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Drug overdose: definition, causes, and risks

Reading time: 8 mins

Drug overdose is a potentially dangerous complication indicated by an excessively high intake of drugs in a short period of time. The term drug overdose doesn’t just refer to cocaine, heroin, methamphetamine, and similar substances. People can also overdose on alcohol and prescription opioids. 

The cause of drug overdose, which can be intentional or accidental, is overstimulation of the brain and body. As a person takes too much of the drug, their brain, and body go into overdrive, which causes a wide range of overdose symptoms. The specific mechanisms of action depend on the type of drug used.

Risks of drug abuse include mixing drugs, low tolerance, dropping out of treatment, not knowing enough about the drug, having mental health problems, and method of use.

Pills, help written on a paper, bottle, and a hand with pills.

What is drug overdose?

Drug overdose is the intake of a drug in amounts much higher than recommended, within a short timeframe. What can you overdose on? A person can overdose on a wide range of drugs from prescription opioids to illicit drugs, alcohol, and most other potent or addictive substances. When discussing “what is overdose,” it’s important to mention people can also overdose on herbal medicines, not just prescription medications.

Drug overdose can be accidental or intentional. Accidental drug overdose happens when a person takes the wrong substance or a combination of substances at the wrong time or in the wrong amount, without being aware of it. This also applies to people who take drugs to achieve a “high” effect but don’t know how potent they are. 

An intentional overdose happens when a person takes too much of a drug (or more of them) too quickly and on purpose. They want to inflict self-harm and choose drugs as a method to make it happen.

Overdose can be fatal and non-fatal. Not all cases of drug overdose lead to death, but they can have dangerous effects and consequences.

How common is drug overdose?

Drug overdose is common, but available numbers mainly focus on death cases. According to the National Institute on Drug Abuse, nearly 92,000 people in the United States died from a drug-related overdose in 2020. These also included people who took prescription opioids and illicit drugs. 

Men are more likely to overdose than women. The same report showed the prevalence of drug-related overdose among men was 69%. That means that 31% of drug overdose deaths account for women.

While fatal drug overdose cases are common, one report showed that for every 1 overdose death, there are 10 non-fatal overdose cases.

Drug overdose happens in people of all ages. A study from Pediatric Research found between 1999 and 2018, more than 1000 children under the age of 12 died from drug overdoses. In the period between 1999 and 2007, opioid overdoses accounted for almost half of pediatric patient deaths.

When it comes to adolescents, drug overdose cases are on the rise. One study found there were 518 drug overdose deaths among adolescents in 2010, but that number jumped to 954 in 2020.

In the elderly population, 55 years and older, drug overdose cases aren’t uncommon. In 1999, there were 518 drug overdose deaths in this age group, whereas that number in 2019 increased to 10,292.

What causes drug overdose?


Drug overdose is caused by a rapid and excessively high intake of a drug (or more of them) whose effects overwhelm the brain and body. The mechanism of action that leads to the development of overdose varies from one type of drug to another. 

For example, alcohol is absorbed through the proximal gastrointestinal (GI) tract and primarily metabolized in the liver. The main site of action of acute alcohol poisoning, or alcohol overdose, is the central nervous system (CNS). In the central nervous system, alcohol elevates CNS inhibition and reduces excitation. 

The primary inhibitory neurotransmitter in CNS is gamma-aminobutyric acid (GABA), which binds to receptors enabling chloride to enter the cell. As a result, cellular excitability weakens. As alcohol binds to GABA strongly, it activates an inhibitory cascade, which leads to problems such as impaired coordination, sedation, and cognitive dysfunction. In other words, drinking too much too quickly can overstimulate GABA pathways and induce symptoms of alcohol poisoning or overdose.

When it comes to cocaine, a paper from The Open Pharmacology Journal reports that at high concentrations, this drug can alter pathways in the brain. At the same time, cocaine can bind to sodium and potassium channels. As a result, cardiac effects of overdose occur. Both brain and body become overstimulated.

An opioid overdose happens due to the excessive effect of these drugs on the brain area that regulates the respiratory rate. This results in respiratory depression and may lead to death.

What are the symptoms of a drug overdose?

Symptoms of drug overdose sign and list.

Symptoms of drug overdose are greatly determined by the substances abused. The OD symptoms are particularly severe in persons who abuse two or more substances. The most common signs and symptoms of overdose are listed below.

