Drug Addiction: 5 Substances With Dangerous Side Effects

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Drug addiction can have detrimental side effects and disrupt normal body functions. Some substances are more dangerous than others based on their short-term and long-term impact on the brain and body. The following are five drug addictions that can have severe and even life-threatening effects.

1. Alcohol

While legal, alcohol is considered a type of drug, classified as a depressant. A depressant slows down a person’s vital functions (e.g., perception, speech, and movement).14

Alcohol can have adverse effects on nearly every part of the body, including the brain, heart, and bones.1 Alcohol’s impact is strongly affected by the amount and duration of its use.

Short-term effects of alcohol misuse may include:1

  • Losing balance and coordination
  • Impaired judgment
  • Dehydration
  • Nausea
  • Vomiting

Drinking large amounts of alcohol for an extended period can damage your organs, such as your brain, nervous system, heart, liver, and pancreas.1,2  Long-term alcohol misuse can also lead to health conditions linked with vitamin deficiencies and a wide range of health conditions, including:1

  • High blood pressure
  • High cholesterol
  • Stroke
  • Heart attack
  • Weakened immune system
  • Osteoporosis, or weakening of the bones
  • Pancreatitis, or inflammation of the pancreas
  • Liver disease (e.g., hepatic encephalopathy)
  • Certain types of cancer (e.g., breast, bowel, head, and neck cancer)

Long-Term Effects of Alcohol on the Heart

Long-term alcohol misuse can lead to high blood pressure and high cholesterol levels. Both conditions increase your risk of heart attack and stroke.1 Alcohol misuse can cause irregular heart rate (arrhythmias) or weakening and enlargement of the heart due to changes in blood volume and pressure (alcoholic cardiomyopathy), causing insufficiency of the heart’s ability to pump blood effectively.2

Long-Term Effects of Alcohol on the Liver

Your liver is the primary organ responsible for breaking down and eliminating alcohol from your body. Prolonged alcohol misuse can damage your liver, which may lead to a severe brain condition called hepatic encephalopathy. Symptoms of hepatic encephalopathy may include:3

  • Sleep disturbances
  • Problems with attention span
  • Anxiety
  • Depression

Over time, chronic alcohol misuse can damage the liver in various ways, including:2,4,5,6,7

  • Alcoholic hepatitis—An inflammation of the liver caused by toxic chemicals that your body produced by the breakdown of alcohol. These chemicals cause liver inflammation and destroy liver cells.
  • Cirrhosis of the liver—The end-stage of alcoholic liver disease, which occurs when liver inflammation causes scarred tissue in place of healthy liver cells. The scarred tissue blocks blood flow through the liver. It prevents the liver from processing nutrients, filtering toxins, and making substances your body needs.
  • Liver fibrosis—This occurs when the liver tries to repair damaged tissue; the repaired tissue is fibrous and prevents the liver from functioning properly.
  • Liver steatosis—Another name for fatty liver disease, a buildup of fat in the liver, leading to inflammation and liver scarring.

Long-Term Effects of Alcohol on the Pancreas

A heavy intake of alcohol can lead to inflammation of the pancreas (pancreatitis). Pancreatitis is a severe, painful disorder that has the potential to be life-threatening. The pancreatic cells break alcohol down into toxic byproducts, damaging the pancreas and its digestive enzymes. 2 These enzymes, which usually function to help break down and digest food, can end up digesting the pancreas tissue.

Wernicke-Korsakoff syndrome (WKS)

Wernicke-Korsakoff syndrome (WKS) is a memory disorder associated with alcohol misuse resulting from vitamin B1 (thiamine) deficiency. Thiamine is essential for the proper function and development of all body tissues, including your brain. Nearly 80% of people with alcohol use disorder are deficient in thiamine.3

Wernicke-Korsakoff syndrome is a chronic condition that makes it difficult for you to learn new things and remember the details of your daily life.3 WKS causes damage to nerve cells in the brain and spinal cord; the disorder can cause symptoms such as:3

  • Disorientation
  • Amnesia
  • Tremor
  • Vision problems
  • Coma

WKS may lead to a long-term disease called Korsakoff’s psychosis. Korsakoff’s psychosis affects the ability to learn and remember old and new information.

Other Adverse Effects of Alcohol

In addition to detrimental health effects, alcohol can lead to changes in behavior and relationships, including:

  • Accidents and injuries
  • Increase in high-risk behaviors, such as operating vehicles while intoxicated or having unprotected sex
  • Loss of personal items (e.g., loss of a wallet or mobile phone)
  • Unplanned time off school or work
  • Alcohol-related legal problems
  • Strain on interpersonal relationships

2. Benzodiazepines

Benzodiazepines (“benzos”), also called minor tranquilizers, are hypnotic sedative drugs; they slow down messages traveling from the brain to the body. They are often prescribed to control seizures, treat anxiety and insomnia, and relieve muscle spasms and stress.15

Benzodiazepines are commonly misused for their sedative effects, for a “high,” or to help “come down” from the effects of stimulants (e.g., cocaine or amphetamines). There are many risks associated with benzodiazepine misuse, particularly with long-term use.

