Based on scientific knowledge, there is a clear answer to this question.
Keep in mind that there are dozens of factors to consider, including how the substance affects the heart, brain, and behavior, as well as how easy it is to get used to.
Time is also of the essence: some effects are noticeable immediately, while others accumulate over months or years of use.
And yes, it's a bit unfair to compare because the effects of alcohol have been studied by scientists for decades, but there's still a lot of misunderstanding with cannabis because it has a largely illegal status.
Keep in mind that there are dozens of factors to consider, including how the substance affects the heart, brain, and behavior, as well as how easy it is to get used to.
Time is also of the essence: some effects are noticeable immediately, while others accumulate over months or years of use.
And yes, it's a bit unfair to compare because the effects of alcohol have been studied by scientists for decades, but there's still a lot of misunderstanding with cannabis because it has a largely illegal status.
In 2014, more than 30,000 Americans died from alcohol-induced causes. No deaths from marijuana use were recorded.
In 2014, 30,722 people died of alcohol-related causes in the U.S. - and that's not counting alcohol-related disasters and homicides. If you count that too, the figure is close to 90,000.
According to the U.S. Drug Enforcement Administration, there have been no deaths from marijuana overdoses. According to a 16-year study involving more than 65,000 Americans published in the American Journal of Public Health, healthy cannabis users do not die before healthy people who do not smoke marijuana.
Marijuana is significantly less addictive than alcohol.
Nearly half of adults have tried marijuana at least once. It is one of the most commonly used illicit drugs. And yet, studies show that a relatively small percentage of people become addicted.
In 1994, epidemiologists at the National Institute on Drug Abuse surveyed more than 8,000 people between the ages of 15 and 64. Of those who had tried marijuana at least once, only about 9% fell under the diagnosis of addiction. Among those who had used alcohol, the proportion was about 15%. Among those who had tried cocaine 17%, heroin 23% and nicotine 32%.
In 2014, 30,722 people died of alcohol-related causes in the U.S. - and that's not counting alcohol-related disasters and homicides. If you count that too, the figure is close to 90,000.
According to the U.S. Drug Enforcement Administration, there have been no deaths from marijuana overdoses. According to a 16-year study involving more than 65,000 Americans published in the American Journal of Public Health, healthy cannabis users do not die before healthy people who do not smoke marijuana.
Marijuana is significantly less addictive than alcohol.
Nearly half of adults have tried marijuana at least once. It is one of the most commonly used illicit drugs. And yet, studies show that a relatively small percentage of people become addicted.
In 1994, epidemiologists at the National Institute on Drug Abuse surveyed more than 8,000 people between the ages of 15 and 64. Of those who had tried marijuana at least once, only about 9% fell under the diagnosis of addiction. Among those who had used alcohol, the proportion was about 15%. Among those who had tried cocaine 17%, heroin 23% and nicotine 32%.
Marijuana is more harmful to the heart, whereas moderate alcohol consumption can be beneficial.
Unlike alcohol, which slows the heart rate, cannabis speeds it up, which can have an overall negative effect on the heart. However, a report on marijuana published in January by the U.S. National Academy of Sciences said there is insufficient evidence to support or refute the claim that cannabis can increase the risk of heart attack.
On the other hand, moderate alcohol consumption - on the order of one drink a day - has been linked to a reduced risk of heart attack and stroke. James Nichols, director of Alcohol Research UK, told the Guardian that these findings should be viewed with a degree of skepticism because «all the protective effects are neutralized by episodes of heavy drinking».
Alcohol use has been linked to the development of several cancers, smoking cannabis has not.
In November, a group of influential American oncologists released a statement urging people to drink less. They cited strong evidence that drinking alcohol - even a glass of wine or beer a day - increases the risk of developing breast cancer.
The U.S. Department of Health lists alcohol as a known carcinogen. According to a study conducted by the National Institute for Cancer Research, the more alcohol you drink, especially on a regular basis, the higher your risk of getting cancer.
As for marijuana, some studies have linked smoking and lung cancer, but those results have been disproven. A January report suggests that cannabis is not linked to an increased risk of getting lung cancer or head and neck cancer.
Both substances pose a risk when driving, but alcohol is more dangerous.
According to a study published by the U.S. National Highway Traffic Safety Administration, having a detectable amount of THC (the main psychoactive ingredient in cannabis) in your blood does not increase your risk of being involved in a car accident. Meanwhile, a blood alcohol level of at least 0.05% increases that risk by 575%.
However, the combination of the two substances shows worse results. "The risk for driving under the influence of alcohol and marijuana is higher than the risk for driving under the influence of either substance alone", wrote the authors of a 2009 paper published in the American Journal of Addiction.
Studies link alcohol use to violence, particularly domestic violence. No such data are available for smoking cannabis.
A number of studies suggest a link between alcohol and violent behavior. According to the U.S. National Council on Alcoholism and Drug Dependence, alcohol is implicated in 40% of violent crimes, and a study of college student behavior demonstrates that rates of psychological and physical violence are higher on days when couples drink alcohol.
In the case of marijuana, no such correlation appears to exist. According to a recent study of the relationship between cannabis use and partner violence in the first ten years of marriage, users of the drug are significantly less likely to engage in partner violence than those who do not smoke it.
According to a study published by the U.S. National Highway Traffic Safety Administration, having a detectable amount of THC (the main psychoactive ingredient in cannabis) in your blood does not increase your risk of being involved in a car accident. Meanwhile, a blood alcohol level of at least 0.05% increases that risk by 575%.
