In a gender‐balanced sample of young adults co‐using tobacco and cannabis in France, we observed overall, comparable proportions of preference for the three dual cessation strategies: simultaneous cessation, quitting tobacco first and quitting cannabis first. However, preference for simultaneous cessation appeared to be more frequently reported among people with a less frequent or non‐dependent pattern of co‐use. Electronic cigarette, CBD and sport (plus nicotine replacement therapy for tobacco) were the most cited types of methods previously used and likely to be used for future quit attempts for both substances.

Simultaneous cessation, while generally considered acceptable in previous studies [34], is therefore not an obvious choice when young adults who co‐use have to consider quitting both substances. After multiple adjustments, we found that preference for simultaneous cessation was less probable than other choices in people with frequent use of both substances or, alternatively, in people with tobacco or cannabis dependence according to validated scales. It was also, to some extent, a more probable choice in people who perceived themselves, or were identified, as non‐dependent on either substance. Therefore, simultaneous cessation seems to be preferred by people engaged in lower‐frequency or non‐dependent co‐use, but not for people most at risk of co‐use‐related harms. Those results also imply that simultaneous cessation is preferred by people who may face less difficulty in quitting tobacco and cannabis. Indeed, it has been observed that for both substances, the higher the consumption level, the poorer the cessation outcomes [70, 71, 72, 73].

People who felt more dependent on one substance tended to prefer to quit the other first—a strategy of “starting with the easier one.” Although continuing one substance can trigger relapse to the other, quitting one may also increase the likelihood of successfully stopping the second [74, 75], supporting this “easier first” strategy.

First, tobacco cessation outcomes are poorer among people who co‐use cannabis [26, 27, 28, 29], meaning that successful cannabis cessation first may increase the likelihood of quitting tobacco in a second time, despite a transient increase in tobacco smoking after cannabis cessation [76]. Regarding tobacco cessation first, a 2017 review concluded that tobacco smoking cessation does not appear to have a negative effect and often has a positive effect on substance use outcomes [77]. Specifically, two studies previously found that tobacco cessation had positive effects on cannabis use frequency in people with heavy alcohol use [78], and on cannabis relapse in adolescents seeking treatment for substance use [79]. While poorly documented, we may lastly expect that a first success in substance cessation may increase self‐esteem, self‐worth, self‐confidence, or self‐efficacy, that will in turn improve the chances of a second successful cessation [80, 81].

We observed a tendency for participants to prefer quitting first the substance perceived as more harmful. Health concerns are common motives for quitting tobacco and cannabis [82, 83], and tobacco is generally perceived as more harmful than cannabis by young people [84, 85]. Our findings suggest that, for individuals not ready for simultaneous cessation, providing clear and complementary information on health risks may support a sequential approach starting with the substance perceived as more harmful.

Our results therefore pointed out the fact that sequential cessation may be preferred and more suited to some groups of people who co‐use. Respecting patients' preferences generally improves substance use treatment outcomes [86, 87]. Therefore, there is a need to explore how sequential cessation could be feasible, and how it may be prepared, accompanied and improved. For instance, mulling (i.e., mixing tobacco with cannabis within joints), which is common in Europe and France [19, 88], may be a barrier to tobacco cessation first. Decoupling cannabis use from its mixture with tobacco may therefore be necessary prior to implementing such a sequential cessation. One way to do so may be to switch from joints to vaporizers for cannabis administration [89, 90]. While expensive and probably not adapted for some people who co‐use, such a cessation method seems acceptable by some, according to our results on methods likely to be used. Moreover, progressive replacement of tetrahydrocannabinol (THC)‐rich cannabis with tetrahydrocannabinol‐low cannabis (generally rich in CBD) within joints to reach tobacco‐containing but THC‐low or THC‐free joints deserves further investigation [53, 91], as CBD appeared highly acceptable in our study sample.

The interrelatedness of tobacco and cannabis use has been reported related to patterns of use [92]. Future studies are needed to further explore how temporal and contextual proximity between tobacco and cannabis use influences preferences for sequential versus simultaneous quitting, as well as the success of these cessation strategies. In our sample, few participants reported smoking “pure” cannabis (i.e., in tobacco‐free joints). Consequently, our analyses yielded wide confidence intervals and the preference for quitting tobacco first—compared to simultaneous cessation—was not significantly associated with “not always mixing,” despite a relatively high adjusted odds ratio. Regarding same‐occasion use patterns, our descriptive analyses suggest that participants who preferred quitting cannabis first were more likely to commonly use tobacco without using cannabis during a single occasion. Inversely, those who preferred to quit tobacco first were more likely to commonly use cannabis without using tobacco during a single occasion (though this pattern was infrequent). These findings suggest that complementary use (i.e., when one substance enhances or completes the effects of the other) may act as a barrier to sequential cessation. In contrast, independent use of each substance may facilitate the success of sequential quitting strategies. One of the mechanisms that could explain these patterns is the triggering of both substances' use by shared conditioned cues, acquired through their concurrent use, as well as the triggering of one substance's use by the use of the other [93]. Taken together, these findings highlight the need for more precise data collection on patterns of co‐use in future research, particularly regarding same‐occasion use and co‐administration of tobacco and cannabis.

While it is acknowledged that both substances should be taken into account in case of co‐use treatment [94], to date, there are no clinical practice guidelines for treating tobacco‐cannabis co‐use [34]. Regarding tobacco cessation in young people, a 2017 Cochrane review concluded that evidence remains limited for all intervention types, whether they are behavioural or pharmacological [95]. For CUD treatment generally, evidence is also limited regarding the effectiveness of psychological and pharmacological interventions [96, 97]. For tobacco cessation, the French National Authority for Health recommended in 2023 care by a healthcare professional to ensure follow‐up, as well as the initiation of pharmacological treatment if necessary (nicotine replacement therapy being the first‐line treatment). Vaping products “could be used for specific smokers and/or vulnerable populations” (such as people with co‐addictions), but “only in the event of failure or poor adherence to treatment, and when the target populations explicitly express a preference for vaping devices”, and with tobacco cessation as a target [49]. There is no approved treatment, nor official published treatment guidelines for CUD in France.

