Cannabis or alcohol: Which is more harmful? The comparison

In short: cannabis or alcohol – which is more harmful?

The question "cannabis or alcohol – which is more harmful?" first requires a definition. At the individual level, this includes acute poisoning, organ damage, mental health consequences, addiction, and accident risks. At the societal level, road accidents, violence, treatment costs, work absences, and harm to relatives are also included. A substance can therefore cause very significant harm on a population level, even though individual risk depends heavily on the respective consumption pattern.

A frequently cited study by David J. Nutt, Leslie A. King, and Lawrence D. Phillips evaluated 20 substances based on 16 criteria in 2010. These included mortality, addiction, physical harm, and harm to other people, among others. In this multicriteria expert comparison, alcohol received 72 out of 100 harm points, while cannabis received 20.

The full source is: Nutt DJ, King LA, Phillips LD: "Drug harms in the UK: a multicriteria decision analysis". The Lancet. 2010;376(9752):1558–1565. DOI: 10.1016/S0140-6736(10)61462-6.

The study is important, but its limitations should be mentioned: It was based on an expert model, created for Great Britain, and published in 2010. It is therefore not an up-to-date universal ranking of all drug risks. However, its general finding regarding the high societal harm caused by alcohol is supported by more recent public health data. 

The WHO continues to describe alcohol as a toxic, psychoactive, and addictive substance associated worldwide with millions of deaths and more than 200 health consequences.

Another often overlooked factor is availability and societal normalization. The extent of harm caused by a substance on a population level depends not only on its pharmacology, but also on how many people consume it, how frequently it is consumed, and in what situations. A societal comparison of harm is therefore not the same as asking which substance is riskier for a specific person in a specific quantity.

The WHO lists associations with cancers of the mouth, throat, esophagus, liver, bowel, and female breast, among others.

The following may be particularly affected:

• Liver and pancreas
• Cardiovascular system
• Brain and nervous system
• Gastrointestinal tract
• the risk of several types of cancer

Very high amounts of alcohol can also severely impair consciousness and protective reflexes. Vomiting while unconscious, breathing problems, hypothermia, heart rhythm disturbances, and seizures can make severe alcohol poisoning life-threatening.

A major analysis by the GBD 2020 Alcohol Collaborators examined data from 204 countries and territories for the years 1990 to 2020 and considered 22 health consequences. The benefit-risk balance was particularly unfavorable for younger adults.

Full source: GBD 2020 Alcohol Collaborators: "Population-level risks of alcohol consumption by amount, geography, age, sex, and year: a systematic analysis for the Global Burden of Disease Study 2020". The Lancet. 2022;400(10347):185–235. DOI: 10.1016/S0140-6736(22)00847-9.

For practical purposes in Germany, the following is now also important: 

There is no alcohol quantity that is free from health risks. The WHO, the German National Centre for Addiction Issues, and the German Nutrition Society have significantly revised or abandoned older ideas about a generally "safe" daily drinking amount. The German Nutrition Society generally recommends no alcohol or as little as possible. For healthy, non-pregnant or non-breastfeeding adults, it defines less than 27 grams of alcohol per week – approximately one to two small alcoholic drinks – as a low-risk range. Low risk does not expressly mean risk-free.

THC works differently – but not without consequences

THC particularly affects the body's own endocannabinoid system and acts primarily through CB1 receptors in the central nervous system. This can change perception, memory, reaction time, coordination, and the sense of time, among other things.

Typical acute effects can include:

• Anxiety and panic
• Disorientation and memory gaps
• Racing heart, dizziness, or nausea
• Altered perception and reaction time
• in individual cases hallucinations or psychotic symptoms

The reaction varies greatly from person to person and depends on factors such as dose, method of consumption, health status, prior experience, and mixed use.

The comparison with alcohol must remain precise here: 

While a severe alcohol poisoning can be immediately fatal, the typical acute risk profile for plant-based cannabis or THC is different. However, this does not mean that cannabis cannot cause medical emergencies or indirectly contribute to serious consequences – for example through accidents, severe psychological reactions, or risky mixed use.

The type of product is also crucial. Synthetic cannabinoids are not a stronger version of regular cannabis, but a separate class of substances. Severe poisoning and deaths have been documented for several synthetic cannabinoid receptor agonists.

Smoking also introduces combustion byproducts. Smoke-free products avoid this specific smoke exposure, but they do not eliminate the psychoactive risks. When THC is taken orally, the delayed onset of effects can also make it harder to assess the effects and the dose.

