What Drugs Are Dangerous to Mix With Alcohol?

The most dangerous things to mix with alcohol are other central nervous system depressants: GHB, ketamine, benzodiazepines and opioids. Their sedating effects stack and can suppress your breathing to the point of death. Alcohol is itself a depressant, and most fatal “overdoses” at parties are not one substance but a combination with alcohol somewhere in it. If you remember one thing from this page: pick one depressant for the night, or none.

The second high-risk category works differently. With stimulants like cocaine, alcohol does not sedate you, it builds a longer-lasting and more cardiotoxic metabolite while you feel fine.

Why stacking is worse than adding

Your brainstem runs your breathing without asking you. Several drug classes suppress that drive, each through a different receptor:

• Alcohol: GABA-A and NMDA
• GHB and GBL: GABA-B and GHB receptors
• Benzodiazepines: GABA-A
• Opioids: mu-opioid receptors
• Ketamine: NMDA, at high doses

Because they hit different systems, combining them does not add up, it compounds. A dose of GHB that would put you to sleep on its own can stop your breathing once alcohol is also pressing on the same brainstem circuits. That is why polydrug depressant deaths so often involve people who did not take a large amount of anything.

The combinations that kill

GHB and alcohol

Probably the most dangerous common combination there is. GHB has a steep dose-response curve, meaning a small increase in dose produces a large jump in effect, and alcohol shifts that curve. Busardò and Jones’s 2023 review of GHB pharmacology and toxicology describes synergistic central nervous system and respiratory depression, unconsciousness, and vomiting with a high aspiration risk. Because GHB is dosed in milliliters and its effects are this alcohol-sensitive, there is no reliably safe amount to combine. Our GHB and alcohol guide has the full picture.

Benzodiazepines and alcohol

Xanax, Valium, Klonopin and alcohol all enhance GABA-A signaling, and together they produce heavy sedation and respiratory depression. CDC surveillance data found alcohol involved in nearly 1 in 5 benzodiazepine overdose deaths. What makes it worse is that both drugs wreck memory and judgment, so accidental redosing is likely, and that is a frequent mechanism in blackout deaths. If you use a benzo to come down or sleep after a night out, the alcohol should be metabolized first.

Ketamine and alcohol

Ketamine on its own rarely stops breathing, but with alcohol the sedation deepens and the risk of respiratory depression, vomiting and aspiration climbs. The bigger practical danger is a k-hole while drunk: profound dissociation and immobility leaves you unable to protect your airway if you throw up. See our ketamine and alcohol guide.

Opioids and alcohol

Heroin, oxycodone, fentanyl, any of them plus alcohol is the classic fatal respiratory depression combination. The current supply makes this worse than it used to be, because stimulants and pressed pills are frequently contaminated with fentanyl. If you are drinking and using anything that did not come from a pharmacy, test it for fentanyl first and carry naloxone. One line on a strip is positive, two lines is negative, and strips are single use, one per sample. Naloxone reverses opioids only, not alcohol, GHB or benzo sedation.

Cocaine: awake, and still in danger

Alcohol plus cocaine is a different shape of risk. It does not sedate you, so people feel fine and drink more, because cocaine masks how impaired they are. The real problem is metabolic.

When cocaine and ethanol are in the liver together, some cocaine is converted into cocaethylene, a cardiotoxic metabolite with a longer half-life than cocaine itself, so the cardiovascular strain outlasts the high. A 2022 study of emergency department patients with acute drug overdose links it to heart attack, arrhythmia and sudden cardiac death, and it happens in young, otherwise healthy people more often than most realize. Because you feel more sober than you are, the behavioral risks rise too: driving, more drinking, more cocaine. Full detail in our cocaine and alcohol guide.

If someone goes down

Someone who has been drinking becomes unresponsive after any drug:

• Call emergency services. Most areas have Good Samaritan laws that protect you from drug possession charges when you call about an overdose.
• Put them on their side, in the recovery position, so they cannot choke on vomit. For a sedated person this is the single most useful thing you can do.
• Do not leave them to sleep it off. Sedation from stacked depressants deepens into respiratory arrest.
• Give naloxone if opioids are even possible. It cannot hurt if you are wrong. It reverses the opioid part and nothing else.
• Stay and watch their breathing until help arrives.

Before the night, not during it

Look up any specific combination in our drug interaction checker while you are still sober enough to change your mind. Two things are worth holding onto: alcohol makes almost every drug interaction more dangerous rather than less, and knowing what is actually in a substance matters as much as knowing what you are mixing it with.

Sources

• Cappetta M, et al. Cocaethylene cardiotoxicity in emergency department patients with acute drug overdose, 2022. PMID 36000306
• Busardò FP, Jones AW. GHB pharmacology and toxicology: acute intoxication, dependence, withdrawal, and related risks, 2023. PMID 36837798
• Jones CM, Paulozzi LJ, Mack KA (CDC). Alcohol involvement in opioid pain reliever and benzodiazepine drug abuse-related emergency department visits and drug-related deaths, United States, 2010. MMWR, 2014. PMID 25299603