Most Dangerous Drugs

While any drug can be abused, even those drugs without the risk of physical dependence, the most commonly abused and dangerous drugs all have one thing in common: these drugs hijack the brain’s normal function and alter it, either chemically, physically or both. In particular, opioids derange the brain’s neurotransmitter system, especially the chemical messenger dopamine and cause the brain to actually grow extra opioid receptors.

Most Dangerous Drugs

Extra opioid receptors are dangerous because they may directly lead to opioid overdose when a highly tolerant opioid abuser chases that so-elusive initial rush and takes a lethal dose.

The Brain’s Neurotransmitter System

To better understand how addictive drugs lead to addiction, you must first understand the role of neurotransmitters in the brain. These are critical chemicals that allow brain cells to communicate. One brain cell or neuron will release a neurotransmitter into the space between it, called the synapse, and its neighbor neuron. This neuron then does the same and so on. It’s all mediated through a system called reuptake.

Different neurons have different functions. For example, the neurotransmitter serotonin is known to regulate mood. It may surprise you to learn that most of the brain’s serotonin is manufactured in the gut from an amino acid called tryptophan.

Red meats, turkey and nuts are good sources of this protein building block. Called the happy chemical, serotonin levels are directly related to the risk of depression. Prescription drugs like Prozac target this serotonin system to relieve depression.

The Brain’s Dopamine System

You may wonder what all that has to do with drug addiction. It has to do with yet another neurotransmitter called dopamine. Dopamine is known to be connected to feelings of happiness, pleasure and reward. It flows through the neurons and is responsible for the pleasure experienced by food, sex, hobbies, falling in love and important relationships. All of these things can cause the release of small amounts of dopamine. This is part of normal brain function.

Dopamine and Drugs of Abuse

All drugs of abuse have one thing in common, at least to some degree: they greatly influence the brain’s dopamine system, causing the neurotransmitter to flood the brain’s neurons, resulting in an artificially high brain dopamine environment. This is not normal and is damaging to normal dopamine function. For one thing, when a drug of abuse is suddenly stopped, the addicted brain, now used to very abnormally high dopamine levels, can no longer function without the drug. This is one likely cause of both drug cravings and withdrawal symptoms. Withdrawal symptoms will persist until the brain ramps up normal neurotransmitter production again.

Physical withdrawal symptoms will diminish over time, but drug cravings may be present for months, years and even permanently. Many people with these cravings will independently report that there is a constant feeling of “something missing” or that “the colors of life are gone.” There is no question that the complete mechanisms of the addicted brain are not that well understood at this time. But, we do know that dopamine plays a critical, although not singular, role in drug addiction.

Addiction and Genetics

Genetics influences up to half of an individual’s risk of drug addiction. This is the luck of the draw. Genetics alone are not the sole cause of addiction because other strong factors exist. However, a family history of substance abuse should serve as a word to the wise.

The Most Dangerous Drugs


Surprised? Nicotine is a poison actually used as a pesticide. It’s a stimulant causing the brain’s neurotransmitters to flow faster. It’s a myth that smoking tobacco is relaxing. Smokers may perceive nicotine’s effect as “relaxing” when all it’s really doing is supplying the addicted brain with more of the nicotine it craves.

Stimulants increase anxiety and promote insomnia. Nicotine is a highly addictive and toxic drug harmful to health. It raises blood pressure and heart rate. It contributes to narrowing the heart’s arteries, reducing blood flow and making the heart work harder. This directly raises the risk of a heart attack. Worse, nicotine is airborne and present in high concentrations in second-hand smoke. Nonsmokers inhale this toxic chemical. As you may have already figured, vaping nicotine products does nothing to reduce your risk of nicotine’s harmful effects.

Nicotine produces a powerful addiction that is very hard but not impossible to break. Nicotine replacements and effective prescription medications are available.

Heroin and Other Opioids

Although heroin carries a special stigma in our society, it wasn’t always that way. In fact, until 1914, heroin was a common ingredient in patent medicines available over the counter and through the mail. These opioid medicines were in many households and used all the time for pain, cough, stomach problems and diarrhea. Heroin has always been one of the most dangerous drugs, then and now.

Tragically, opioid patent medicines were also used for teething and colicky babies to soothe them. Patents didn’t realize the danger. The products were effective, but dosing an infant with heroin is tricky. Infant death from patent opioid medicines occurred regularly, although it wasn’t recognized as such at the time because infant deaths from many causes was so commonplace. Babies died; it was a sad fact of life.

