It's less smoke, not no smoke. A cigarette burns tobacco near 900 °C. IQOS heats a stick to about 320–350 °C, hot enough for a nicotine aerosol, too cool to trigger most combustion. A smoker who switches fully drops carcinogens like NNK, benzene, and butadiene by 70 to 95 percent within weeks 1 2. But it's still incomplete combustion. Analyses find the chemical fingerprint of smoke in the aerosol 3, and eighty constituents run higher than in cigarette smoke 4. So: much less of the chemicals linked to cancer, plus a smaller panel nobody can grade yet.
The exposure drops. The proof it protects you doesn't exist. On twenty-three of twenty-four biomarkers of actual biological harm, IQOS users at six months looked no different from continued smokers 5. Six months is short and the samples small, so nobody knows if that gap is real or just unmeasured yet. Nobody has used one for thirty years; the device launched in 2014. The one population signal is Japan, where cigarette sales went from a 3-percent yearly decline to a 16-percent one as IQOS spread 6 7. The catch: most Japanese users still smoke cigarettes too.
Whether this is for you depends entirely on where you're starting.
If you fully switch, here's the arc. First week: the smell on your clothes and breath stops, taste and smell partly return, carbon monoxide in your blood falls to baseline within days. A month or two: the morning cough fades. By week 8 to 12 your urinary carcinogen biomarkers sit 70 to 95 percent below a smoker's, near never-smoker levels on several 1. By a year exercise tolerance has partly rebuilt, though each session still raises heart rate and stiffens vessels 8. By a decade, the part nobody has measured, your outcome sits somewhere between a quitter's and a smoker's. The asterisk that stays: you're still using nicotine, and most switchers never stop.
The fine print — when to skip it, and what people get wrong
What the marketing softens. "FDA approved as safer" is false: the agency cleared a reduced-exposure claim and refused any reduced-risk one 9; the WHO regulates it as ordinary tobacco 10. "Smoke-free" and "basically a vape" both overclaim: it burns real tobacco chemistry a vape doesn't touch 3.
When it's not on the table. Pregnancy: nicotine harms fetal brain and lung development, so this is no safe swap; ask a midwife about nicotine-free cessation. Unstable heart disease: even one session raises heart rate and stiffens vessels 8.
Where it goes wrong. Dual use, keeping cigarettes alongside the device, is the common pattern and erases the biomarker gains 6. Symbolic substitution, buying it to feel like quitting is underway without quitting, is cover, not cessation.
- 1Lüdicke F, Picavet P, Baker G, Haziza C, Poux V, Lama N, Weitkunat R (2018). Effects of Switching to the Tobacco Heating System 2.2 Menthol, Smoking Abstinence, or Continued Cigarette Smoking on Biomarkers of Exposure: A Randomized, Controlled, Open-Label, Multicenter Study in Sequential Confinement and Ambulatory Settings (Part 1). Nicotine & Tobacco Research. link
- 2Mallock N, Böss L, Burk R, Danziger M, Welsch T, Hahn H, Trieu H-L, Hahn J, Pieper E, Henkler-Stephani F, Hutzler C, Luch A (2018). Levels of selected analytes in the emissions of "heat not burn" tobacco products that are relevant to assess human health risks. Archives of Toxicology. link
- 3Auer R, Concha-Lozano N, Jacot-Sadowski I, Cornuz J, Berthet A (2017). Heat-Not-Burn Tobacco Cigarettes: Smoke by Any Other Name. JAMA Internal Medicine. link
- 4Uguna CN, Snape CE (2022). Should IQOS Emissions Be Considered as Smoke and Harmful to Health? A Review of the Chemical Evidence. ACS Omega. link
- 5St Helen G, Jacob P 3rd, Nardone N, Benowitz NL (2018). IQOS: examination of Philip Morris International's claim of reduced exposure. Tobacco Control. link
- 6Cummings KM, Nahhas GJ, Sweanor DT (2020). What Is Accounting for the Rapid Decline in Cigarette Sales in Japan? International Journal of Environmental Research and Public Health. link
- 7Stoklosa M, Cahn Z, Liber A, Nargis N, Drope J (2020). Effect of IQOS introduction on cigarette sales: evidence of decline and replacement. Tobacco Control. link
- 8Biondi-Zoccai G, Sciarretta S, Bullen C, Nocella C, Violi F, Loffredo L, Pignatelli P, Perri L, Peruzzi M, Marullo AGM, De Falco E, Chimenti I, Cammisotto V, Valenti V, Cavarretta E, Carrizzo A, Prati F, Carnevale R, Frati G (2019). Acute Effects of Heat-Not-Burn, Electronic Vaping, and Traditional Tobacco Combustion Cigarettes: The Sapienza University of Rome-Vascular Assessment of Proatherosclerotic Effects of Smoking (SUR-VAPES) 2 Randomized Trial. Journal of the American Heart Association. link
- 9U.S. Food and Drug Administration (2020). FDA Authorizes Marketing of IQOS Tobacco Heating System with 'Reduced Exposure' Information. link
- 10World Health Organization (2023). Heated tobacco products: summary of research and evidence of health impacts. link
Heated Tobacco (IQOS)
Minor daily friction — keeping a holder charged, refilling sticks. No active protocol beyond purchase and use; a full-switch attempt adds a short evaluation window but no structured taper.
Starter kits ~$50–100; tobacco sticks $4–8 per pack of 20, putting pack-a-day use at $30–80/week — comparable to cigarettes in most markets, sometimes slightly cheaper in high-tax jurisdictions.
Biomarker-of-exposure reductions of 70–95% for headline carcinogens (NNAL, benzene, 1,3-butadiene, CO) on full switching from cigarettes (Lüdicke et al. 2018; Mallock et al. 2018) imply substantial harm reduction; no long-term incident-disease cohort exists, and 23 of 24 biomarkers of potential harm did not differ from continued smoking at 6 months in PMI's own data (St Helen et al. 2018). Zero or negative effect in never-smokers.
Biomarker-of-exposure side is strong and replicated (Lüdicke et al. 2018; St Helen et al. 2018; Mallock et al. 2018); cessation-outcome side is essentially absent — the Cochrane review (Tattan-Birch et al. 2022) found 13 studies and zero that reported cessation as an outcome; long-term disease-incidence cohorts do not yet exist. All randomised trials in the evidence base are tobacco-industry-funded.
Full-switchers from cigarettes report morning-cough improvement at 2–8 weeks, smell on clothes/breath gone within days, partial restoration of taste/smell; effect smaller and slower than full cessation, and zero for dual users (Lüdicke et al. 2018; St Helen et al. 2018).
For a current smoker who fully substitutes IQOS for cigarettes, the chronic combustion-vasoconstriction-and-staining trajectory halts; long-term facial-aging delta vs. continued smoking is real but mediated through cessation of combustion, not through the HTP itself. Zero benefit for never-smokers.
Acute nicotine alertness effect, similar magnitude to other nicotine vehicles; in ex-smokers, gradual restoration of exercise capacity once combustion exposure ceases. Modest and largely substitution-mediated.
Inhaled nicotine produces a small acute attentional / reaction-time lift; in chronic users the effect is largely withdrawal-relief rather than a true baseline shift, mirroring the cigarette and vape literatures.
Acute nicotine produces a small calming/lift via nAChR-mediated dopamine release; in chronic users this is mostly withdrawal management. Same pattern as cigarettes and vaping.