In our sample, 34.5% of participants used electronic cigarette (10.9% for daily use, a figure close to the one observed in adults who co‐use tobacco and cannabis in France in 2021 (8.4%) [16]). Among these users, almost two‐thirds reported using it to reduce or quit tobacco. This is consistent with what was reported among dual U.S. adults who use cigarettes and electronic cigarettes [98]. Accordingly, in our sample, most participants who used electronic cigarette had previously attempted to quit tobacco using it, and most also intended to use it in future tobacco cessation attempts. Such a dual (combustible and electronic) cigarette use is common. It may be an interim state for people attempting to quit cigarette smoking, while its impact on smoking cessation is uncertain [99].

With sport, CBD and electronic cigarette as the methods most likely to be used for both tobacco and cannabis cessation, our results suggest, as Walsh et al. in the UK [35], that recourse to formal care and evidence‐based interventions is low among French young adults who co‐use. However, we found that around 50% of our sample were somehow likely to use nicotine replacement therapy for tobacco cessation. In contrast, the likelihood of being followed up by a health professional was very low for both substances.

Contrary to nicotine‐containing e‐cigarettes, which are effective for tobacco cessation [100, 101, 102], no consistent evidence supports the effectiveness of exercise interventions for tobacco cessation [103]. Evidence for CBD in reducing or quitting tobacco and cannabis use also remains limited [104]. Nevertheless, sport, CBD and vaping appear to be preferred by young adults and warrant further investigation as potential treatments for co‐use.

Existing evidence regarding these methods has rarely been drawn from the relevant population in terms of age and type of use. Although few studies have explored exercise for substance use treatment in youth [105], physical activity is expected to alleviate anxiety and depression and improve cognitive function among individuals with substance use disorders [106]. These benefits are particularly relevant given the burden of mental health conditions among European young people [107], which are strongly associated with both tobacco and cannabis use, as well as co‐use [16, 108, 109]. Emerging data also suggest that physical activity may be linked to lower risks of CUD [110, 111], and provide both behavioural and physiological rationales for further research [112]. Evidence supporting oral CBD for reducing cannabis or tobacco/nicotine use remains weak [113, 114, 115, 116], although vaping CBD may hold promise for cannabis use reduction [117].

There is therefore promising research perspective in testing and combining physical exercise, electronic cigarette and CBD (potentially with other types of interventions) to treat tobacco and cannabis co‐use in young adults. Indeed, each method presents rationale for such use, appeared acceptable for both substances, and could therefore be applied as a common strategy to quit tobacco and cannabis, either simultaneously or sequentially. Indeed, we have shown that, for a given method, the likelihoods of using it for both substances were correlated.

When looking at types of methods according to preferred cessation approach, we observed that participants preferring simultaneous cessation declared less methods they would be likely to use for cessation, and that they were more likely to declare none. This is consistent with the previously discussed interpretation of the results, suggesting that simultaneous cessation may be preferred by individuals with a lower‐risk profile of use, who therefore perceive less need for external resources to quit.

Between 20% and 30% of participants who had previously tried to quit (depending on the substance) reported using none of the listed cessation methods. High rates of unassisted tobacco quit attempts among young adults who co‐use were observed in the UK, where most still expected to seek support from their family doctor [35]. A qualitative study among young adults who co‐use electronic and combustion cigarettes in California also reported that “cold turkey” quitting was frequently tried for quitting either or both tobacco products [118]. In the US, young adults may also be less likely than older adults to use pharmacotherapy [57].

In France, qualitative studies are needed to understand why unassisted cessation is so likely among young adults who co‐use. Possible reasons include limited awareness of recommended methods, negative beliefs about treatments [119], barriers to care [120], preference for self‐reliance [121, 122] and cannabis‐related stigma [121, 122, 123]. Consistently, the cessation methods most often considered in our sample reflected this autonomy: professional or group support was rarely mentioned, while preferred strategies—such as alternative products or behaviours—could be implemented independently.

The major strength of the present study is its originality, as to our knowledge, preference for simultaneous versus sequential dual cessation had not been explored among people who co‐use so far. Those findings were extended by providing, for the same individuals, preferences for cessation strategies for both substances. Our results may therefore directly inform clinicians and also pave the way for future research on co‐use treatment.

Despite its nationwide implementation and gender balance, generalisability of our findings should be taken with caution, particularly given that the questionnaire was self‐administered, age was not verified, and no attention checks or bot detection mechanisms were applied. Our study sample was a convenient one and its modest size may have prevented some effects from being identified (e.g., non‐mixing participants were very few). The predefined list of quitting methods may have lacked exhaustiveness. For instance, technology‐based programmes may have warranted separate, dedicated items [124]. Additionally, some methods’ labels may have been interpreted differently by participants. For example, the term “sport” did not presuppose specific ways of appropriating physical activity—whether as a distraction, a source of motivation, or a means of managing withdrawal. Moreover, most participants were non‐treatment‐seeking and our results require replication in clinical samples.

To conclude, there was no overarching preference for simultaneous or sequential dual cessation in our sample of young adults who co‐used tobacco and cannabis. However, simultaneous cessation seemed preferred by participants with a low‐risk use profile, suggesting that feasible and effective sequential strategies need to be developed for people most in need for treatment. Future research should include acceptable strategies such as physical exercise, CBD and electronic cigarettes to identify effective means to accompany dual cessation in young adults.