How Much Heroin Does It Take To Overdose?

People who use heroin have to take more and more of the drug over time, which leads to increased risk of fatal overdose. Yet even first-time users can overdose because of additives to the drug. The amount of heroin it takes to overdose may depend on several factors.

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Dr. Langdon M.D.

Medically Reviewed By: Kimberly Langdon M.D.


It is important to understand that even a first-time user can experience an overdose from heroin.

Because the drug is made and sold illegally, it often has additives such as fentanyl that increase the power of the drug. This means that even if you take a dose that you have taken before, you are still at risk of overdose.

Also, the amount of heroin it takes to overdose, whether fatal or non-fatal, varies widely due to a number of factors.

Find out more about heroin overdose.

How Much Heroin Does It Take For A Non-Fatal Drug Overdose?

Overdose deaths can result from any amount of the drug depending on who is taking it, how long that person has been taking it, and what has been added to the drug.

This is because many factors can affect whether heroin drug use can cause an overdose, including a person’s physiological makeup, tolerance level, and more.

The Lethal Dose Of Heroin

According to the Centers for Disease Control and Prevention (CDC), drug overdose deaths from heroin are on the rise.

A fatal overdose of heroin is most likely to take place under a couple of different circumstances.

Heroin addiction may result in fatalities from people taking more of the drug than previously to get the same high.

Another circumstance that can create a lethal dose of heroin is if the drug is mixed with fentanyl.

Because fentanyl is a powerful narcotic, the side effects from the combination of these two drugs can result in lethal respiratory depression.

Learn about heroin overdose death rates.

Factors That Affect Heroin Toxicity

There are many factors that can affect the toxicity of heroin and result in an opioid overdose.

Some of these factors have to do with the individual and their tolerance to the drug, but others have to do with the drug itself.

Individual Factors

Just as with prescription drugs, the effects of opioid use can change according to the size and weight of the individual.

A person who is smaller and weighs 120 pounds is going to experience heroin more intensely than a person who is tall and weighs 250 pounds.

Heroin Tolerance Level

People who have become addicted after a long time of heroin use stand a greater chance of heroin overdose deaths.

Pretty quickly after the first dose, heroin users require more of the drug in order to achieve the intensity of the original high. With increased substance abuse, they build a tolerance to heroin.

This can be dangerous for them because they stand a greater chance of taking a non-fatal or fatal dose of the drug in order to get the high that they want.

Use Of Heroin Cutting Agents

Street heroin is not always pure heroin. It is often “cut” with other substances, prescription opioids, or synthetic opioid agents and sold as pure heroin in order to stretch out the product and make more money.

Substances used to cut heroin sometimes include:

  • powdered milk
  • starch
  • sugar
  • quinine

People who are used to taking the drug cut with sugar can unpredictably get a dose cut with quinine (which can slow respiratory function), prescription opioids, or a pure dose of heroin.

They can overdose from substance use thinking they are taking the amount that they normally take.

Presence Of Other Illicit Drugs

Heroin can also be mixed or “cut” with other drugs that can increase the chance of overdose. For example, heroin is often cut with fentanyl, a prescription painkiller, which can create a lethal dose of the drug.

Is There A Safe Dose Of Heroin?

The simple answer is no. Heroin is an illegal drug and a poison to your body. Just because you survive one or more doses does not mean it is safe.

Because you can never guarantee what is in heroin, you cannot guarantee you will not experience overdose with each new dose you take.

The ultimate harm reduction is to not take the drug at all.

Heroin Overdose Treatment

Heroin overdose treatment often involves a drug called naloxone (Narcan), which is given by first responders.

Naloxone attaches and binds to the opioid receptors in the brain, just like heroin or other opiates.

But naloxone attaches to those receptors, blocking heroin from attaching. If given promptly, naloxone can begin reversing the effects of a heroin overdose on the way to the emergency room.

Find Treatment For Heroin Overdose And Addiction

If you or one of your family members are addicted to heroin, you stand a high chance of overdosing from the drug.

But help for heroin addiction is available through treatment providers who use medically assisted treatments to address heroin withdrawal symptoms with medications such as methadone.

Call our helpline to find a drug addiction treatment center and related healthcare options near you or your loved one.

  1. Centers for Disease Control and Prevention
  3. National Institute on Drug Abuse
  4. U.S. National Library of Medicine: MedlinePlus
  5. U.S. National Library of Medicine: MedlinePlus

Written by Bedrock Recovery Center Editorial Team

© 2024 Bedrock Recovery Center | All Rights Reserved

* This page does not provide medical advice.

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