Misinformation has run rampant over the use of marijuana for decades. In 1936, the church group-financed movie Reefer Madness taught the public about the perils presented in using the drug — everything from attempted murder to suicide and madness. Around the same time, Harry Anslinger and others began the war on drugs, which was at least partly fueled by racist motives. Ever since, rumors and or slanted science about weed has often filled in a gaping hole in research due to restrictions on drugs illegalized by western governments. That said, the legalization of marijuana in various states and countries has led to marketing campaigns making sometimes dubious claims of the herb’s health benefits.

Some people have long tended to lump all illegal drugs together, seeing little difference between the dangers posed by drugs like heroine or methamphetamines to marijuana. But how dangerous is marijuana, really? Can it kill you? Is it possible to overdose on weed?

The answer to the latter question is an easy “no.” There are some ways that joints, bong hits or synthetic versions of the psychoactive agents in marijuana can kill you, but overdosing on pure, unadulterated marijuana that isn’t mixed with anything is very nearly impossible.

“It’s not close to alcohol or opiate toxicity,” says Mujeeb Shad, a psychiatrist with the University of Nevada, Las Vegas.

Why the Danger of Marijuana Is Self-Mitigated

The reason marijuana doesn’t pose the same sort of risk as opiates, cocaine, amphetamines or even alcohol is that some of the active components of the pungent herb work against each other in your body.

Tetrahydrocannabinol, or THC, is probably the most toxic component of marijuana. It’s also what’s responsible for most of the more potent psychoactive and addictive effects that users.

Over the past few decades, the THC content of marijuana has increased, meaning that, in theory, the addictive potential for the drug has increased. THC is considered a partial agonist, which means it isn’t actually very toxic, especially compared with more dangerous drugs like opiates or cocaine that can be toxic or lethal at high doses. But even if the THC content was high enough to cause real damage to your body, marijuana also has a built-in way to keep this component in check: cannabidiol, or CBD.

You may be familiar with CBD due to the plethora of New Age health practitioners that sell the substance in everything from balms to edible products, though the science hasn’t yet caught up to some of these claims.

But CBD dampens some of the potentially adverse effects of THC, counteracting some of its toxicity.

“[CBD] is kind of a system stabilizer,” Shad says.

Marijuana can certainly cause negative effects, whether that means nausea, paranoia, vomiting, delusions, confusion or anxiety. But it’s unlikely to kill you by itself.

Synthetic Marijuana and Drug Cocktails

While the natural form of marijuana may not be toxic enough to cause overdose, Shad says newer synthetic forms of THC currently available on the illegal market like Spice or K2 are a different story. These drugs have substantial effects and can be highly toxic, as they don’t carry any of the balancing elements the herb has. 

“They can be extremely toxic, people can die from them,” Shad says, adding that many of these synthetic THC drugs are full agonists rather than partial agonists like more organic forms of THC. In fact, he and his co-authors even proposed using CBD as a potential treatment for toxicity caused by Spice or K2.

Another problem comes when marijuana is laced with other substances, whether it’s other psychedelics, opiates, or designer drugs. “That can lower the relative safety of marijuana,” Shad says.

Other drugs can also counteract the balance between THC and CBD, allowing the toxic elements normally curtailed in marijuana to do more harm. As a result, combining marijuana with drugs like opiates or cocaine could create a toxic mixture that is greater than the sum of its parts, Shad says.

Long-Term Issues

The decades-long freeze on research means that solid science on the impacts of longer-term marijuana use is lacking. But just the same, smoking marijuana rather than eating it can cause many of the same problems that smoking tobacco can. The inhalation of hydrocarbons from the burning material can lead to lung cancer or heart problems. Many people mix marijuana with tobacco in joints, or smoke the substance without filters, which also increases the negative impacts.

“That’s why smoking marijuana is much more problematic than using it in other ways,” Shad says.

Shad adds that marijuana use by children under 15 has also been linked to an increased chance of schizophrenia later in life. In general, people with schizophrenia could see their conditions worsened by marijuana use.

One effect that may compare with alcohol is driving, however. Similar to drinking and driving, marijuana can slow your motor functions, which can increase the time it takes your brain and body to react. “The slower reflexes can cause problems,” Shad says.

In other words, smoking joints and driving is not a good idea, just the same way as taking bong hits before revving up the chainsaw is probably not in your best interests.

But the dangers of marijuana use in and of itself are often far overblown, especially when considering that another legal drug — alcohol — is far deadlier. You can probably kill yourself with less than $100 of hard alcohol if you drink it quickly enough.