What Are the Signs of a Drug or Alcohol Overdose?

Signs and symptoms of a sympathomimetic drug overdose

People who use drugs or alcohol on a regular basis often find that they need to take more and more of the same drug in order to feel the desired effects, such as euphoria, and this is called tolerance.1 Increasing amounts may eventually lead to an overdose. Alcohol or drug overdose can lead to severe mental and physical health consequences and even death.

According to the National Institute on Drug Abuse, more than 70,000 drug overdose deaths occurred in 2017 in the United States. Deaths from fentanyl or fentanyl analogues accounted for nearly 30,000 of those.2

Many overdose deaths may be prevented with quick medical intervention.1 In order to get someone the emergency medical treatment they need, you need to be aware of the signs of an alcohol or drug overdose. While it is important to note that different drugs can produce different overdose symptoms, there are some general indicators that a person is in danger and may be experiencing a potentially life-threatening overdose. If you have any suspicion that someone has overdosed, call for emergency help right away.

Some drugs, such as opioids (heroin and prescription painkillers), benzodiazepines, other sedative-hypnotics, barbiturates and alcohol, may cause life-threatening respiratory depression if a person overdoses on them.3,4,5

Stimulants such as cocaine and prescription stimulants may also be overdosed on, and overdose from these drugs has been associated with heart attacks and seizures.6,7

If you suspect an individual has overdosed, do not hesitate to call 911. Every second counts when it comes to saving someone’s life.

Possible Signs of Overdose

  • Unconsciousness
  • Breathing changes
  • Body temperature changes
  • Vomiting
  • Rapid, slow, or irregular heartbeat
  • Chest pain
  • Anxiety/agitation/confusion
  • Seizures
  • Hallucinations

Intervening early in an overdose can save a person’s life, but you must know what to look for. These are some signs that could indicate that a person is suffering from an overdose:

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  • In some cases, a person experiencing an overdose will seem to be asleep.3 This can occur in overdoses from drugs that slow the central nervous system, such as opioids, benzodiazepines, barbiturates, other sedative-hypnotics, and alcohol.3,4,5,8 In the case of alcohol overdose, a person who is passed out may be left by friends to “sleep it off,”; however, this can be extremely dangerous as alcohol levels may continue to rise even after drinking has stopped, and without help, the person may suffer lasting brain damage, may choke on their own vomit, and may die.5

Breathing Changes

  • Normally, people breathe in and breathe out in a regular rhythm. According to Johns Hopkins Medicine, normal breathing rates range from 12 breaths to 16 breaths per minute in an adult at rest. Someone in the midst of an overdose from a drug like heroin, alcohol, or prescription CNS depressants may breathe much slower than this, breathe irregularly, or stop breathing altogether.3,4,5 Overdosing on drugs like cocaine or prescription stimulants may lead to breathing rapidly or trouble breathing.6, 7

Body Temperature Changes

  • The U.S. National Library of Medicine suggests that normal body temperatures can range from about 97 to 99 degrees Fahrenheit.There is some variability to be expected from one body to another, but a person in the middle of an overdose may feel cold or clammy. The skin, lips, and nails might appear blue, which is a major warning sign that the person is in danger. This may occur in the case of opioid overdose, alcohol overdose, or other overdoses.5,10 Increased temperatures may indicate overdose from stimulants such as cocaine or prescription stimulants.6, 7


  • Vomiting can help expel a toxic substance from the gastrointestinal system, so while it feels bad, it can serve an important purpose.11 Unfortunately, people suffering from an overdose can, and sometimes do, vomit while they are not awake. That could lead to choking on their own vomit, which could lead to very serious consequences, including brain damage or death.5

Rapid, Slow, or Irregular Heartbeat

  • Different drugs impact the heart in different ways. For example, stimulant drugs can cause the heart to race or an irregular heartbeat.7 On the other hand, people who take opioids such as heroin or morphine or drink too much might have a dangerously slowed heart rate or irregular heart rhythm.5,12 You can most easily check a person’s pulse on their wrist or neck. A normal adult resting rate is between 60 and 100 beats per minute.13

Chest Pain

  •  Stimulant overdose may result in chest pain, palpitations, and even heart attack or stroke.6,14

Anxiety, Agitation, or Confusion


  • Overdose from certain drugs such as stimulants and alcohol are associated with seizure risk.5,14 If someone is experiencing a seizure, call 911 and stay with the person until medical personnel arrive.


  • Overdose from drugs like stimulants or cannabis may result in the onset of hallucinations,15 in which a person sees, hears, smells, or feels things that aren’t there. Hallucinations may lead to injuries resulting from accidents or self-harm. If you suspect that someone is hallucinating from an overdose, call 911 right away.

If someone is showing signs of an alcohol overdose than call 911 for help

An overdose is considered a life-threatening emergency. These are not all the possible signs of an overdose, and signs can vary. If you at all suspect someone has overdosed, call 911 for help and follow the instructions of the operator. If you know which drugs the person has taken, relay that information to the operator.10 However, it is not necessary that you have this information to call. The operator may ask you about the overdosing individual’s symptoms and guide you in steps to take (e.g., laying the person on their side, beginning CPR, etc.) as you wait for the ambulance to arrive.5,16

When the crisis has passed, it may be a good time to attempt to bring up the issue of getting help. You can direct the person to resources that can help them if they are struggling with a drug or alcohol addiction. The overdose could be the wakeup call that person needs to recover.

Additional Articles of Interest


  1. National Institute on Drug Abuse. (2007). The Neurobiology of Drug Addiction: 6: Definition of tolerance.
  2. National Institute on Drug Abuse. (2019). Overdose Death Rates.
  3. World Health Organization. (2018). Information sheet on opioid overdose.
  4. National Institute on Drug Abuse. (2018). What are prescription CNS depressants?
  5. National Institute on Alcohol Abuse and Alcoholism. (2018). Understanding the Dangers of Alcohol Overdose.
  6. National Institute on Drug Abuse. (2018). What is cocaine?.
  7. National Institute on Drug Abuse. (2018). Prescription Stimulants.
  8. Community Management of Opioid Overdose. Geneva: World Health Organization; 2014. GLOSSARY OF TERMS USED IN THESE GUIDELINES.
  9. U.S. National Library of Medicine. (2019). Body temperature norms.
  10. Drug Enforcement Administration. (n.d). What Should You Do in an Overdose Situation?
  11. Horn C. C. (2007). Why is the neurobiology of nausea and vomiting so important?Appetite50(2-3), 430–434.
  12. Ghuran, A., & Nolan, J. (2000). The cardiac complications of recreational drug useThe Western journal of medicine173(6), 412–415.
  13. NHS. (2018). How do I check someone’s pulse?.
  14. Substance Abuse and Mental Health Services Administration. (1999). Chapter 5—Medical Aspects of Stimulant Use Disorders, Treatment for Stimulant Use Disorders.
  15. NHS. (2018). Poisoning symptoms.
  16. National 911 Program. (n.d.). Frequently Asked Questions.
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