Heroin is not legal in the United States and hasn’t been since 1924. However, it behaves in the body the same as prescription opioids like oxycodone, fentanyl, methadone and hydrocodone. They all target the brain’s opioid receptors, especially one called the mu receptor. They can all cause profound and undesirable brain structure and function changes with regular use. The brain addicted to opioids has abnormal dopamine function and extra opioid receptors. These extra receptors are not supposed to be there. This brain will also stop producing its own natural opioids called endorphins. The opioid-addicted brain is a disaster, but with time and proper therapy, it can heal.


Depending on your source, alcohol is either the most common or second most common (after or before nicotine) drug of abuse in the United States. Definitely one of the most dangerous drugs, alcohol is a brain and body poison. The liver must detoxify it and with regular exposure, may develop cirrhosis, which causes fatty deposits in place of healthy liver tissue.

Alcohol damages the brain and heart and causes FAS or fetal alcohol syndrome. There is no such thing as safe alcohol consumption during pregnancy. No one knows what level of alcohol exposure may cause FAS.


What is the worst drug? Although not widely known or abused in the United States, krokodil is commonly abused in Europe, especially in Russia. Low-dose codeine combination products may be purchased without a prescription in these countries. Abusers mix these codeine pills with very poisonous chemicals like paint thinner and gasoline to make a highly noxious and toxic opioid brew called krokodil. Injected into a vein, these toxins cause skin lesions resembling crocodile skin, hence the moniker krokodil. It can also cause gangrene and loss of healthy skin tissue with exposure of bone. Krokodil is ghastly; regular users typically die within two years.

In pure form, the opioid in krokodil is known chemically as desomorphine.


What? Tylenol? A dangerous drug??? You bet! Although not a drug of abuse in itself, acetaminophen is a common ingredient in combination prescription opioids like Vicodin, Percocet and generic equivalents too numerous to name. Acetaminophen is a direct liver toxin. People taking too many hydrocodone or oxycodone with acetaminophen pills to get more opioid also ingest more acetaminophen.Doses exceeding 4 grams a day may cause permanent liver damage, especially over time. Single doses higher than 8 to 10 grams or lower doses repeated over and over can cause sudden liver failure if the overdose is not treated immediately. This treatment window is very small. If damage is too severe, you will be facing either a liver transplant or death.

Never exceed recommended doses for this drug. It can kill.

What are the 6 Dangerous Drugs?

In this context, dangerous is a relative word because all drugs can be dangerous, as we have seen with Tylenol. However, six drugs that would definitely qualify are:

  • Alcohol
  • Nicotine
  • Heroin
  • Krokodil
  • Flunitrazepam (Rohypnol)
  • Fentanyl

Fentanyl is very dangerous because it’s so powerful. The dose is in micrograms or millionths of a gram. This means that an amount represented by 2 to 3 grains of salt is enough to kill. Fentanyl is also becoming a common ingredient in street heroin and counterfeit opioid pills pressed to look like the real thing. Users unaware of the drug’s presence take these products and die before help can even arrive.

If you know or even suspect someone close to you is abusing opioids, consider purchasing the opioid overdose rescue drug naloxone. Ask your local pharmacy. You don’t need a prescription, and it’s easy to administer. Naloxone can keep an opioid overdose victim breathing long enough for help to arrive.

Flunitrazepam, another contender for one of the most dangerous drugs,is also called the date rape drug. Odorless and near tasteless, the drug is slipped into a drink and used by rapists to incapacitate their victim. The drug also wipes out short-term memory, leaving the victim unable to assist law enforcement.

What are the 3 Most Commonly Abused Drugs?

This would most likely be marijuana, including delta 8 products, nicotine/tobacco and alcohol. Neither tobacco nor alcohol require a prescription and anyone of age can legally buy them. As more states legalize recreational marijuana, it also is becoming easy to get. It’s interesting that states with legal marijuana have lower opioid abuse rates!

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We’re here to help with any kind of drug abuse issue. We offer hope, treatment referrals, detox options and information. Don’t let fear of withdrawal stop you from seeking treatment. Our detox centers offer the best in safe and comfortable withdrawal protocols. The sooner you call us, the sooner we can help.