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Illicit Drugs and Alcohol Interactions

Medically reviewed by Leigh Ann Anderson, PharmD. Last updated on March 1, 2022.

Drinking and Illegal Drugs: A Dangerous Mix

The use of dangerous, illegal drugs is a concern by itself, but adding alcohol to the equation can result in hazardous, or even deadly, consequences. Those who abuse drugs, such as heroin, methamphetamine, or cocaine, tend to use more than one drug at a time, including alcohol. Drug users combine illegal drugs with other drugs or alcohol in an attempt to intensify the "high" that is experienced with either drug alone.

If you use choose to use illicit drugs, you should NOT drink alcohol, as the results are often unpredictable. Controlled studies to evaluate these drug-drug interactions are often lacking. Alcohol can dangerously boost the effects of these drugs and may increase your risk for slowed or stopped breathing, mental clouding, impaired driving and decision making, and injury. For drugs that have a stimulant action, the effects of alcohol may be blocked2, leading you to believe you can drink additional alcohol or "binge-drink".

Other effects may include: aggravation of withdrawal symptoms, serious heart effects like a heart attack, damage to the liver, mood and behavior alterations, and birth defects.

Mechanisms of drug interactions between alcohol and illicit drugs can vary. These interactions involve a complex network of effects on brain neurotransmitters (nerve chemicals) such as GABA, dopamine, glutamate, and others. The actions can either be pharmacokinetic (for example, alcohol interference with the drug’s metabolism), pharmacodynamic (changing or being additive to the drug mechanisms or side effects), or a specific mechanism related to the individual drug.2

Examples of illegal drugs often combined with alcohol include the following:1, 2


A particularly concerning, yet often unknown interaction between alcohol and cocaine has been reported.1,2,3

  • The human liver combines cocaine and alcohol and manufactures a third substance, cocaethylene, that intensifies the euphoric effect of cocaine, but may increase the risk of stroke and sudden death. Toxicity to the heart, liver, and other organs can occur. Heart rate, blood pressure, body temperature, and hormones such as cortisol rise.
  • Cocaethylene is much more potent than cocaine or alcohol alone and may stay in the system longer. It is more lethal than cocaine.2 The mechanism appears to involve alcohol blockage (inhibition) of enzymes needed to break down cocaine, leading to accumulation of the drug. Alcohol can also suppress first pass metabolism and elimination of cocaine from the body.
  • The interaction between cocaine and alcohol has been identified a common two-drug combination that results in drug-related deaths, including motor vehicle fatalities.1 Autopsies often identify brain hemorrhage, stroke or other adverse heart events.4

Gamma hydroxybutyrate (GHB)

The effects of alcohol on GHB depend upon the blood levels of alcohol, and whether it is chronically consumed on a daily basis or just occasionally. Alcohol and GBH compete for a liver enzyme used break them down for excretion from the body (CYP2E1).

  • Acute alcohol use, depending on its concentration, can reduce GBH break down in the body and increase GHB levels in the blood.
  • Chronic alcohol consumption (drinking most days in large amounts) increases the activity of the CYP2E1 enzyme, leading to a decrease in GHB concentrations.

The side effects that can occur depend upon the street product and the individual user, and this is one reason why GHB is a very dangerous drug.2

  • CNS: sedation, dizziness, nystagmus, aggression, impaired judgement, hallucinations, coma.
  • Heart effects: slowed heart rate, orthostatic hypotension (lowered blood pressure upon standing)
  • Respiratory: apnea, respiratory depression


Marijuana (cannabis) is probably the most common recreational drug combined with alcohol. Studies also show that about 58% of adolescent drinkers also use cannabis.2 Although marijuana is legal as a recreational drug and/or to treat medical conditions in many U.S. states, it is still considered an illegal Schedule I drug by the U.S. government.

Delta-9-tetrahydrocannabinol (THC) is the primary component of cannabis that leads to the "high" experience. These acute effects occur via the endocannabinoid type 1 (CB1) receptor.2

  • Alcohol use with marijuana leads to increased THC absorption and plasma levels, and decreased blood-alcohol levels.2
  • Using marijuana with alcohol will boost effects like dizziness, drowsiness, confusion, and difficulty concentrating.
  • Driving can be especially hazardous due to an impairment in thinking, judgment, and motor coordination. You should also avoid operating machinery or engaging in potentially hazardous activities if you use any illicit drug, marijuana or alcohol.


Alcohol abuse and methamphetamine use often occur together. Over 70% of people diagnosed with amphetamine dependence also have an alcohol use disorder.2

  • When methamphetamine is combined with alcohol, decreased metabolism and excretion of methamphetamine occurs. Higher blood levels of methamphetamine may occur.
  • Heart rate, oxygen consumption, and blood pressure all rise. Nervous system stimulation may further elevate.
  • Those who combine alcohol and methamphetamine (or Ectasty, Molly) may feel euphoric and less sedated but their actual ability to perform is impaired by the effect of alcohol.

Types of Drug Interactions With Alcohol


  1. Jones A. Forensic Drug Profile: Cocaethylene. J Anal Toxicol. 2019 Apr 1;43(3):155-160. doi: 10.1093/jat/bkz007. Accessed March 1, 2022.
  2. Singh A. Alcohol Interaction with Cocaine, Methamphetamine, Opioids, Nicotine, Cannabis, and γ-Hydroxybutyric Acid. Biomedicines. 2019 Mar; 7(1): 16. doi: 10.3390/biomedicines7010016 Accessed March 1, 2022.
  3. National Institute on Drug Abuse (NIDA). NIH. Drug Facts. What is Cocaine? Updated July 2018. Accessed March 1, 2022 at
  4. Jones A. Forensic Drug Profile: Cocaethylene. Journal of Analytical Toxicology. 2019: 43; 155–160. Accessed March 1, 2022 at

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.