Many drinkers I know are considering switching to recreational cannabis containing THC. In fact, drinking is at a 90-year low, and Gen Z appears to be leading the way. But is cannabis with THC safer than alcohol? Both substances have been used by humans for thousands of years, yet their risk profiles differ substantially. Let’s explore. 

Lethality

Perhaps the most striking difference between cannabis and alcohol is acute toxicity — the risk of fatal overdose. Acute alcohol poisoning kills thousands of people annually in the United States, largely because alcohol has a narrow margin between an intoxicating dose and a lethal one. When blood alcohol concentration reaches high levels, alcohol suppresses the brain regions controlling breathing and heart rate, which can be fatal. The CDC reports approximately 2,200 alcohol poisoning deaths each year in the U.S. 

Cannabis, in contrast, has no established lethal dose in humans. There are no confirmed deaths from cannabis overdose in the medical literature. High doses of THC can cause severe discomfort, anxiety, and even temporary psychotic symptoms–but you won’t die from a THC overdose. 

Driving

One of the leading causes of death in the US is traffic accidents. Before I give the statistics on THC vs. alcohol, let me emphasize that no one should drive impaired, whether it is THC, alcohol, sleepiness, or any other factor including texting. Driving is dangerous enough without impairment.

Now to the facts. According to the National Highway Traffic Safety Administration (NHTSA), nearly 13,000 people died in alcohol-impaired driving traffic deaths in 2023. However, rates of alcohol-impaired driving have fallen significantly over the past decades, and death rates attributable to drunk driving have also fallen. 

The story for THC is more difficult to discern.  A recent study found that over 40% of drivers killed in fatal crashes tested positive for active THC, with average levels of 30.7 ng/mL—far above legal limits in most states. It is difficult to distinguish whether this statistic is due to correlation or if THC causes a significant number of crash fatalities. Those numbers do exceed the percentage of people who use THC, so there is something there. But, also consider that 10% had both THC and alcohol. 

Moreover, THC blood concentration doesn’t directly correlate with impairment level. Unlike alcohol, where blood levels reliably indicate impairment, THC’s relationship is complex: blood THC levels spike quickly after use but can remain detectable long after psychoactive effects subside—especially in regular users who store THC in fat tissue. Additionally, tolerance varies widely, meaning the same blood THC level produces different impairment in different people. THC from smoking or tinctures typically produces intoxicating effects for about four hours. Edibles are different, though, and are known to be longer and stronger.

Many studies have shown that the effects of THC on driving and driving-related skills are relatively small. The lore–and some scientific evidence suggests–that drivers under the influence of cannabis are aware of their impairment and attempt to compensate for it by, for example, slowing down, focusing attention and not taking risks. With the exception of edibles, THC impairment is seldom severe or long lasting. In closed course and driving simulator studies, THC’s acute effects on psychomotor performance include minor impairments in tracking, reaction time, and increased weaving. Drivers under the influence of cannabis tend to give greater distance to vehicles in front of them and tend to decrease their speed.

Organ damage

Alcohol is directly toxic to multiple organ systems. Chronic heavy drinking causes liver disease, including cirrhosis and liver failure, cardiovascular damage, including cardiomyopathy, brain damage and cognitive decline and increased cancer risk (mouth, throat, esophagus, liver, breast, and colon), among other problems. The World Health Organization estimates that alcohol contributes to over 3 million deaths globally each year.

Cannabis’s physical health impacts are less severe, but certainly not absent. Impacts include respiratory issues from smoking–though less severe than tobacco. Chronic bronchitis is common among cannabis users. There are some documented cardiovascular effects of using cannabis, notably increased heart rate, but that stops when the cannabis wears off. An elevated heart rate can be problematic for older adults and anyone with heart conditions. One challenge is that cannabis is often consumed with tobacco, which makes it difficult to assign cause. 

Cancer risk

Alcohol is classified as a Group 1 carcinogen by the International Agency for Research on Cancer — meaning there’s strong evidence it causes cancer in humans. Even moderate drinking contributes to cancer risk.

The relationship between cannabis and cancer is less clear. While smoking cannabis exposes users to carcinogens, large-scale studies have not found the same strong cancer links seen with tobacco or alcohol. Some research suggests possible protective effects of cannabinoids against certain cancers, though this remains under investigation. The cancer risk from cannabis appears to be primarily related to smoking rather than the cannabinoids themselves and, thus, one can always use edibles or tinctures to eliminate the risks from smoking. Research continues on the risks of vaping. Also, note that most cannabis users don’t smoke nearly as much plant material as tobacco users but many cannabis users do add tobacco to their cannabis. 

Brain and mental health

Both alcohol and cannabis affect the brain, but differently. Alcohol is neurotoxic. Chronic heavy use of alcohol causes persistent cognitive impairment and memory problems, brain shrinkage that is clearly visible on brain images, and thiamine deficiency that can cause Wernicke-Korsakoff syndrome, a severe memory disorder. Alcohol consumption is associated with increased risk of depression and anxiety disorders. Alcohol withdrawal can be life-threatening, causing seizures and delirium tremens.

Cannabis affects the brain differently. Long-term heavy use is associated with some cognitive impacts though many effects appear reversible with abstinence. Cannabis use has documented effects on adolescent brain development, particularly with heavy use. 

The most severe mental health risk of THC-heavy cannabis use is psychosis among those who are vulnerable to psychosis. It may also be true that people who are vulnerable to psychosis tend to seek out THC-heavy cannabis, but that doesn’t account for all of the risk. Finally, cannabis withdrawal symptoms are generally mild including irritability, sleep problem and anxiety. 

Addiction potential

Both cannabis and alcohol can be addictive, but the rates differ significantly. Approximately 10-15% of alcohol users develop alcohol use disorder. Alcohol dependence is associated with severe withdrawal symptoms and significant health, social and occupational consequences. 

Some 9% of cannabis users develop cannabis use disorder (rising to 17% for those who start in adolescence). Cannabis dependence also contributes to social and occupational challenges, but these are generally less severe than for alcohol dependence.

Social and Behavioral Impacts

This is where differences between alcohol and cannabis consumption become particularly stark. Alcohol is strongly associated with violence and aggression, being involved in about 40% of violent crimes, sexual assault (nearly half of sexual assaults involve alcohol), domestic violence and risky sexual behavior and decision-making

Cannabis users, on the other hand, typically show lower rates of violence and aggression, and reduced likelihood of risk-taking behavior.

The verdict 

Weighing the evidence across these seven categories, cannabis demonstrates a significantly safer profile than alcohol in six of seven areas, with driving impairment representing the one area of comparable concern. 

If you use THC-containing cannabis recreationally and don’t drive, it can be a far less harmful alternative to alcohol. But here’s the catch, many people co-use cannabis and alcohol. For drinkers considering switching to THC, this represents a sound harm reduction strategy. However, avoid the trap of adding cannabis while maintaining previous drinking levels — that compounds rather than reduces risk.

Both substances demand mindful, moderate use with full awareness of their distinct risk profiles. And regardless of which substance someone chooses, driving under the influence remains dangerous and unacceptable.

Understanding these differences helps us have more honest, evidence-based conversations about substance use policy and personal choices.