  • Dilated or constricted pupils
  • Chest pain
  • Slurred speech
  • Problems with balance e.g., unsteady walking
  • Blue lips and/or fingers
  • Difficulty breathing e.g., shallow breathing or respiratory arrest (complete cessation of breath)
  • Slow or rapid heart rate
  • Very low or dangerously increased body temperature
  • Nausea and/or vomiting
  • Gurgling sounds (a sign of blocked airways)
  • Unconsciousness 
  • Unresponsiveness to shaking, loud noises, and painful stimuli
  • Seizures, convulsions, and/or tremors
  • Paranoia
  • Agitation
  • Hallucinations 
  • Aggressive behaviors
  • Confusion or disorientation
  • Coma 
  • Death 

What effects does drug overdose have?

Drug overdose has physical and mental or psychological effects. The severity of the effects depends on the type of substance or substances abused as well as how the body responds to them. The most common effects of drug overdose are listed below.

  • Physical effects: besides short-term effects such as breathing and heart rate changes, vomiting, nausea, seizures, changes in body temperatures, and cardiac arrest, drug overdose can have long-term effects that affect a person’s life after survival too. The most common long-term physical effects of drug overdose include toxic brain injury, liver damage, kidney damage, nerve damage, impaired cardiovascular health, long-term pain, reduced mobility, and dead limb or paralysis. Sometimes overdose can lead to compartment syndrome, which occurs when the pressure within the muscles reaches dangerous levels. It can lead to the loss of parts of the body or disfigurement. Other physical effects of drug overdose include vision loss and hearing problems.
  • Mental effects: short-term psychological effects of drug overdose include confusion, disorientation, paranoia, and problems with memory. Long-term mental effects of a drug overdose can lead to or aggravate major depression, anxiety, and other mental health disorders. People may also develop a fear of it happening again or become angry and feel betrayed by a person who supported their drug use. Additionally, a person develops persistent anger at themselves for failing to prevent overdose. Sometimes people take too much too quickly with someone else. Both persons may overdose and many cases are fatal. The person who survives and recovers often develops survivor guilt. Symptoms of survivor guilt include flashbacks of the traumatic event, irritability, feelings of helplessness and disconnection, and problems sleeping.

How to prevent drug overdose?

Woman taking a pill.

To most reliable way to prevent drug overdose is preventing substance use disorder in the first place, according to the U.S. Department of Health and Human Services. Prevention strategies also focus on harm reduction, evidence-based treatments, and recovery support. 5 tips to prevent a drug overdose are listed below.

  • Avoid mixing: many overdoses result from combining alcohol and medications such as benzodiazepines. Both are central nervous system depressants. and combining them can lead to overdose and respiratory failure. Generally speaking, it is necessary to avoid mixing alcohol with medications prescribed by a doctor.
  • Watch out for fentanyl: it’s a synthetic opioid known for being 50 times more powerful than heroin. Many cases of drug overdose occur due to the unknown presence of fentanyl. Not only is it added to heroin, but also some prescription pills obtained from illicit sources.
  • Seek help early: reach out to a family member, friend, therapist, or other healthcare professional as soon as signs of substance use disorder or problematic use of drugs and alcohol appear. People concerned with the well-being of their friends or family members may want to stage an intervention. Seeking help early is crucial for preventing overdose.
  • Minimize the risk of relapse: upon completing drug addiction treatment, make sure to go to support groups regularly and avoid socializing with people who abuse drugs or alcohol. This will reduce the risk of relapse, which could lead to overdose otherwise.
  • Get naloxone: individuals at risk of opioid overdose or relapse may want to find out which agencies have free naloxone kits available. This medication can block the effects of opioids and restore respiratory function. That way, naloxone can prevent complications associated with overdose.

What are the risks of a drug overdose?

Risks of a drug overdose sign and a list

The biggest risks of drug overdose are listed below.