However, the combination of the two substances shows worse results. "The risk for driving under the influence of alcohol and marijuana is higher than the risk for driving under the influence of either substance alone", wrote the authors of a 2009 paper published in the American Journal of Addiction.
Studies link alcohol use to violence, particularly domestic violence. No such data are available for smoking cannabis.
A number of studies suggest a link between alcohol and violent behavior. According to the U.S. National Council on Alcoholism and Drug Dependence, alcohol is implicated in 40% of violent crimes, and a study of college student behavior demonstrates that rates of psychological and physical violence are higher on days when couples drink alcohol.
In the case of marijuana, no such correlation appears to exist. According to a recent study of the relationship between cannabis use and partner violence in the first ten years of marriage, users of the drug are significantly less likely to engage in partner violence than those who do not smoke it.
Both substances negatively affect memory, but in different ways. This effect is particularly prevalent in heavy, frequent or heavy drinkers.
Both weed and alcohol temporarily impair memory, and alcohol can cause memory lapses by impairing the brain's ability to form memories. The most serious effects are seen in those who drink heavily, frequently, or binge drink and began doing so in their teens.
Studies say these effects can persist for weeks after stopping smoking cannabis. Researchers also say there is a link between daily marijuana use and poor verbal memory in adults who started smoking at a young age.
Chronic alcoholics have impaired memory, attention and planning, as well as impaired emotional processes and social cognition - and this can all persist after years of abstinence.
Both substances are associated with an increased risk of developing mental illness. In the case of cannabis users, this is most often psychosis and schizophrenia; in the case of alcohol users, it is most often depression and anxiety disorder.
An analysis of multiple studies of marijuana shows substantial evidence of an increased risk of schizophrenia among those who use the substance regularly, especially those who are already at risk.
Weed can also cause temporary paranoia and hostility, but it is not yet clear whether these symptoms are associated with an increased risk of long-term psychosis.
On the other hand, self-harm and suicide are much more common among those who drink frequently or binge drink. However, scientists cannot yet understand whether it is excessive drinking that causes depression and anxiety or whether people with depression and anxiety drink in an attempt to relieve these symptoms.
Both weed and alcohol temporarily impair memory, and alcohol can cause memory lapses by impairing the brain's ability to form memories. The most serious effects are seen in those who drink heavily, frequently, or binge drink and began doing so in their teens.
Studies say these effects can persist for weeks after stopping smoking cannabis. Researchers also say there is a link between daily marijuana use and poor verbal memory in adults who started smoking at a young age.
Chronic alcoholics have impaired memory, attention and planning, as well as impaired emotional processes and social cognition - and this can all persist after years of abstinence.
Both substances are associated with an increased risk of developing mental illness. In the case of cannabis users, this is most often psychosis and schizophrenia; in the case of alcohol users, it is most often depression and anxiety disorder.
An analysis of multiple studies of marijuana shows substantial evidence of an increased risk of schizophrenia among those who use the substance regularly, especially those who are already at risk.
Weed can also cause temporary paranoia and hostility, but it is not yet clear whether these symptoms are associated with an increased risk of long-term psychosis.
On the other hand, self-harm and suicide are much more common among those who drink frequently or binge drink. However, scientists cannot yet understand whether it is excessive drinking that causes depression and anxiety or whether people with depression and anxiety drink in an attempt to relieve these symptoms.
Alcohol is more associated with weight gain, regardless of marijuana's property of inducing the desire to eat.
After smoking weed, the pig attacks. It makes you hungry, weakens natural satiety signals, and may even temporarily improve the taste of food.
However, despite the fact that when smoked, cannabis users eat 600 calories more than usual, on average they don't have an increased BMI. Studies even suggest that those who smoke regularly have a slightly reduced risk of developing obesity.
Alcohol, on the other hand, appears to be linked to weight gain. According to a study published in the American Journal of Preventative Medicine, people who drink a lot have an increased risk of obesity. Plus, alcohol itself is caloric: a small can of beer contains about 150 calories, while a glass of wine contains about 120.
Overall, the health effects of alcohol are far more dangerous than those of cannabis.
In terms of the potential for addiction or overdose - combined with the risk of cancer, traffic accidents, violence and obesity - science considers cannabis to be less harmful to health than alcohol.
Still, because marijuana is illegal in most places, the number of long-term studies of its health effects is limited, and scientists still have work to do.
After smoking weed, the pig attacks. It makes you hungry, weakens natural satiety signals, and may even temporarily improve the taste of food.
However, despite the fact that when smoked, cannabis users eat 600 calories more than usual, on average they don't have an increased BMI. Studies even suggest that those who smoke regularly have a slightly reduced risk of developing obesity.
Alcohol, on the other hand, appears to be linked to weight gain. According to a study published in the American Journal of Preventative Medicine, people who drink a lot have an increased risk of obesity. Plus, alcohol itself is caloric: a small can of beer contains about 150 calories, while a glass of wine contains about 120.
Overall, the health effects of alcohol are far more dangerous than those of cannabis.
In terms of the potential for addiction or overdose - combined with the risk of cancer, traffic accidents, violence and obesity - science considers cannabis to be less harmful to health than alcohol.
Still, because marijuana is illegal in most places, the number of long-term studies of its health effects is limited, and scientists still have work to do.