We took a scientific look at whether weed or alcohol is worse for you — and there appears to be a winner

Shutterstock Marijuana and alcohol have long been portrayed as relatively similar vices with a variety of risks and a few benefits.

Based on the available peer-reviewed scientific research, however, one appears to pose more health risks overall.

That said, there are dozens of health factors to consider when comparing the substances - from one's family medical history to the legality of each drug. Which is worse for you: weed or whiskey? It's a tough call, but based on the peer-reviewed science, there appears to be a clear answer. Keep in mind that there are dozens of factors to account for when comparing the health effects of alcohol and marijuana, including how the substances affect your heart, brain, and behavior, and how likely you are to get hooked. Time is important, too - while some effects are noticeable immediately, others only begin to crop up after months or years of use. Never miss out on healthcare news. Subscribe to Dispensed, our weekly newsletter on pharma, biotech, and healthcare. The comparison is slightly unfair for another reason: While scientists have been researching the effects of alcohol for decades, the science of cannabis is murkier because of its mostly illegal status. Here's what we know about which substance is more harmful.

A large new study suggested that for people between the ages of 15 and 49 years old worldwide, alcohol was the leading risk factor for death in 2016. Smile19/Shutterstock A large review published in August in the medical journal The Lancet found that among people aged 15-49, alcohol use was the leading health risk factor across the globe in 2016, with 3.8% of all female deaths and 12·2% of all male deaths attributable to alcohol use. The review looked at published data from nearly 600 studies that comprised data on 195 countries and territories between 1990 and 2016. The results showed that among people of all ages, alcohol was the seventh leading risk factor for deaths in 2016. The more people drank across the globe, the more their risk of dying and their risk of cancer rose, the study authors found. As a result of these findings, they concluded that there was no "safe" level of alcohol consumption. "Alcohol use is a leading risk factor for global disease burden and causes substantial health loss," the researchers wrote in their paper, "and the level of consumption that minimizes health loss is zero."

More than 30,700 Americans died from alcohol-induced causes in 2014. There have been zero documented deaths from marijuana use alone. Gerardo Garcia/Reuters In 2014, 30,722 people died from alcohol-induced causes in the US - and that does not count drinking-related accidents or homicides. If those deaths were included, the number would be closer to 90,000, according to the Centers for Disease Control and Prevention. Meanwhile, no deaths from marijuana overdoses have been reported, according to the Drug Enforcement Administration. A 16-year study of more than 65,000 Americans, published in the American Journal of Public Health, found that healthy marijuana users were not more likely to die earlier than healthy people who did not use cannabis.

Marijuana appears to be significantly less addictive than alcohol. Shutterstock Close to half of all adults have tried marijuana at least once, making it one of the most widely used illegal drugs - yet research suggests that a relatively small percentage of people become addicted. For a 1994 survey, epidemiologists at the National Institute on Drug Abuse asked more than 8,000 people from ages 15 to 64 about their drug use. Of those who had tried marijuana at least once, roughly 9% eventually fit a diagnosis of addiction. For alcohol, the figure was about 15%. To put that in perspective, the addiction rate for cocaine was 17%, while heroin was 23% and nicotine was 32%.

Marijuana may be harder on your heart, while moderate drinking could be beneficial. Flickr/maxbraun Unlike alcohol, which slows your heart rate, marijuana speeds it up, which could negatively affect the heart in the short term. Still, the largest-ever report on cannabis from the National Academies of Sciences, released in January, found insufficient evidence to support or refute the idea that cannabis may increase the overall risk of a heart attack. On the other hand, low to moderate drinking - about one drink a day - has been linked with a lower risk of heart attack and stroke compared with abstention. James Nicholls, a director at Alcohol Research UK, told The Guardian that those findings should be taken with a grain of salt since "any protective effects tend to be canceled out by even occasional bouts of heavier drinking."

Both drugs may be linked with risks while driving, but alcohol is worse. Unsplash / Michael Discenza A research note published by the National Highway Traffic Safety Administration (PDF) found that, when adjusting for other factors, having a detectable amount of THC (the main psychoactive ingredient in cannabis) in your blood did not increase the risk of being involved in a car crash. Having a blood-alcohol level of at least 0.05%, on the other hand, increased that risk by 575%. Still, combining the two appears to have the worst results. "The risk from driving under the influence of both alcohol and cannabis is greater than the risk of driving under the influence of either alone," the authors of a 2009 review wrote in the American Journal of Addiction.

Several studies link alcohol with violence, particularly at home. That has not been found for cannabis. Matilde Campodonico/AP It's impossible to say whether drinking alcohol or using marijuana causes violence, but several studies - including a recent analysis published in the journal Cognitive, Affective, and Behavioral Neuroscience - suggest a link between alcohol and violent behavior. For the study, which was published in January, researchers used fMRI scans to see how two alcoholic drinks impacts brain function in 50 healthy adult males. Compared with sober participants, the intoxicated volunteers were found to have reduced functioning in the prefrontal cortex, an area of the brain linked with moderating social behavior. That reduced functioning was also linked with aggressive behavior. The finding aligns with some previous research on alcohol's connections with violence. According to the National Council on Alcoholism and Drug Dependence, alcohol is a factor in 40% of all violent crimes, and a study of college students found that the rates of mental and physical abuse were higher on days when couples drank. On the other hand, no such relationship appears to exist for cannabis. A recent study looking at cannabis use and intimate partner violence in the first decade of marriage found that marijuana users were significantly less likely to commit violence against a partner than those who did not use the drug.

Both drugs are linked with an increased risk of psychiatric disease. For weed users, psychosis and schizophrenia are the main concern; with booze, it's depression and anxiety. iStock The largest review of marijuana studies found substantial evidence of an increased risk among frequent marijuana users of developing schizophrenia - something that studies have shown is a particular concern for people already at risk. Weed can also trigger temporary feelings of paranoia and hostility, but it's not yet clear whether those symptoms are linked with an increased risk of long-term psychosis. On the other hand, self-harm and suicide are much more common among people who binge drink or drink frequently. But scientists have had a hard time deciphering whether excessive alcohol use causes depression and anxiety or whether people with depression and anxiety drink in an attempt to relieve those symptoms.

Alcohol appears to be linked more closely with weight gain, despite weed's tendency to trigger the munchies. Melia Robinson/Business Insider Weed gives you the munchies. It makes you hungry, reduces the natural signals of fullness, and may even temporarily make food taste better. But despite eating over 600 extra calories when smoking, marijuana users generally don't have higher body-mass indexes. In fact, studies suggest that regular smokers have a slightly reduced risk of obesity. Alcohol, on the other hand, appears to be linked with weight gain. A study published in the American Journal of Preventative Medicine found that people who drank heavily had a higher risk of becoming overweight or obese. Plus, alcohol itself is caloric: A can of beer has roughly 150 calories, and a glass of wine has about 120.