Tobacco increases marijuana risks

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Teenagers who see marijuana as a relatively low-risk drug may be more at risk for addiction than they realize, a new Yale paper says.

Co-occuring cannabis and tobacco use is significantly more likely to cause cannabis abuse and dependence than only cannabis use, according to a paper by Yale researchers accepted by the peer-reviewed journal Addiction last month. Psychiatry postdoctorate fellow Erica Peters said that she noticed consistent evidence across the literature of her conclusion and conducted the review to build momentum for the area of study. She said her study did not answer questions about the chemical pathways or the specifics of the drug interactions, but opened the door for future research.

“There’s something about tobacco use that seems to worsen marijuana use in some way,” Peters said.

She said that both simultaneous use — in the form of blunts, marijuana in a cigar wrapper — and use on separate occasions make cannabis more addictive. Co-occuring use also intensifies psychosocial problems, such as anxiety, depression and legal difficulties. The study found that adolescents were less likely to have good grades and more likely to have drunk alcohol in the past month.

Ninety percent of cannabis users also smoke tobacco, said Arpana Agrawal, an assistant professor of psychiatry at Washington University in St. Louis. By contrast, only 40 to 50 percent of tobacco users also smoke cannabis, she said.

“If you’re going to tackle one, you have to consider the other,” she said.

Agrawal said that for the first time, the Yale paper provides a “really comprehensive, systematic” understanding of cannabis dependence and abuse over the lifetime of an individual who smokes tobacco and cannabis.

The important next step is to understand the best approaches to clinical treatment for co-occuring users, Peters said. Clinicians have yet to develop a effective treatment for cannabis dependence, so understanding that tobacco affects the majority of cannabis users is important, Agrawal said.

Another of Agrawal’s papers examining nongenetic factors that motivate youth to use cannbis and marijuana was accepted by late month’s issue of Addiction. She hypothesized in the paper that the similar act of smoking may cause cannibis and tobacco use to reinforce each other.

The study reinforces the conclusions of existing literature on polysubstance use, RAND Drug Policy Research Center co-director Rosalie Pacula said in an email. Whether “cannabis and tobacco, alcohol and cocaine, alcohol and cigarettes, or cocaine and meth,” polysubstance use generally leads to more significant dependence and psychosocial problems, she said.

Yale Medical School psychiatry professor Kathleen Carroll and University of Arkansas psychiatry professor Alan Budney co-authored the paper.


  • malcolmkyle

    1) Tobacco is cancer causing largely because it delivers specific carcinogens such as NNK and NNAL that are not present in cannabis. Not all “tar” is created equal, and tobacco has some of the most carcinogenic types of tar known to science, whereas cannabis does not.

    2) Cannabis (marijuana) use is associated with a DECREASE in several types of cancer… potentially even providing a protective effect against tobacco and alcohol related cancer development.

    Donald Tashkin, a UCLA researcher whose work is funded by NIDA, did a case-control study comparing 1,200 patients with lung, head and neck cancers to a matched group with no cancer. Even the heaviest marijuana smokers had no increased risk of cancer, and had somewhat lower cancer risk than non-smokers (tobacco smokers had a 20-fold increased lung cancer risk). Tashkin D. Marijuana Use and Lung Cancer: Results of a Case-Control Study. American Thoracic Society International Conference. May 23, 2006.

    Researchers at the Kaiser-Permanente HMO, funded by NIDA, followed 65,000 patients for nearly a decade, comparing cancer rates among non-smokers, tobacco smokers, and marijuana smokers. Tobacco smokers had massively higher rates of lung cancer and other cancers. Marijuana smokers who didn’t also use tobacco had no increase in risk of tobacco-related cancers or of cancer risk overall. In fact their rates of lung and most other cancers were slightly lower than non-smokers. Sidney, S. et al. Marijuana Use and Cancer Incidence (California, United States). Cancer Causes and Control. Vol. 8. Sept. 1997, p. 722-728.

    In a 1994 study the government tried to suppress, federal researchers gave mice and rats massive doses of THC, looking for cancers or other signs of toxicity. The rodents given THC lived longer and had fewer cancers, “in a dose-dependent manner” (i.e. the more THC they got, the fewer tumors). NTP Technical Report On The Toxicology And Carcinogenesis Studies Of 1-Trans- Delta-9-Tetrahydrocannabinol, CAS No. 1972-08-3, In F344/N Rats And B6C3F Mice, Gavage Studies. See also, “Medical Marijuana: Unpublished Federal Study Found THC-Treated Rats Lived Longer, Had Less Cancer,” AIDS Treatment News no. 263, Jan. 17, 1997.

    Cannabinoids Curb Brain Tumor Growth, First-Ever Patient Trial Shows

    Pot Compound May Offer Non-Toxic Alternative To Chemotherapy

    Tetrahydrocannabinol inhibits lung cancer as well as metastasis

    Inhibition of skin tumor growth by activation of cannabinoid receptors

    So there we have it: Tobacco Causes Cancer and Cannabis Prevents Cancer – even when smoked!

  • Goldie08

    anecdotally, I definitely noticed my marijuana use increase as I started to smoke more and more cigarettes. Now that i’ve quit tobacco, I smoke much less pot (not cause I don’t want to – I love weed. Just smoke much less frequently and much smaller quantities). I imagine it had something to do with linking the less physically dependent MJ with the very physically dependent tobacco. Every time I smoked a cigarette, I felt like a bowl afterwards.

    Also, I’ve been using a volcano vape for the last 3 years, and (again, anecdotally) believe that filters out a lot of the plant matter in pot that I think causes some of the physical dependence. I still smoke blunts, but that’s because I find passing a dutch with friends one of the purest and most fun ways to blaze. I’ve found the cigar not counter productive to my efforts to stay off cigarettes. Even have some pipe tobacco now and then (owl show pipe purchased freshman year) or hookah, and have not had problems getting back on cigarettes.

    Quitting cigarettes sucked, but after passing through the initial physical withdrawl symptoms (with the help of a few pieces of nicorette a day), its all a question of willpower.

  • jamesdakrn

    Use a bong or get a vape. Europeans are sooo weird when they mix in shitty tobacco w/ weed lol

  • snuffy

    naw, that’s dumb as hell. weeds good for you. an eighth a day keeps the sugar and stress low. and a cigarette after is the cherry on top. lordy lord it feels good

    smoke weed eeerDAY

  • anon12

    “By contrast, only 40 to 50 percent of tobacco users also smoke cannabis”.

    There is no way that this fact is true. A brief internet search will show you that around 20% of people in the US smoke, and while a fair number of adults have smoked week in the last year (around 1/12), the number of chronic marijuana users is definitely below 5% of the population.