**Question:** Why is it that psychoactive or "feel good" drugs tend to be dangerous? **Answer, in short:** They are not necessary dangerous *as such,* that is because of their inherent properties, but mainly because people *tend* to **overuse** and **overdose** them. **The focus in the question and in this answer is on "feel good" and not on "illicit" drugs,** especially on opioids, benzodiazepines, amphetamines, cocaine, MDMA and alcohol. A [psychoactive drug][1] is a chemical substance that changes brain function and results in alterations in perception, mood, consciousness, cognition, or behavior. Most dangers of psychoactive drugs stem from oversuse: **1) Overdose** Opioids, such as heroin, in high doses can cause [respiratory depression][2]. There are antidots and other treatments available, but with illicit opioid use, there are usually no doctors around, so this is why overdose can be deadly. According to [Drugabuse.gov][3]: "Every day, more than 130 people in the United States die after overdosing on opioids" and "Roughly 21 to 29 percent of patients prescribed opioids for chronic pain misuse them." **2) Addiction** Addiction is often associated with a dose and duration of use. Moderate alcohol drinking (1-2 drinks/day) does not likely make you addicted, but higher amounts drunk for several months/years can. [Alcohol dependance and withdrawal][4]. **3) Withdrawal** [Abrupt withdrawal from alcohol][5] after long alcohol use can be deadly due to seizures or arhythmia, for example. [Opiate withdrawal][6] can also be deadly. Benzodiazepines withdrawal can result in [rebound insomnia and rebound anxiety][7]. **4) Organ damage** Physical complications after prolonged use (years): - Alcohol: [liver cirrhosis][8], [alcoholic neuropathy][9], [Wernicke-Korsakoff syndrome][10] - Cocaine: [brain damage][11] (acute effect can be [gastric ischemia][12]) - Methamphetamine: [brain damage, tooth decay (meth mouth)][13] In conclusion, many "feel good" psychoactive drugs are dangerous mainly because they can be easily overdosed. Most of them have a "narrow [therapeutic index][14]:" alcohol, [benzodiazepines][15], cocaine, [opioids][16]. **"Emergency room visits due to "feel good" drugs** Emergency room visits ratios in the US, 2011 ([ussc.gov][17]): *V = ER visits/year ; RR = risk ratio (total users/ER visits)* ```` - V RR - PCP (phencyclidine) 75,538 2.9 - Heroin 258,224 0.92 - Oxycodone/oxycontin 151,218 0.39 - Cocaine 505,224 0.37 - Methamphetamine 102,961 0.23 - MDMA (Ecstasy) 22,498 0.04 - Marijuana 445,668 0.03 - LSD 4,819 0.03 ```` If you evaluate *danger* by ER visits, the relative risks do not appear high, but absolute numbers do for most listed drugs. **Road accidents associated with "feel good" drugs** > The risk for road trauma was increased for single use of > **benzodiazepines** (adjusted OR 5.1 (95% Cl: 1.8-14.0)) and **alcohol** (blood alcohol concentrations of 0.50-0.79 g/l, adjusted OR 5.5 (95% Cl: 1.3-23.2) and >or=0.8 g/l, adjusted OR 15.5 (95% Cl: > 7.1-33.9)). High relative risks were estimated for drivers using **combinations of drugs** (adjusted OR 6.1 (95% Cl: 2.6-14.1)) and those using **a combination of drugs and alcohol** (OR 112.2 (95% Cl: > 14.1-892)). Increased risks, although not statistically significantly, were assessed for drivers using amphetamines, cocaine, or opiates. No > increased risk for road trauma was found for drivers exposed to > cannabis. [1]: https://en.wikipedia.org/wiki/Psychoactive_drug [2]: https://www.ncbi.nlm.nih.gov/pubmed/30735692 [3]: https://www.drugabuse.gov/drugs-abuse/opioids/opioid-overdose-crisis [4]: https://www.drinkaware.co.uk/alcohol-facts/health-effects-of-alcohol/mental-health/alcohol-dependence/ [5]: https://www.drugfoundation.org.nz/matters-of-substance/november-2011/mythbusters-death-by-withdrawal/ [6]: https://ndarc.med.unsw.edu.au/blog/yes-people-can-die-opiate-withdrawal [7]: https://www.ncbi.nlm.nih.gov/pubmed/6132413 [8]: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5513682/ [9]: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3370340/ [10]: https://rarediseases.org/rare-diseases/wernicke-korsakoff-syndrome/ [11]: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3943678/ [12]: https://medcraveonline.com/IJRRT/IJRRT-05-00125.php [13]: https://www.drugabuse.gov/publications/research-reports/methamphetamine/what-are-long-term-effects-methamphetamine-misuse [14]: https://en.wikipedia.org/wiki/Therapeutic_index [15]: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5896864/ [16]: https://www.ncbi.nlm.nih.gov/pubmed/21999760 [17]: https://www.ussc.gov/sites/default/files/pdf/amendment-process/public-comment/20170807/FPD.pdf [18]: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4107777/