The overall societal balance does not answer every individual case. For example, someone who has consumed highly potent cannabis daily since adolescence and has a pre-existing mental health condition has a different risk profile than a healthy adult who consumes it rarely. Conversely, regular alcohol consumption is not automatically harmless even if the person never appears visibly intoxicated in everyday life.

The following are particularly relevant for individual risk:

• Early onset of consumption
• Frequent or daily consumption
• High THC concentrations
• Pre-existing mental health conditions
• Individual vulnerability and consumption patterns

Age is particularly relevant with cannabis. The German Federal Ministry of Health points out that children, adolescents, and young adults are especially vulnerable to possible psychological, physical, and social effects due to their still-developing brains until about the age of 25.

A widely cited study by Marta Di Forti and the EU-GEI research group compared 901 people with a first psychotic episode with 1,237 control subjects at eleven sites in Europe and Brazil. Daily consumption and cannabis with high THC content were particularly strongly associated with the occurrence of psychotic disorders.

Full source: Di Forti M et al.: “The contribution of cannabis use to variation in the incidence of psychotic disorder across Europe (EU-GEI): a multicentre case-control study”. The Lancet Psychiatry. 2019;6(5):427–436. DOI: 10.1016/S2215-0366(19)30048-3.

It is important to note: A case-control study does not prove that cannabis alone caused the psychosis. Other factors can also play a role. However, larger evidence syntheses now also support the link between frequent consumption, high THC concentrations, and psychotic outcomes.

An umbrella review from 2024 evaluated 32 systematic reviews and meta-analyses; another systematic review from 2025 with 99 studies found particularly consistent negative associations between highly concentrated THC products and psychosis or schizophrenia, as well as cannabis use disorders.

This makes the statement significantly more robust than a simple sentence like “Cannabis causes psychosis.” The deciding factors are consumption patterns, potency, age, and individual vulnerability.

There is no harmless alternative on the road

Both cannabis and alcohol can impair driving ability. Particularly relevant impairments include:

• Slower reaction time
• Reduced attention and concentration
• Altered perception of speed and distance
• Poorer coordination
• Additional impairments from mixed consumption

A recent systematic review and meta-analysis from 2025 evaluated 31 studies with a total of 328,388 people. The authors found evidence with low certainty that cannabis consumption may be associated with an increased risk of fatal traffic accidents and injuries in traffic accidents. At the same time, they emphasize existing uncertainties and methodological limitations of the data.

For Germany, a legal dimension is added: According to § 24a StVG, a THC limit of 3.5 ng/ml in blood serum generally applies to driving a motor vehicle. There are also special rules for novice drivers and people under 21, as well as a ban on the relevant mixed consumption with alcohol.

However, this legal value should not be interpreted as a personal “safe driving limit”. Driving ability does not depend solely on a single laboratory value. Anyone who notices an intoxicating effect or feels impaired in their reaction, concentration, or perception should not get behind the wheel.

Mixed consumption is also not a good idea: 

Experimental studies show that both alcohol and cannabis can affect relevant driving performance and that the combination can cause additional impairments.

Problematic consumption does not only begin with a diagnosed addiction. Warning signs can include increasing quantities, unsuccessful attempts to reduce, loss of control, morning consumption, memory gaps, secretive behavior, or neglecting work, relationships, and leisure activities. The sentence “I need this every evening to switch off” also deserves attention if it becomes a fixed ritual.

With regular cannabis consumption, during a break, other things can occur, including irritability, inner restlessness, anxiety, sleep problems, reduced appetite, sweating, or tremors appear. Cannabis addiction can also involve loss of control, the development of tolerance, and neglect of other areas of life.

With alcohol, the withdrawal situation is potentially more dangerous. After prolonged regular or dependent consumption, tremors, sweating, rapid heartbeat, altered consciousness, and seizures can occur. So-called cold turkey withdrawal can cause serious complications and should not be carried out without medical supervision if addiction exists.

Unconsciousness, severe breathing problems, seizures, or severe confusion are medical emergencies and require immediate help by calling 112.

The healthiest decision is not to consume alcohol or cannabis. If you do consume, you should not try to classify a substance generally as “healthy” or “harmless,” but rather look at the actual pattern: How often? How much? Why? In what situation? And what are the consequences?

With alcohol, it first helps to know the actual amount. A so-called standard drink contains approximately 10 to 12 grams of pure alcohol. This corresponds, for example, to approximately 0.3 liters of beer, 0.125 liters of wine or sparkling wine, or about 4 cl of a spirit with around 38% ABV. Accordingly, half a liter of beer already contains approximately 20 grams of pure alcohol and roughly corresponds to two standard drinks.

