Heroin Intoxication – Symptoms and Emergency Treatment

What Is Heroin Intoxication?

Heroin intoxication refers to the acute poisoning of the body caused by an overdose of the illegal opioid drug heroin (chemically known as diacetylmorphine). Heroin acts as a powerful depressant of the central nervous system and can cause life-threatening respiratory depression even in small doses. Heroin intoxication is a medical emergency and one of the leading causes of drug-related deaths worldwide.

Causes and Risk Factors

Heroin intoxication occurs when the amount of heroin consumed exceeds the individual tolerance threshold of the body. Several factors increase the risk of overdose:

• Interruption of use (e.g., after release from prison, hospitalization, or completing a treatment program), as tolerance has decreased
• Unknown purity or potency of the heroin – the active content on the black market varies considerably
• Mixing heroin with other depressant substances such as alcohol, benzodiazepines, or other opioids
• Intravenous injection, which delivers a particularly rapid and intense effect
• Pre-existing conditions affecting the lungs, liver, or heart
• Exhaustion, malnutrition, or a generally weakened physical state

Symptoms

The clinical presentation of heroin intoxication is characteristic and is often referred to as the opioid toxidrome. Typical symptoms include:

• Respiratory depression: Slow, shallow, or absent breathing – the most common cause of death
• Miosis: Severely constricted pupils (pinpoint pupils), even in dim lighting
• Loss of consciousness or deep sedation: The affected person is barely or completely unresponsive
• Cyanosis: Bluish discoloration of the lips and fingernails due to oxygen deprivation
• Bradycardia: Slow heart rate
• Hypotension: Low blood pressure
• Muscle limpness (skeletal muscle hypotonia)
• Gurgling or rattling breathing sounds
• Foam at the mouth, indicating aspiration or pulmonary edema

The classic triad of opioid poisoning consists of: respiratory depression, unconsciousness, and miosis.

Diagnosis

The diagnosis of heroin intoxication is primarily made clinically in the emergency setting – meaning it is based on symptoms and medical history. The following diagnostic measures are used:

• Clinical examination: Assessment of respiratory rate, level of consciousness, pupil size, and skin color
• Pulse oximetry: Measurement of blood oxygen saturation
• Arterial blood gas analysis (ABG): Detection of respiratory acidosis due to elevated CO2
• Urine drug screening: Detection of opiates in the urine (heroin is rapidly metabolized to morphine)
• Serum toxicology: Detailed blood analysis when available
• ECG: Assessment of cardiac arrhythmias

The response to naloxone (opioid antagonist) administration also serves as a diagnostic criterion: rapid symptom improvement after naloxone confirms opioid intoxication.

Treatment

Immediate Measures

If heroin intoxication is suspected, emergency services (911 or the local emergency number) must be called immediately. Until help arrives, the following first aid measures apply:

• Place the person in the recovery position if they are breathing but unconscious
• Check and secure the airway
• Begin cardiopulmonary resuscitation (CPR) if breathing or circulation has stopped

Emergency Pharmacological Treatment

The most important antidote is naloxone (brand names: Narcan, Kloxxado). It is a pure opioid antagonist that immediately reverses the effects of heroin at the opioid receptor. Naloxone can be administered intravenously, intramuscularly, subcutaneously, or as a nasal spray. Since the duration of action of naloxone (30–90 minutes) is shorter than that of heroin, repeat doses are often necessary. In some countries, naloxone is available as a take-home antidote for at-risk individuals and their families.

Intensive Care Measures

• Airway management through intubation and mechanical ventilation in cases of severe respiratory depression
• Intravenous fluid administration to stabilize circulation
• Monitoring in an intensive care unit
• Treatment of complications such as aspiration pneumonia or pulmonary edema

Complications

Untreated or severe heroin intoxication can result in permanent damage or death. Possible complications include:

• Hypoxic brain damage due to prolonged oxygen deprivation
• Aspiration pneumonia from inhaling vomit
• Non-cardiogenic pulmonary edema
• Rhabdomyolysis (muscle cell breakdown) and acute kidney failure
• Cardiac arrhythmias and cardiac arrest

Prevention and Harm Reduction

Prevention strategies to reduce heroin-related deaths include:

• Naloxone availability: Wider distribution of naloxone to at-risk individuals and their social networks
• Drug consumption rooms: Supervised facilities where drug use can take place under medical oversight
• Opioid substitution therapy (OST): Treatment with methadone or buprenorphine to reduce heroin use
• Education about risks following periods of abstinence
• Low-threshold access to addiction counseling and treatment programs

References

1. World Health Organization (WHO): Information sheet on opioid overdose. Geneva, 2014. Available at: https://www.who.int/substance_abuse/information-sheet/en/
2. European Monitoring Centre for Drugs and Drug Addiction (EMCDDA): Preventing overdose deaths in Europe. Lisbon, 2020.
3. Schiller EY, Goyal A, Mechanic OJ: Opioid Overdose. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing, 2023. Available at: https://www.ncbi.nlm.nih.gov/books/NBK470415/