  • Low tolerance: people with low tolerance to a specific drug or those experiencing a reduction in tolerance are more susceptible to overdose. This is particularly the case when the drug is potent or taken in higher amounts. A person with low tolerance to some drugs can develop an overdose faster.
  • Mental health problems: some mental health conditions, such as depression, increase a person’s risk of both fatal and non-fatal overdoses. Psychotic disorders and PTSD can also make a person more likely to overdose. Mental health problems can also increase the risk of substance use disorders and interfere with a person’s ability to make health care decisions. They may also lead to engaging in unhealthy behaviors that serve as coping mechanisms. For that reason, a person may keep gradually increasing the doses they’re taking, thus putting themselves at risk of a drug overdose.
  • Method of use: people who opt for intravenous routes are more susceptible to drug overdose than persons who choose other methods. Of course, this doesn’t mean other methods of use are safe. Some drugs carry a high risk of overdose even if you don’t administer them intravenously. 
  • Mixing drugs: taking multiple substances, including prescription pills, at the same time puts a person at a high risk of overdose. The same applies to combining drugs with alcohol. Sometimes people experiment with different substances and combinations of drugs. While it may seem exciting and gives them the “high” effect, it can be incredibly dangerous. 
  • Not knowing enough about the substance: prescription drugs are easier to dose because their production is regulated, and doctors prescribe a specific dosage based on the patient’s needs. Yet, overdose can still happen. Illicit drugs and other illegal substances are different because it’s impossible to know enough about these drugs. A specific drug may be cut and combined with other drugs without a person being aware of it. Also, buying prescription pills illegally can be dangerous because they may contain other substances too. Lack of accurate knowledge about the substance puts a person at risk of overdose.
  • Using alone: the risk of overdose is higher when a person is using alone, and there’s nobody to notice symptoms that say something is wrong.
  • Failing to stick to the treatment: dropping out of addiction treatment can put a person at risk of overdose. Some people drop out due to withdrawal symptoms, whereas others may feel better and assume there’s no need to stick to the end of the treatment. Regardless of the cause for dropping out of treatment, doing so can pave the way to risk behaviors that result in overdose.

What are the possible treatments for a drug overdose?

Treatments for drug overdose sign and a list

Possible treatments for drug overdose depend on the drug taken, the dosage, when and how the drug was taken, whether it was consumed with other substances, and the effect on the person. The success of the treatment depends on a timely response. As soon as symptoms of overdose appear, it is necessary to get urgent medical assistance, administer naloxone (if there are some), and stay with an affected individual until help arrives.

Hospital treatments for drug overdose are listed below.

  • Full assessment in the emergency department (ED): this includes blood tests, psychological evaluation, and observation.
  • Removal of substance out of the body: usually with activated charcoal, which works by binding the drug to prevent the body from absorbing it.
  • Administration of antidote (when possible): doctors may administer drugs such as naloxone to reverse the effects of an overdose.
  • Admitting a patient into a hospital: once a patient’s life isn’t in danger and treatment in the ED is completed, a patient may be admitted into the hospital for further treatment. The treatment depends on the effect of overdose or complications on the body.
  • Addiction treatment: many patients are enrolled in addiction treatment following an overdose. The treatment for substance use disorders is tailed to the special needs of each patient. In most cases, the treatment includes detox, inpatient or residential treatment, luxury rehabs, outpatient programs, and support groups.

Is it possible to overcome drug overdose?

Yes, it is possible to overcome drug overdose. Surviving drug overdose depends on timely treatment. The most important factor in overcoming drug overdose and achieving recovery is getting the necessary treatment without delays. Recovery duration depends on the effects of the overdose on the body i.e., the extent of organ damage and other complications. Non-fatal drug overdoses are more frequent than fatal overdose cases, WebMD confirms.

Self-care after treatment plays an important role in overcoming drug overdose. That means a patient should adhere to all doctor’s instructions and make necessary lifestyle adjustments. A healthy lifestyle is incredibly important to both physical and mental health.

Major support for overcoming drug overdose and addiction comes from therapy sessions. Therapy is integrated into inpatient and outpatient treatment programs. The exact type of therapy may vary, but in most cases, patients receive cognitive-behavioral therapy (CBT), individual counseling, group counseling, and also medication-assisted treatment (MAT).

The role of therapy is to help a patient focus on identifying irrational or dysfunctional thoughts that lead to negative emotions and dangerous behaviors. Once these thoughts are identified, patients learn skills to change them into functional, more positive alternatives that lead to positive emotions and healthy behaviors. 

Overcoming drug abuse can be challenging and lengthy, but with a strong support system and proper treatment, a patient can improve their quality of life.