These standard drinks are merely intended to make quantities comparable. They do not represent a health-safe daily dose. Since 2024, the German Nutrition Society (DGE) explicitly recommends no or as little alcohol as possible and no longer classifies amounts above 27 grams per week as a low-risk range for healthy adults.

With cannabis, however, factors such as THC content, frequency of consumption, form of consumption, age, and individual reaction are important. The German Federal Ministry of Health also points out that the effects can vary considerably depending on the amount consumed, the method of consumption, the physical and psychological situation, and prior experience.

For everyday life, a few simple basic rules help:

• Do not combine alcohol and cannabis

• Do not drive a car or bicycle while intoxicated

• Do not operate machinery or dangerous equipment

• Pay attention to medications and possible interactions

• Honestly keep track of consumption amount and frequency

• If consuming regularly, consciously plan consumption-free days

Special caution also applies to medications. Alcohol can change the effect of medicines, and the German Health and Social Care Association (DHS) recommends avoiding alcohol, especially with painkillers and psychotropic medications, or clarifying interactions with a doctor or pharmacist. This also applies to sleeping pills and sedatives.

A consumption diary for a few weeks can help make quantities, situations, and triggers visible. Anyone who repeatedly crosses boundaries should not rely solely on willpower.

In Germany, there are low-threshold offers for this: The DHS addiction help directory makes it possible to search for local counseling centers. drugcom.de also offers free and anonymous online counseling; there are specialized offers for people who want to reduce or stop their cannabis consumption.

In cases of regular high alcohol consumption or suspected addiction, reduction should be medically supervised due to possible withdrawal complications.

There is no single answer to the question “Cannabis or alcohol – which is more harmful?”. The key is whether we are talking about societal harm or individual risk.

At the population level, there is strong evidence that alcohol causes greater health and societal harm. This includes, among other things:

• chronic diseases
• several types of cancer
• poisoning and accidents
• addiction
• harm to family members and society

The WHO links alcohol to more than 200 diseases and other health consequences.

However, this does not mean that cannabis is harmless. In particular, early onset, frequent use, and high THC concentrations increase certain risks. These include, among other things, addiction, impaired memory and attention, and an increased risk of psychotic disorders in predisposed individuals.

For the individual, therefore, the pattern of use is what matters most.

Daily use of high-potency products can be riskier for one person than an occasional alcoholic drink. At the same time, regular alcohol consumption can cause significant physical damage long before addiction or visible intoxication becomes apparent.

Instead of simply asking “Which substance is worse?”, five more specific questions can be more helpful:

• How much is consumed?
• How often?
• At what age?
• What pre-existing physical or mental health conditions are there?
• What effects has the use already had on daily life?

Ultimately, both apply:

Less harmful does not mean harmless.

Editorial sources

• Nutt DJ, King LA, Phillips LD. Drug harms in the UK: a multicriteria decision analysis. The Lancet. 2010;376(9752):1558–1565. DOI: 10.1016/S0140-6736(10)61462-6.

• GBD 2020 Alcohol Collaborators. Population-level risks of alcohol consumption by amount, geography, age, sex, and year. The Lancet. 2022;400(10347):185–235. DOI: 10.1016/S0140-6736(22)00847-9.

• Di Forti M et al. The contribution of cannabis use to variation in the incidence of psychotic disorder across Europe (EU-GEI). The Lancet Psychiatry. 2019;6(5):427–436. DOI: 10.1016/S2215-0366(19)30048-3.

• Groening JM et al. A systematic evidence map of the association between cannabis use and psychosis-related outcomes across the psychosis continuum. Psychiatry Research. 2024.

• High-Concentration Delta-9-Tetrahydrocannabinol Cannabis Products and Mental Health Outcomes: A Systematic Review. 2025.

• Jin A et al. Cannabis consumption and motor vehicle collision: A systematic review and meta-analysis of observational studies. International Journal of Drug Policy. 2025;142:104832.

• World Health Organization: current information on alcohol, health risks, and cancer.

• German Nutrition Society: Alcohol – intake in Germany, health and social consequences, and derived recommendations for action. Position paper 2024 and current FAQs.

• German Federal Centre for Addiction Issues: Recommendations on dealing with alcohol. Current status.

• German Federal Ministry of Health: current FAQs on the Cannabis Act and health risks.

• German Road Traffic Act § 24a: current THC limit in road traffic.