Alcohol and Cannabis: Effects, Risks and Mixing

Using alcohol and cannabis together is riskier than consuming either substance alone. The combination can significantly increase drowsiness, nausea, dizziness, confusion, anxiety, loss of control and inability to drive. What is particularly problematic is that one’s own assessment often gets worse while the actual impairment increases.

Many people underestimate mixed consumption because both substances have a known effect individually. When interacting together, however, they change perception, reaction time, coordination and judgment to a greater extent. Alcohol can also affect THC absorption, making cannabis subjectively stronger or more unpredictable. The safest decision remains: do not combine alcohol and cannabis and do not drive after consumption.

First things first

• Mixed consumption increases risks: Alcohol and cannabis can increase drowsiness, confusion, nausea and problems with concentration.
• THC can have a stronger effect: Studies show that alcohol can increase the THC concentration in the blood.
• Driving is particularly dangerous: Both substances impair reaction, coordination and decision-making confidence; together the risk is higher.
• Edibles are tricky: Edible cannabis has a delayed effect. Alcohol can cause warning signs to be recognized too late.
• Take emergency signs seriously: Unconsciousness, difficulty breathing, seizures, severe confusion or chest pain are reasons for immediate medical attention.

How do alcohol and cannabis work individually?

Alcohol has a depressant effect on the central nervous system. Depending on the amount, it can disinhibit, lengthen reaction times, worsen coordination, increase willingness to take risks and cause nausea or impaired consciousness.

Cannabis works primarily via the endocannabinoid system. THC can trigger relaxation, altered perception, euphoria and heightened sensory impressions, but can also promote anxiety, panic, racing heartbeat, concentration problems or psychotic symptoms. You can find more basic information in the articles on cannabis, THC and the risk of psychosis when using cannabis.

What happens when alcohol and cannabis work together?

When consumed in mixed form, two psychoactive effects come together. The result is not simply “alcohol plus cannabis,” but can be much more unpredictable. Users particularly often report severe drowsiness, confusion, slowed thinking, dizziness, nausea and difficulty realistically assessing their own condition.

A study in the journal Drug and Alcohol Dependence showed that ethanol can increase THC levels in blood plasma. A review article on co-use of alcohol and cannabis also describes that simultaneous consumption can be associated with increased effects and more negative consequences.

Typical symptoms of mixed consumption

The effect depends on the dose, sequence, form of consumption, body weight, tolerance, sleep, food, psychological state and mixed consumption with other substances. Common complaints include:

• severe drowsiness or sleepiness
• Dizziness, balance problems and coordination problems
• Nausea, vomiting or circulatory problems
• Confusion, problems concentrating or memory lapses
• Fear, panic, paranoia or hallucinations
• Rapid heartbeat, chest tightness or severe discomfort
• Misjudgment of one’s own ability to drive or resilience

Colloquially, an unpleasant cannabis high with nausea, dizziness or panic is often referred to as “greening out”. Alcohol can worsen such conditions because it puts additional strain on coordination, stomach and circulatory system.

Why do you get sick more quickly when combining?

Alcohol irritates the stomach, circulatory system and vestibular system. Cannabis can also affect cognition, circulation and nausea. Together, this can cause the body to react more severely: sweating, paleness, dizziness, nausea and vomiting are typical warning signs.

What is particularly risky is that vomiting can be dangerous if you are extremely light-headed. Anyone who is barely responsive, sleeps heavily or vomits repeatedly should not be left alone.

Alcohol first or cannabis first: Does the order make a difference?

The order can change perception, but does not make mixed consumption safe. Drinking alcohol first can decrease self-control. As a result, more cannabis is often consumed later or its effects are underestimated. If cannabis is consumed first, alcohol can later have a more disinhibiting or physically stressful effect.

drugcom.de reports on research on the influence of the timing of mixed consumption and makes it clear that the combination can be associated with more undesirable effects. There is no safe order.

Edibles and alcohol: particularly difficult to assess

When cannabis is smoked or vaporized, the effects usually occur more quickly. With edibles, it takes significantly longer for the effect to become noticeable. Anyone who drinks alcohol during this waiting period may misjudge the effect and refill it too early. This increases the risk of overdose, panic, vomiting and loss of control.

Especially with edibles, delay is a major problem. Alcohol makes this delay more dangerous because patience, judgment and self-control decrease.

Risk in road traffic

Alcohol and cannabis both impair the skills that are critical to driving: reaction time, attention, coordination, lane keeping, distance judgment and risk assessment. Together the impairment is particularly critical.

A review of cannabis, alcohol and driving performance shows that the combination is particularly problematic for driving ability. Another study on simultaneous alcohol and cannabis consumption in traffic links simultaneous consumption with risky driving under the influence of both substances. For German traffic topics, the contributions THC limit in the car, CBD and driving and drug tests by the police are also suitable.

Psychological risks: fear, panic and loss of control

Alcohol can lower inhibitions and make risky decisions easier. Depending on the dose and the person, cannabis can calm you down, but can also trigger anxiety, paranoia or psychosis-like symptoms. Together, inner control can be lost more quickly: thoughts race, the environment appears threatening, and simple decisions are difficult.

Anyone who already has anxiety disorders, experiences with psychosis, bipolar symptoms or a strong family history should be particularly careful. Mixed consumption can exacerbate existing psychological risks. In the event of acute confusion, danger to yourself or others, medical help is necessary.

Long-term consequences of regular mixed consumption

Regular mixed consumption can stabilize consumption patterns: alcohol lowers inhibitions, cannabis is used for relaxation, and both substances are increasingly linked to one another. This can make it more difficult to quit and increase the risk of problematic consumption.

Possible long-term stresses include sleep problems, difficulty concentrating, lack of motivation, increased mood swings, conflicts, risky driving and a higher risk of addiction. Anyone who notices that alcohol and cannabis almost always go together should take this seriously as a warning signal. Helpful in-depth information includes cannabis withdrawal and withdrawal as well as controlled drinking.

What to do if the combination works badly?

If someone experiences severe symptoms after drinking alcohol and cannabis, the first thing that helps is rest, a safe environment, no further refills, water in small sips and a sober person who stays with it. The person should not be left to sleep alone if they are unresponsive or are vomiting repeatedly.

Immediate medical attention is important if you experience loss of consciousness, difficulty breathing, seizures, chest pain, severe confusion, persistent vomiting, bluish lips, very slow breathing, or danger to yourself. If you are unsure, it is better to get help than to underestimate poisoning.

Conclusion: Mixed consumption is not a predictable combination

Alcohol and cannabis don’t just “intensify the high”. They can unpredictably deteriorate control, coordination, circulation, anxiety levels and driving ability. High quantities, edibles, little experience, psychological pre-existing conditions and any participation in traffic are particularly risky.

The clear guidance is: If you want to stay safe, don’t combine alcohol and cannabis. Anyone who has already consumed should not drive, do not refuel and take warning signs seriously.

Sources and further information

CDC: Alcohol