The effects of illegal drugs will always be unpredictable. Generally, when you mix them with alcohol they’re exaggerated in some way, which can result in anything from nausea to heart failure. Best advice is to completely steer clear of illegal drugs, especially with alcohol.

What happens in the body? 

Alcohol is a depressant. Combine it with a stimulant, such as cocaine, and the two drugs compete with each other. The depressant drug tries to slow the brain/central nervous system down, while the stimulant tries to speed it up – putting your brain/central nervous system under great pressure. Combine alcohol with another depressant drug, heroin for example, and the effect they each have of slowing your central nervous system will be multiplied, and you risk your body shutting down altogether.1

With no quality control in the world of illegal drugs, you can never be 100% sure of exactly what’s in the substance you’re taking. It could be cut with other cheaper drugs such as tranquilisers or even toxic substances such as drain cleaner. Add alcohol into the mix and you’ve got a potentially lethal cocktail.
If you’re under the influence of drugs, you’re less likely to make considered decisions about how much alcohol you drink. So you also put yourself at risk of alcohol poisoning and longer-term health effects of alcohol such as heart disease and cancer.
Here are some facts about individual drugs and what can happen when you mix them with alcohol. 

Alcohol and marijuana (cannabis) 

If you use cannabis and alcohol together, the results – both physical and psychological – can be unpredictable. Having alcohol in your blood can potentially cause your body to absorb the active ingredient tetrahydrocannabinol (THC) faster. This can lead to the cannabis having a much stronger effect than it would normally have.2
Physically, you can experience dizziness, nausea and vomiting. Psychological effects include panic, anxiety or paranoia. Skunk, a term for stronger types of cannabis, can pose even greater risks, because it may contain three times as much THC.3
There’s a serious long-term risk to your health too. Cannabis is usually smoked with tobacco, which can cause cancer. Tobacco and alcohol work together to damage the cells of the body, multiplying the damage. Alcohol makes it easier for the mouth and throat to absorb the cancer-causing chemicals in tobacco4.

Alcohol and cocaine 

A common but particularly dangerous partnership, alcohol and cocaine together increase the risk of heart attacks and fits and even sudden death. The two drugs interact to produce a highly toxic substance in your liver called cocaethylene. It can increase the depressive effects of alcohol, making your reaction to the cocaine stronger. You’re also more likely to be aggressive with cocaethylene in your system.
Cocaethylene takes longer to get out of your system than either the alcohol or the cocaine, subjecting your heart and liver to a longer period of stress. Mixing alcohol and cocaine can be fatal up to 12 hours after you’ve taken it.5 6

Alcohol and ecstasy (MDMA) 

It’s possible that alcohol will deaden the ‘high’ you feel from ecstasy while the drugs are in your system7. But the next day, when you ‘come down’, you’ll feel much worse if you’ve been drinking alcohol. A severe hangover is one of the milder side-effects of combining these drugs though, together they can be deadly.
Ecstasy dehydrates you. So does alcohol. You risk overheating and becoming dangerously dehydrated when you combine the two. Alcohol is involved in most ecstasy related deaths, many of which are from heatstroke after people have danced for long periods of time in hot clubs without replacing the fluids they’ve lost by drinking water.
As alcohol is a diuretic, which means it makes you go to the loo a lot and sweat more, it’s even harder to keep enough fluid in your body when you drink it while on ecstasy8. There’s also a greater strain on your liver and kidneys when you combine the two drugs. And, as with many other combinations, you’re likely to experience nausea and vomiting.

Alcohol and amphetamines

The effects of amphetamines, often called ‘speed’, are very much like an adrenalin rush. When you take it, your breathing, blood pressure and heart rate speed up. Like ecstasy, speed can also increase your body temperature and cause dehydration – which is heightened when you add alcohol. As speed already puts pressure on your heart, if you add alcohol, that pressure can be fatal.
Alcohol can intensify your emotions and make you lose your inhibitions. So can speed. Combine the two and you may end up behaving in a way you seriously regret.
Under the influence of speed you may feel more confident or energised, but you can easily become anxious, paranoid or aggressive, particularly when you put alcohol in the mix.9 You don’t feel the full effects of alcohol until the speed has worn off. Mixing the two means you can drink dangerous amounts without realising.

Alcohol and heroin

Alcohol with heroin is one of the most dangerous combinations of drugs. ‘Downers’ like heroin slow down your heart rate and breathing. When combined with another ‘downer’ such as alcohol you’re basically doubling up and putting yourself at risk of overdosing.
The National Treatment Agency for Substance Misuse says that even small amounts of alcohol seem to lower the amount of heroin needed to fatally overdose. Around three quarters of people who die from heroin overdoses have drunk alcohol10.

Alcohol and ‘legal highs’

Previously known as ‘legal highs’, drugs such as meow meow actually became illegal in 2010 when they were classified as class B drugs. A powerful stimulant, drugs such as meow meow are part of the cathinone family, a group of drugs that are closely related to the amphetamines. They’re derived from the plant khat, commonly used as a stimulant in East Africa and have similar effects to ecstasy and speed. These drugs can over stimulate circulation, damaging the heart, speed up the nervous system and cause fits. They can also make you anxious and paranoid. As with any drug that gives a ‘high’, combine them with alcohol and you’re at risk of everything from nausea and vomiting to coma and death.11 12

More information 

For more information on drugs, contact the National Drugs Helpline – Talk to Frank
Freephone 0800 77 66 00


(1) Talk to Frank. Why is mixing drugs dangerous?. Available at:
(2) National Cannabis Prevention Information Centre website. Mixing cannabis and alcohol. Available at:
(3) Royal College of Psychiatrists. 'Cannabis and mental health'. Available at:
(4) Cancer Research UK website. How alcohol causes cancer. The Information Standard member organisation. Last reviewed: 23/3/15. Available at:
(5) Drinking with Charlie website. So what?. Available at:
(6) Talk to Frank website. Cocaine. Available at:
(7) Terrence Higgins Trust website. Drug Fucked: Alcohol. The Information Standard member organisation. Last reviewed: 28/10/11 Available at:
(8) DrugScope website. Why do people die after taking ecstasy?. Available at:
(9) EYPDAS website, Amphetamines. Available at:
(10) National Treatment Agency for Substance Abuse. HS, 'Does the combined use of heroin or methadone and other substances increase the risk of overdose?', 2007. Available at:
(11) Talk to Frank website, Mephedrone. Available at:
(12) DrugScope website. Mephedrone. Available at: