5 Deadliest Drugs

In 2006, Professor R. S. Gable published a graph comparing the toxicity levels and dependence potential of certain commonly abused drugs. In other words, how addictive is a drug vs. how toxic is it?

Of course, the most dangerous drug would be the most toxic and the most addictive.

From this graph, we’ve compiled a list of the five most dangerous drugs.

Note: This information is pulled from a scientific study and ranks drugs compared to one another. For that reason, do not take an addictive potential ofModerate/Low” as a statement that a drug is not dangerous. It is only less potentially addictive than other highly dangerous drugs.

5. Marijuana


Marijuana is one of the most broadly abused street drugs in America. Known as the “gateway drug,” its potency has increased markedly in the past four decades as farmers cultivate stronger and stronger strains of the cannabis plant. Marijuana is often a teenager’s first drug experience—but rarely his or her last.

Addictive Potential: Moderate/low

Toxicity Level: It takes about 1000 active doses(*) of marijuana for the drug to become lethal.

4. Ecstasy


Ecstasy, or MDMA, has become popularized as a party drug. A Schedule I controlled substance, it is frequently abused at night clubs and “raves.” Ecstasy users experience euphoria, altered consciousness and euphoria while high on the drug, followed by a psychological and physical “down” after the drug wears off. Many Ecstasy-related deaths have resulted from party-goers dehydrating while using the drug.

Addictive Potential: Moderate/Low

Toxicity Level: It takes about 15 active doses of Ecstasy for the drug to become lethal.

3. Alcohol


While alcohol is actually a legal drug, it makes the list at number 3. Statistically speaking, alcohol sends more Americans to drug rehabs than all other drugs combined. It is also behind more fatalities than any other drug. This is due to the widespread abuse of alcohol in the U.S. Scientifically speaking, alcohol is moderately addictive and highly toxic to the body.

Addictive Potential: Moderate

Toxicity Level: It takes about 10 active doses of alcohol for the drug to become lethal.

2. Cocaine


While the dangers of cocaine are well-known and have even been featured in movies (Scarface et al), it doesn’t take the #1 spot. Cocaine addicts have reported getting hooked on the drug after only one hit. Cocaine and crack cocaine are one of the major causes of crime in the U.S. Nearly 20% of all inmates are imprisoned for crimes they committed in an effort to obtain drug money, and much of this is cocaine or crack-related.

Addictive Potential: Moderate/High

Toxicity Level: It takes about 13 active doses of cocaine for the drug to become lethal.

1. Heroin


Heroin is by far the most addictive and lethal of the drugs subjected to this study. Not only do heroin users suffer a high fatality rate compared to the rest of the population. Heroin is extremely difficult to quit. The drug ravages its user’s health and makes him or her totally dependent.

Addictive Potential: High

Toxicity Level: It only takes about 5 active doses of heroin for an overdose to occur. Because of the variations in heroin purity, this low “margin in error” results in many addicts accidentally overdosing.


The best way to help your friends and loves ones avoid the dangers of drugs is to keep them informed. If you feel you learned something new from this article, please share it on Facebook to your friends. You’ll be helping us keep more people off drugs.

What drug do you feel is the most dangerous?

*An “active dose” is commonly referred to as a hit or shot. Scientifically it’s the minimum dose required in order to have a noticeable effect on the mind or body.



Aaron has been writing drug education articles and documenting the success of the Narconon program for over two years.