Common types of benzodiazepines include:

Benzodiazepines are associated with substance use disorder (SUD) and withdrawal symptoms, even with short-term use. The potential risks of this drug are why benzodiazepines are not the first option for treating insomnia, anxiety, or other health concerns.1 These drugs are recommended for short-term use as long-term use can increase the risk of severe side effects and drug addiction. Doctors generally also include a period where they gradually reduce the dose before stopping it in their prescription to minimize potential withdrawal. Benzodiazepines can cause overdose, particularly when used with alcohol or other drugs.

Take benzodiazepines only as prescribed. Long periods of benzodiazepine use increase the risk of tolerance, addiction, and withdrawal symptoms, but even when used for a short period, benzodiazepine side effects can include:8

  • Coordination problems
  • Difficulty focusing
  • Drowsiness
  • Memory problems
  • Slower reaction time

Severe side effects associated with long-term use of benzodiazepines include: 8

  • Severe drowsiness
  • Confusion
  • Memory loss
  • Slurred speech
  • Slow heart rate
  • Trouble breathing
  • Muscle weakness and coordination problems
  • Seizures or convulsions
  • Coma

Many of the side effects of benzodiazepines can increase the risk of accidents. It is not recommended that someone with a benzodiazepine prescription operate motor vehicles until they know how the medication affects them. Driving while under the influence of benzos is equivalent to driving with an alcohol blood level above the legal limit in the United States and can result in a DUI.8

Perhaps the most dangerous risk of misusing benzodiazepines is the potentially life-threatening side effects associated with combining benzos with other drugs or alcohol. Mixing benzodiazepines with opioids or alcohol increases the depressant effects of benzodiazepines. An overdose of benzodiazepines can be life-threatening.9

3. Cough Medicine

Cough medicine has become popular as a form of drug use, particularly with the younger generation. The drugs available in many types of cough medicine are relatively inexpensive and easy to access compared to other medications.

One popular drug, comprised of prescription cough syrup containing codeine—an opioid—and promethazine hydrochloride—an antihistamine—is called lean. Lean, also called purple drank, is often mixed with a beverage such as alcohol or soda. Serious, life-threatening side effects can occur from the misuse of drugs like codeine and promethazine particularly when mixed with alcohol.

Side effects of the promethazine component of lean may include:

  • Arrhythmias, or abnormal heart rhythm
  • Hypotension, or low blood pressure
  • Hallucinations
  • Seizures
  • Severe breathing problems

Side effects of the codeine component of lean may include:13

  • Redness of the skin (e.g., arms, legs, and upper chest)
  • Dizziness
  • Shortness of breath
  • Cardiac arrest
  • Brain damage

Side effects of lean mixed with alcohol or other depressants may include:3

  • Hypotension
  • Respiratory depression causing slow or shallow breathing that may stop
  • Sleepiness
  • Stupor
  • Coma
  • Sudden death

Other types of over-the-counter cough and cold medications contain the ingredient dextromethorphan, which is a cough suppressant. At recommended doses (i.e., 15 mg to 30 mg), dextromethorphan is generally safe to use. However, taking too much dextromethorphan to get high can have adverse short-term and long-term effects on your brain and body.

Dextromethorphan is in the category of substances called dissociative drugs. Dissociative drugs may cause you to feel detached from your body or reality. Short-term effects of dissociative drugs, including dextromethorphan, worsen at higher doses and may include:10

  • Confusion
  • Difficulty with coordination
  • Disorientation
  • Feeling disconnected from yourself or reality
  • Feelings of panic, fear, anxiety, or paranoia
  • Hallucinations
  • High body temperature
  • Increased blood pressure and heart rate
  • Loss of memory
  • Numbness
  • Rapid breathing
  • Respiratory depression that becomes life-threatening when mixed with other depressants, such as alcohol or benzodiazepines
  • Seizures
  • Warped sensory perceptions (e.g., becoming unable to identify food types by taste)

4. Methamphetamine

Methamphetamine, commonly called “meth,” is a highly addictive stimulant drug that excites the central nervous system. According to a 2017 National Survey on Drug Use and Health (NSDUH), “Methamphetamine remains one of the most commonly misused stimulant drugs in the world.”11

Common names for methamphetamine include:11

  • Blue
  • Crystal
  • Ice

Methamphetamine use is associated with many dangers, including severe physical and psychological impacts, such as:11

  • Damage to the heart and blood vessels
  • Damage to nerves in the brain
  • Increase risk of infectious disease when meth is used intravenously with nonsterile needles (e.g., HIV and hepatitis)
  • Alteration in brain structure and function (e.g., memory loss, impaired decision making, and an impairment in suppressing counterproductive behaviors)

