicines contain multiple drugs. For example, overdosing on a medicine with DXM and antihistamines could cause a synergistic decrease in respirations and lead to respiratory arrest.


Scene size-up is very important on suspected overdose calls. Be sure the scene is safe. Overdose patients who are hallucinating or in a psychotic state can be aggressive and violent. Keep yourself and your coworkers safe. If necessary, wait for the police before entering. When approaching the scene and patient, keep in mind that in addition to the medical emergency, the patient may also be having a psychological emergency. Many suicidal patients choose a slow but potentially lethal combination of OTC drugs, alcohol and street drugs.

OTC drug overdoses can compromise critical systems. Begin by assessing the ABCs. Ensure patients have a patent and secured airway, and be prepared to suction vomit. Provide supplemental oxygen, and assist ventilations if needed. Check the adequacy of circulation and, if indicated, start an IV and begin cardiac monitoring.

A thorough and accurate history is critical to proper patient care. Information obtained in the field affects in-hospital treatment. Be a detective—spend a few extra minutes getting all the information you can from the patient, bystanders and other scene clues. Try to find out what was ingested, when and how much. Find out if the patient has vomited. If so, how often and how much? Try to determine if the overdose was accidental or intentional. Overdose patients are often unreliable historians.

Pay attention to scene clues around the patient and in the immediate area. Look for medication containers or spilled drugs and medications. Collect any medicines you find and bring them with the patient to the hospital. Interviewing witnesses may provide information critical to proper care. Often the person who called you knows exactly what happened. Separating the reporting party from the patient relieves the witness’ anxiety about revealing the truth, and they often will detail what led to the overdose.

Intentional OTC drug overdoses are a manifestation of psychological distress. Unfortunately, these patients may reject your assistance. When treating an intentional overdose, it is important to show you care by providing compassionate care. Establish a trust with the patient by listening to their answers to your questions and being honest.

A complete assessment includes a thorough SAMPLE history and physical examination. Physical signs reveal important clues to your patient’s condition. For example, pupils constrict during DXM overdoses and dilate from antihistamines. Remember to listen to lung sounds and check for any abdominal tenderness. Investigate pain using the OPQRST mnemonic. Monitor vitals frequently. Note any changes and look for trends. Hypotension may occur very quickly.


The primary goal of field treatment for OTC overdoses is to protect and maintain the airway, breathing and circulation. Manage any life-threatening conditions immediately. Effective treatment starts with airway management. Deliver supplemental oxygen to all potential overdose patients. Many OTC overdose patients are prone to vomiting because medications contain multiple drugs. Watch for vomiting and be ready to suction. Place patients with decreased levels of consciousness in the left lateral recumbent position and consider inserting a nasal pharyngeal airway to improve air exchange. If necessary, ventilate with a bag-valve mask.

Monitor patients carefully. Patients who overdose on sedative-based medications often experience rapid decreases in respiratory rate and depth. Be prepared to secure the airway with intubation, a Combitube or another non-visualized airway device. Keep in mind, however, that because the patient is at high risk for vomiting, use only airway devices that isolate the trachea from the esophagus. Do not use an airway that could cause aspiration.


The purpose of activated charcoal is to neutralize the toxin by absorbing it in the stomach and intestinal tract. Once absorbed, the toxin cannot enter the bloodstream. Since it is impossible for activated charcoal to absorb toxins already in the bloodstream, early administration is key. Consider administering activated charcoal, especially within one hour of ingestion. Activated charcoal can significantly decrease the effects of overdose up to four hours after ingestion when patients have taken antihistamines or NSAIDs. Give patients 1 g/kg by mouth. The dosage is the same for both adults and pediatrics. Because activated charcoal is an oral medication, it is contraindicated in patients with decreased levels of consciousness.


You may run across families at home who still have syrup of ipecac. Administration of this, designed to induce vomiting, is unacceptable. Do not administer syrup of ipecac to any patient, and encourage anyone you encounter with the medication to dispose of it properly.


Initiate IV access on all overdose patients and provide a fluid bolus if patients are hypotensive. Check the blood sugar level of any patient with altered mental state or a decreased level of consciousness. Patients who have seized are often hypoglycemic.

Consider naloxone if you suspect polydrug use involving narcotics and the patient has a decreased respiratory rate. Follow local protocols to administer a benzodiazepine such as midazolam or diazepam to patients who begin to seize. Patients who are hostile or combative may require chemical sedation. Administering a sedative such as lorazepam may not only be prudent for your safety, but also for proper medical care.

Provide EKG monitoring for all overdose patients. Monitor for both tachy- and bradycardias. Patients who have taken antihistamines may have lengthened QT intervals or spontaneously go into torsade de pointes. If conscious, torsade de pointes patients often complain about palpitations.


If local protocols permit, consider placing a nasogastric tube. Emergency departments often perform gastric lavage on overdose patients who arrive within one hour of ingestion. This reinforces the importance of on-scene assessment and an accurate transport priority determination. While gastric lavage has no benefit when patients have ingested acetaminophen, early placement will not hurt the patient, and may help.

Any time you suspect an OTC overdose, transport to the hospital is required. Often there are antidotes available in the emergency department, and the ability to administer them depends on your ability to recognize both the kind and severity of the overdose, and provide safe and rapid transport.

During transport, monitor and support ABCs, reassess vital signs and continue to gather patient history. Advise the ED staff of any changes in the patient’s condition during transport.


Occasionally we are called to a potential overdose where the patient appears fine and refuses transport. However, OTC overdose patients need a physician evaluation, even when they appear asymptomatic. An intentional overdose is an attempt to self-harm and a threat to personal well-being. Anyone who poses a potential threat to themselves or others cannot sign a patient refusal. Patients, who have potentially overdosed on anything, including over-the-counter medications, can be placed in protective custody by the police. Utilize police assistance if necessary to ensure patients are transported to the hospital.

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