“Cannabis is legal here, so it is harmless. I only smoke cigarettes with it.” I have heard this sentence often from young Iranians in Vancouver and Toronto. Afterward, the same client usually describes bad sleep, heavy mornings, and anxiety that they say they “do not know where it comes from.” Data from 53,000 people say where it comes from.
Why Is Using Cannabis and Tobacco Together Worse Than Either Alone?
The short answer: anxiety and depression in people who use cigarettes and cannabis together are nearly double the rates in people who use neither, and higher than in people who smoke only one. This figure comes from a large digital cohort, not a small clinical sample.
Nguyen and colleagues at the University of California, San Francisco analyzed data from 53,843 American adults between 2020 and 2022. Of these, 4.9 percent used only tobacco, 6.9 percent used only cannabis, 1.6 percent used both, and 86.6 percent used neither. In the co-use group, 26.5 percent of people reported anxiety and 28.3 percent of people reported depression; in the nonuse group, 10.6 percent of people reported anxiety and 11.2 percent of people reported depression. That means for every 100 people in the co-use group, about 28 people had depression, compared with 11 people who had depression in the nonuse group. [1]
After statistical adjustment, the odds of anxiety in the co-use group were 1.89 times the odds of anxiety in the nonuse group, and the odds of depression in the co-use group were 1.77 times the odds of depression in the nonuse group. Compared with tobacco use only, the odds of anxiety with co-use were 1.35 times higher, but the difference for depression was not statistically significant. This detail matters: adding cannabis to cigarettes is linked more strongly to anxiety than to depression.
What calms the night weighs down the morning: the cycle of using to relax
“I Smoke to Relax”—Why Does the Cycle Turn Against Itself?
Because the data show correlation, not causation, and this ambiguity is exactly where the cycle forms. A person with anxiety smokes to calm down; the short-term effect is real; but the same study showed that daily cigarette smoking, daily e-cigarette use, and daily cannabis use, each separately, were associated with higher odds of anxiety and depression. [1] Daily use went with lower mood.
In Civilization and Its Discontents (1930; Standard Edition, Vol. 21), Freud describes intoxication as the crudest yet most effective method people have for keeping suffering at bay. That insight explains the cycle seen in nightly cigarette and cannabis use: discomfort is switched off at once, but the underlying pain never reaches words and returns the next night. [4]
The study’s limitation should be stated plainly: the sample was a convenience sample rather than a random sample, the mean age was 51 years, 68 percent were women, and all measures were self-reported. These data cannot say that cannabis causes depression; they can say that people who use both substances have systematically worse mood, and greater use is associated with worse mood. [Needs further review: the share of self-medication versus the direct effect of the substances cannot be separated in this cohort.]
In summary: for some people these substances are a painkiller, but a painkiller that is needed every night does not treat the pain; it hides it.
Who Faces the More Serious Risk?
For people with a family history or early signs of psychosis, the combination of cannabis and tobacco goes beyond bad mood. Bello and colleagues in 2026 published data from the NAPLS-2 study: 1,012 people, including 734 individuals at clinical high risk for psychosis and 278 healthy controls. [2]
In this group, greater cannabis use and greater tobacco use were associated with more severe psychiatric symptoms. More importantly, heavy cannabis use with light tobacco use was associated with a 2.93-fold higher risk of transition to full psychosis (hazard ratio 2.93; 95% confidence interval 1.23 to 6.97). The subtle point: co-use was not related to current symptom severity, but predicted the future. That is, someone who today feels fine can be on a risk path without realizing it.
The limitation of this study is also clear: it examined only people at high risk and does not generalize to the general population. But for families with a history of psychiatric disorder, this finding is a specific warning, not a remote possibility.
Why Is the First Week of Quitting Harder for This Group?
Because a body habituated to two substances experiences more severe withdrawal in the first week. Rabin and colleagues (2025) in a multicenter tobacco cessation trial compared 330 people who had quit by the end of treatment: 55 were cannabis co-users and 275 were tobacco-only users. In the first week, the severity of withdrawal symptoms in the co-use group was 9.3, compared with 7.1 in the tobacco-only group; from week 4 onward there was no difference. [3]
This means two things. First, about 30 percent of tobacco users also use cannabis, and in my experience most of them do not know that quitting will be harder for them in the first week. Second, this difficulty is temporary. If someone gets through the first week with support, the rest of the path is no different from anyone else’s. The pattern I have seen in the therapy room is this: setbacks almost always happen in those first seven days, and a person who knows in advance that this week is hard usually gets through it.
Legality says nothing about psychological safety. In the 53,000-person cohort, cannabis use alone was associated with higher odds of anxiety and depression, and co-use with cigarettes brought those odds to nearly double the nonuse group.
What if I only smoke on weekends?
The data show daily use is the worst pattern and less frequent use carries lower risk. But for many people, weekend use gradually becomes every-night use, especially when it serves to silence anxiety. The criterion is not frequency; it is function.
Why do I feel calm when I smoke but worse in the morning?
The short-term effect is real; the long-term effect is also real and runs in the opposite direction. Nguyen’s study showed that daily use of each of these substances is associated with lower mood. The night’s relaxation is a loan you repay with interest in the morning.
We have a family history of psychiatric disorder; what should we do?
In people at high risk, heavy cannabis use with tobacco was associated with nearly 3 times the risk of transition to psychosis. For this group, reducing or stopping use is not a lifestyle choice; it is a specific preventive action best planned with a professional.
What Does This Mean in Practice?
A young person who enters the room saying “cannabis is legal” usually leaves with another question: “What am I silencing with it?” Once that question is answered, the substance tends to lose its function. The hardest part is seven days—and seven days can be crossed.
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Nguyen N, Peyser ND, Olgin JE, et al. Associations between tobacco and cannabis use and anxiety and depression among adults in the United States: Findings from the COVID-19 citizen science study. PLoS One. 2023;18(9):e0289058. PMID: 37703257. DOI: 10.1371/journal.pone.0289058
Bello D, Blyth SH, Rabin RA, et al. Cannabis and tobacco co-use predicts psychosis in clinical high risk cohorts. Nat Ment Health. 2026;4(6):941-950. PMID: 42291778. DOI: 10.1038/s44220-026-00648-y
Rabin RA, Lerman C, Schnoll R, Tyndale RF, George TP. A multi-site study examining the tobacco withdrawal trajectory in people with tobacco and cannabis co-use. Drug Alcohol Depend. 2025;274:112778. PMID: 40633181. DOI: 10.1016/j.drugalcdep.2025.112778
Freud S. Civilization and Its Discontents (1930). In: The Standard Edition of the Complete Psychological Works of Sigmund Freud, Vol. 21. London: Hogarth Press; 1961. (theoretical source)
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