Clinical studies

      Clinical studies on smoke-free products

      Clinical research is a cornerstone of our smoke-free product assessment program. Once a product has been demonstrated to release lower levels of harmful chemicals compared with cigarette smoke, and after it has also been demonstrated to be less toxic in laboratory studies, we can begin clinical studies. 

      Clinical studies are a cornerstone of smoke-free product assessment

      Our clinical studies touch on several areas of research involving human study participants. They are conducted by contract research organizations according to strict guidelines and ethics standards. Clinical studies help us understand how quickly nicotine is absorbed into the body, to know whether the product is acceptable to current adult smokers, and they can also provide information about the potential risk reduction on an individual level as a result of switching. Importantly, these products contain nicotine, which is addictive, and they are not risk free.

      Check the list of our clinical studies, including those studies that are in progress and may not yet have results available. Learn more about how our team of clinical scientists run these studies. All our clinical studies are registered on

      We consistently find that our clinical studies demonstrate the reduced-risk potential of smoke-free products compared with cigarettes, in line with our aerosol and toxicology study results. Still, understanding the relative risk to an individual who switches to a smoke-free product is only half of the equation considering the likely impact on population health. Learn more about our research on consumer perception and behavior. Quitting is the best choice. And for those adult smokers who don’t quit, choosing a scientifically substantiated better product can reduce their risk of developing smoking-related diseases. This is the impact we expect to see in our long-term assessments

      You can find a summary of our entire product assessment program in the PMI Science Booklet, and our publications, most of which are open-access, can be found via the publications library.

      Jump to a specific result from our clinical studies on  the Tobacco Heating System (THS):

      • Potentially reduced disease risk

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      • Lower level of exposure

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      • Nicotine uptake comparable to cigarettes

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      Clinical findings provide evidence on the potential of the Tobacco Heating System to reduce the risk of developing CVD, COPD, and cancer compared with continued cigarette smoking

      We conducted a 1-year exposure response study, which involved a 6-month study followed by a 6-month extension study focusing on smoking-related diseases, specifically cardiovascular disease (CVD), chronic obstructive pulmonary disease (COPD), and cancer. Eight biomarkers of potential harm (BoPH) were measured. Changes in these biomarkers can indicate changes to certain series of chemical processes (physiological pathways) that happen inside the body, and ultimately can signal potential harm to the body as a result. The BoPH that were selected are known to represent pathways that can be altered by cigarette smoking, and they are known to improve within 6 months of smoking cessation. We aimed to demonstrate favorable changes in all eight BoPH when smokers switch to THS versus continued smoking. To compare the effect of switching to THS with that of smoking cessation, we also conducted a 1-year smoking cessation study evaluating the same core set of eight BoPH. 

      Our studies showed that smokers who switched from cigarettes to THS for 12 months had favorable changes in all eight BoPH, in the same direction as smoking cessation. Among THS users who mostly used THS but also smoked cigarettes or used other products, the less cigarette smoking they did, the greater were the favorable effects on their BoPH. Considering all but the most intense cigarette use, THS users saw 67% of the effect of smoking cessation for seven of the eight BoPH. The results of the 6-month extension study have not yet been published in a peer-reviewed journal.

      Learn more about these clinical studies:

      Smokers switching completely to the Tobacco Heating System were exposed to lower levels of harmful chemicals compared with those who continued smoking

      In our 5-day and 90-day clinical reduced exposure studies, we measured biomarkers representing exposure to selected harmful chemicals in the blood and urine of study participants. We found that levels of 15 biomarkers of exposure in participants switching completely to THS were comparable to the levels of those who quit smoking for the duration of the study. For both the THS group and the cessation group, the levels of these biomarkers of exposure remained significantly below those observed in subjects who continued smoking during the study.

      Examine the clinical studies that support these conclusions:

      When switching to the Tobacco Heating System, the nicotine uptake and urge-to-smoke scores were comparable to those measured in subjects who continued smoking

      We have shown that the level of nicotine and the timing of its peak concentration in the blood were comparable for smokers and for subjects who switched to THS. Furthermore, the urge-to-smoke scores were similar for smokers and switchers. This suggests that switchers do not seek to use THS more frequently than smokers seek to use cigarettes, and that switchers can find THS acceptable and satisfying.

      Read the research on this topic: