What Is The Worst Drug?

It’s only natural to want to know what’s best or worst, good or bad. That’s why we love these types of lists! But in the case of drugs and alcohol, there isn’t a “worst” just as there isn’t a “best” drug.

We don’t define drugs as most or least harmful. All drugs have the potential to produce negative health effects or lead to a dangerous situation in the short or long term. Whether a drug causes a serious health issue—like a life-threatening overdose—can depend on how much a person uses, how they consume it, and other factors.

However, some drugs are so potent that a life-threatening overdose can occur the first time a person uses them. For example, the synthetic opioid fentanyl is 100 times more potent than morphine and 50 times more potent than heroin. Because fentanyl is often mixed with other drugs, such as heroin, cocaine, methamphetamine, and MDMA (Molly), fentanyl may be ingested unknowingly at unknown quantities, which can lead to overdose. Injecting potent drugs can be particularly dangerous because this route delivers the compounds more directly to the brain than ingesting or snorting drugs. Injection also carries the risks of injury and infection.

Similarly, some drugs are more frequently associated with addiction and dependence than others. For example, more than half of people who regularly use cigarettes meet the criteria for a tobacco use disorder, while only about 1 in 11 people who regularly use marijuana (cannabis) meet the criteria for a cannabis use disorder. Certain drugs can have a stronger effect on the brain than others. Research has shown that methamphetamine, in particular, may damage cells and structures within the brain that can cause long-term problems with emotion and memory.

Certain physical or mental illnesses, as well as family health history, also influence someone's chances of developing an addiction or other negative health effects of drug use. Age is an especially important factor when calculating the risks of substance use. Because the brain develops through a person’s mid-twenties, teens and young adults tend to be more vulnerable to negative health effects of many drugs. All of this means certain substances may pose different risks to different people in different situations.

Going by the numbers, determining the deadliest drug also depends on perspective.

In 2019, an estimated 70,630 people died from a drug-involved overdose in the United States. The most common drugs associated with these fatal overdoses were synthetic opioids, including the highly potent synthetic opioid fentanyl.

However, the long-term health effects of cigarette smoking are responsible for more than 480,000 deaths per year. That’s about 1,300 deaths every day.

And alcohol is the substance most frequently involved in deadly car crashes. Nearly one person died every 52 minutes from drunk driving crashes in 2019, and that's in the United States. It's possible it's even worse, relative to the given population, in South Africa.

To put it simply, what's the "worst" drug isn't an easy question to answer, and it’s important to understand the risks of any substance. There is ongoing research to help us understand the effect of drugs on the brain, how to prevent people from starting to use drugs, and how to help them if they have substance use disorder.

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