If a drug is extremely addictive, it’s dangerous and deadly. Abuse causes tolerance, which leads to overuse. In many cases, addiction leads to heart and liver disease. The deadliest drugs in the world include opioid drugs, stimulants and prescription medications.

What are the most deadly drugs?

The World’s Most Dangerous Drugs in the US

Drug abuse is unhealthy, dangerous and often deadly. Drugs are even more dangerous and lethal when mixed with other substances. A lot of fatal overdoses involve a primary hard drug (heroin, fentanyl), other drugs (speed, cocaine) and alcohol abuse.

In some cases, dangerous drug addiction stems from the overuse of a prescription drug. Though people take these medications to treat severe pain, some (methadone, morphine) can be the cause of drug overdose deaths.

According to the December 2018 National Vital Statistics Report, the most deadly drugs are the following:

1. Fentanyl: Most Dangerous Drug

Fentanyl is a synthetic opioid used in pain-relief medications. It has since proliferated as a recreational depressant. Fentanyl is 50 times more powerful than heroin and currently the nation’s deadliest drug.

• Fentanyl symptoms – Fentanyl produces feelings of euphoria, relaxation, dizziness and sedation.
• Fentanyl withdrawal – Hardcore signs of fentanyl abuse and withdrawal include nausea, vomiting, urinary problems, constricted pupils and respiratory problems.

During the 2010s, fentanyl went from being the ninth deadliest drug (2011) to the deadliest drug, accounting for 18,335 deaths (28.8%) in 2016.

2. Heroin

Heroin is a depressant opioid derived from morphine. It skyrocketed as a recreational drug in the 1970s rock scene. Famous casualties include singers Jim Morrison and Janis Joplin and comedian John Belushi.

• Heroin symptoms – Heroin creates euphoric sensations that are mentally and physically addictive on first use. Bodily tolerance leads to heroin abuse, usually within the first week.
• Heroin withdrawal – During heroin detox, users often experience depression, irritability, extreme cravings, shakes, sweats, chills and muscle cramps.

For years, heroin was the nation’s deadliest drug. As of 2016 (15,961 deaths), it has been eclipsed by fentanyl, which is often added to cheap street heroin supplies. 

3. Cocaine

Cocaine is a stimulant drug that people take at parties for energy and euphoria. It became a popular drug on the ’70s disco scene. Cocaine is typically dispersed in powder form and snorted.

• Cocaine effects – Users are typically restless, euphoric and disengaged from reality. The drug can cause mania (excessive happiness, even in bad situations) and sexual arousal.
• Cocaine withdrawal – Extreme cravings, depression, loss of libido, fatigue and inability to feel pleasure.

Cocaine is addictive because it triggers the brain’s reward centers. Tolerance leads to overuse of the stimulant, which can lead to arrhythmia and hypertension. Cocaine is especially dangerous when mixed with downers. Cocaine caused 19,447 deaths in 2020.

4. Methamphetamine

Methamphetamine is a stimulant that works on the central nervous system. As a recreational drug, it’s known as speed, meth and crystal. Speed became a popular drug on the ’70s punk scene.

• Meth effects – Speed causes bursts of energy, mania and sexual desire. Rock musicians used speed to stay awake for days and nights through grueling tour schedules and recording sessions.
• Adverse effects – Signs of meth addiction include grinding teeth, acne, paleness, dilation, sores and flushed skin.

Meth is typically taken as an intravenous drug. During the ’80s and ’90s, this was a major cause of HIV infection. Overdose deaths tripled between 2015 and 2019. In 2016, 6,762 people died from the drug.

5. Alprazolam

Alprazolam, commonly known by the brand name Xanax, is a prescription medication used to treat depression, anxiety and panic disorder. Like other benzodiazepines, people often abuse Xanax as a recreational drug.

• Xanax abuse – The short-term effects of Xanax abuse include muscle weakness, drowsiness, lack of inhibition, poor concentration and amnesia.
• Xanax withdrawal – After long periods of abuse, Xanax abstinence often causes hallucinations, panic attacks, sweats and seizures.

People who suffer panic disorders often grow addicted to Xanax by exceeding the prescribed dose. Alprazolam caused 6,209 deaths in 2016.

6. Oxycodone

Oxycodone is a pain-relief medication prescribed under the brand names Roxicodone and OxyContin. It’s a Schedule II drug that can only be obtained legally by a doctor’s prescription.

• Oxycodone effects – The side effects of use and overuse include constipation, dizziness, euphoria, lack of appetite, dry mouth, itching and sweating.
• Oxycodone withdrawal – People who abruptly stop the drug may experience anxiety, nausea, vomiting, restlessness, diarrhea and faster heart rates.

As with other pain relievers, people often overuse oxycodone. This causes tolerance and diminishes the benefits. In 2016, 6,199 people died from oxycodone abuse.

7. Morphine

Morphine is a medication derived from the opium poppy, prescribed for acute and chronic pain. Doctors administer the drugs into the muscle tissue and around the spinal cord. It’s also used to treat pain for kidney stones and labor.

• Morphine effects – Depression, loss of appetite, dizziness, dry mouth and itchiness.
• Morphine addiction signs – Loss of sexual function, immunodeficiency, vomiting, hallucinations, respiratory depression, loss of testosterone.

People grow addicted to pain relievers like morphine because they overestimate how much they’ll need for relief. In 2016, 5,014 people overdosed on morphine.

8. Methadone

Methadone is another opioid used for pain relief. Methadone is taken orally to curb withdrawal symptoms from hard drugs like heroin. When abused, methadone has adverse effects.

• Methadone effects – Sedation, dry mouth, weakness, heat sensitivity, headaches, insomnia and memory loss.
• Methadone withdrawal – Fever, nausea, light sensitivity, aching limbs, dilated pupils, fast heartbeat, tremors, urinary difficulty.

Methadone is a Schedule II drug with a high-abuse potential. For heroin withdrawal, it’s only meant to be taken for a short period. Unfortunately, it’s often used as a replacement drug. In 2016, 3,493 people died from methadone overdoses.

Find Treatment for Substance Abuse

Though most people associate substance abuse with fatal overdose cases, prescription opioids can also be highly addictive. According to the Centers for Disease Control, 500,000 people died from opioid prescription drugs and illicit drugs between 1999 and 2019. 

If someone you know has a deadly drug addiction, get help immediately. Don’t let your friend or loved one become another statistic. Call the treatment centers in your area and ask about their rehab programs. Your call could save a life.