As a stimulant, methamphetamine can have immediate side effects, including:11

  • Decreased appetite
  • High blood pressure
  • High body temperature
  • Hyperactivity
  • Inability to sleep
  • Rapid breathing
  • Rapid or irregular heartbeat
  • Seizures

People who misuse methamphetamine long-term often experience many disturbing symptoms, some of which can last for months or even years after a person stops using meth. 11 For example, psychotic features caused by methamphetamine use could include hallucinations, such as the sensation of bugs crawling under the skin. Spontaneous methamphetamine psychosis, such as hallucinations, has been known to recur in response to stress in those who previously experienced psychosis with meth use. 11

Chronic methamphetamine use can lead to long-term adverse effects, including tolerance and drug addiction. Other long-term adverse effects of methamphetamines include:11

  • Anxiety
  • Changes in brain structure affecting memory and emotions
  • Confusion
  • Difficulty learning
  • Memory loss
  • Excessive weight loss
  • Psychotic symptoms (e.g., paranoia, delusions, or hallucinations)
  • Impaired motor activity
  • Skin sores
  • Tooth decay and tooth loss
  • Behavioral changes

Some adverse brain effects can last longer than a year after a person stops using methamphetamine. Additionally, a history of methamphetamine use increases the risk of stroke and Parkinson’s disease.11

Meth misuse can be treated or prevented with specific modalities, such as behavioral treatment, medication, and medical treatment to address long-term medical issues.

5. Opioids

The natural form of opioids is derived from the opium poppy plant; prescription opioids can be naturally derived or manufactured in labs. Opioids are considered one of several types of narcotic drugs. Opioids induce pain relief and sedation and are often prescribed to treat acute and severe pain, severe cough, or diarrhea.

Opioids can make a person feel highly relaxed, inducing a euphoric “high,” making this considered to have a high risk of misuse. Heroin, one of the most dangerous drug addictions globally, has no medical or therapeutic use unlike many other opioids which are prescription medicines in the U.S.12

Examples of opioids include heroin and the following prescription medications:

Your health care provider may prescribe short-term opioids, such as after an accident or surgery. However, even with short-term use, opioids can have dangerous side effects, including the following:12

  • Confusion
  • Constipation
  • Drowsiness
  • Nausea
  • Slowed breathing

When the breathing slows due to opioid misuse, the brain does not receive enough oxygen. Long-term effects of diminished oxygen supply to the brain can include coma, permanent brain damage, and death.12 Other long-term side effects of long-term opioid use include:13

  • Decreased blood pressure and heart rate
  • Disordered breathing during sleep
  • Immune system suppression
  • Increased risk of falls and injuries
  • Increased risk of heart attack or heart failure
  • Infertility
  • Low testosterone levels in men
  • Osteoporosis, or decreased bone density, in women
  • Severe constipation
  • Sexual dysfunction

Opioids are highly addictive drugs with severe side effects that can be life-threatening. If you or someone close to you is misusing prescription opioids or heroin,  seek professional help.

Drug addiction can happen to anyone. If you or someone you love is struggling with an addiction, call 800-681-1058 (Info iconWho Answers?) now.


  1. K. National Health Service. (2018, August 21) Risks, Alcohol misuse.
  2. National Institute on Alcohol Abuse and Alcoholism. Alcohol’s Effect on the Body.
  3. National Institute on Alcohol Abuse and Alcoholism. (2004). Alcohol’s Damaging Effects on the Brain.
  4. Mayo Clinic. (2020, October 27). Alcoholic hepatitis.
  5. Cleveland Clinic. (2020, November 1). Cirrhosis of the Liver.
  6. Bataller R., & Brenner, D. (2005, February 1). Liver fibrosis. The Journal of Clinical Investigation, 115(2), 209-218.
  7. Nassir, F. R. (2015, March 11). Pathogenesis and Prevention of Hepatic Steatosis. Gastroenterology & Hepatology, 11(3), 167-175.
  8. Johnson, B., & Streltzer, J. (2013, August 15). Risks Associated with Long-Term Benzodiazepine Use. American Family Physician, 88(4), 224-225.
  9. Pomerantz, J. M. (2007, August 1). Risk Versus Benefit of Benzodiazepines. Psychiatric Times, 24(7).
  10. National Institute on Drug Abuse. (2020, June 02). What Are the Effects of Common Dissociative Drugs on the Brain and Body?
  11. National Institute on Drug Abuse. (2019, October 03). Methamphetamine Research Report..
  12. National Institute on Drug Abuse. (2021, June 01) Presction Opioids
  13. Baldini A, Von Korff M, Lin EHB, (2012, June 14). A Review of Potential Adverse Effects of Long-Term Opioid Therapy: A Practitioner’s Guide. The Primary Care Companion for CNS Disorders.
  14. Foundation For A Drug-Free World. What Is Alcohol?
  15. Alcohol and Drug Foundation. (2021, July 16).