Neither marijuana nor nicotine is safe, but they damage the body in different ways and on different timelines. Nicotine, almost always delivered through tobacco, is responsible for roughly 120,000 excess deaths per year in Britain alone, spanning cancer, heart disease, and chronic lung disease. Marijuana’s long-term death toll is harder to quantify because widespread use is more recent and most cannabis smokers also use tobacco, making individual risks difficult to separate. The honest answer is that “worse” depends on what you’re measuring: addiction potential, lung damage, brain effects, or heart risk.
Addiction: Nicotine Hooks More Users
Nicotine is one of the most addictive substances in common use. Roughly 60 to 70% of people who smoke cigarettes regularly become dependent. Cannabis is less addictive on a per-user basis, but not by as wide a margin as many people assume. The CDC estimates that about 30% of people who use cannabis develop cannabis use disorder, meaning they struggle to stop despite negative consequences. That’s nearly one in three users.
The withdrawal experiences differ, too. Nicotine withdrawal hits fast, usually within hours, bringing irritability, intense cravings, and difficulty concentrating. Cannabis withdrawal is milder for most people but can include sleep disruption, mood swings, and reduced appetite lasting a week or two. Both substances are harder to quit the younger you start.
Lung Damage From Smoking
Burning any plant material and inhaling the smoke introduces tar, carbon monoxide, and carcinogens into your lungs. Tobacco smoking causes chronic bronchitis, emphysema, and is the leading preventable cause of lung cancer worldwide. Cannabis smoke produces many of the same inflammatory changes: chronic cough, chest infections, and damaged airways that look similar to what doctors see in cigarette smokers. One key difference is that these problems sometimes appear at younger ages in cannabis users, likely because joints are typically unfiltered and inhaled more deeply.
A case-control study published in the European Respiratory Journal found that each “joint-year” of cannabis smoking (one joint per day for one year) raised lung cancer risk by about 8%, while each pack-year of cigarettes raised it by about 7%. Heavy cannabis users in the highest category of use had a lung cancer risk nearly six times higher than non-users, even after adjusting for cigarette smoking. That finding challenges the common belief that marijuana doesn’t cause lung cancer. The caveat is that most cigarette smokers consume far more total smoke per day than most cannabis users, so population-level lung cancer rates remain much higher among tobacco smokers.
Heart and Stroke Risk
Tobacco’s connection to cardiovascular disease is well established: it damages blood vessel walls, raises blood pressure, and accelerates plaque buildup in arteries. Cannabis appears to carry its own cardiovascular risks, though the research is newer. A study highlighted by the National Heart, Lung, and Blood Institute found that people who smoked cannabis weekly had a 3% increased likelihood of heart attack and a 5% increased likelihood of stroke compared to non-users.
The mechanism isn’t fully understood. THC interacts with receptors found throughout the heart and blood vessels, which may contribute to the risk. Cannabis also raises heart rate acutely, sometimes by 20 to 50 beats per minute within minutes of use, which can be dangerous for people with existing heart conditions. Tobacco’s cardiovascular damage, though, compounds over decades and is the single largest contributor to heart disease deaths in most countries. On a population scale, nicotine delivered through cigarettes causes far more cardiovascular death.
Effects on the Developing Brain
This is one area where cannabis may carry greater risk than nicotine for young users. The brain continues developing into the mid-20s, and THC appears to disrupt that process in ways nicotine does not. Adolescents who use cannabis regularly show reduced performance on memory tasks, including both working memory (holding information in mind) and episodic memory (recalling past events). Brain imaging studies reveal that young cannabis users have smaller hippocampal volume on the right side, a region critical for learning and memory. They also show altered white matter integrity and changes in how the brain’s reward system responds, with heavier use linked to a blunted response to rewards over time.
Nicotine also affects the adolescent brain, particularly attention and impulse control circuits. But in some studies, nicotine actually showed a small positive effect on working memory tasks, a sharp contrast to cannabis. This doesn’t mean nicotine is good for developing brains. It still rewires reward pathways and increases vulnerability to addiction. The combined use of both substances, which is extremely common, appears to compound structural brain changes beyond what either causes alone.
Vaping Changes the Equation
Many users now vape rather than smoke, and the risk profiles shift depending on the delivery method. Nicotine e-cigarettes eliminate combustion but still expose lungs to harmful substances: heavy metals like nickel, tin, and lead, volatile organic compounds, ultrafine particles, and flavoring chemicals such as diacetyl, which is linked to serious lung disease. Nicotine itself remains highly addictive regardless of how it’s delivered, and it still harms adolescent brain development.
Cannabis vapes carry their own risks. The 2019 outbreak of severe lung injuries in the U.S. was traced largely to vitamin E acetate, an additive in illicit THC cartridges. Regulated cannabis vape products have since improved, but the long-term effects of inhaling vaporized cannabis concentrates, which deliver much higher THC doses than flower, remain unknown. Vaping either substance is likely less harmful than smoking it, but “less harmful” is not the same as safe.
How Frequency and Dose Matter
One reason this comparison is so difficult is that typical use patterns differ dramatically. A pack-a-day cigarette smoker inhales smoke 200 or more times daily, year after year, for decades. Most cannabis users consume far less frequently. That difference in cumulative exposure is a major reason tobacco kills more people overall. But for someone who smokes cannabis daily, especially starting in adolescence, the risks to the lungs, brain, and cardiovascular system are real and not trivial.
Potency matters, too. Today’s cannabis products often contain THC concentrations several times higher than what was common 30 years ago, and concentrates used in vaping can exceed 80% THC. Higher potency correlates with greater risk of cannabis use disorder and more pronounced cognitive effects. Meanwhile, cigarettes have been engineered for consistent nicotine delivery, keeping users locked into regular consumption patterns that sustain the addiction and its associated health costs.
The Bottom Line on “Worse”
Tobacco, as typically used, kills more people than cannabis by a wide margin. It is more addictive, causes more cancer, and drives more heart disease. But cannabis is not harmless, and in certain dimensions, particularly adolescent brain development and per-smoke cancer risk, it performs worse than many users expect. The safest comparison isn’t which substance is “less bad.” It’s recognizing that both carry meaningful health costs that scale with how much, how often, and how early in life you use them.