Numerous studies confirm a far lower level of harmful constituents (see our Harmfulness section), but none has systematically tracked the everyday reactions of people who switch. From years of discussion in our user groups we have gathered what people actually report.
This article is a collection of subjective experiences, not a medical statement. Every reaction described affected individuals, never all users.
If you have symptoms, put the device down and talk to your doctor.
Coughing after the switch
You unbox the device, insert the first stick, take a draw – and cough. The warm vapour surprises almost everyone. Most newcomers draw as they would on a cigarette, hard and deep. IQOS works differently. Draw gently and slowly, with longer gaps between puffs. By the third stick at the latest the irritation settles.
The cough does not disappear immediately, though. The morning clear-out of cigarette phlegm is usually replaced by a light cough spread through the day, as the lungs gradually clean themselves.
As the cough fades, breathing improves noticeably – often within days. It is the most visible change of the whole switch.
Dry mouth, skin and acne
The warm vapour dries out the mouth and lips. That usually stays permanent, but it is easy to manage: simply drink more.
Women in particular occasionally report acne returning. Cigarettes dry the skin out; after switching the skin produces more oil again, which for some means breakouts. It normally settles within a few weeks.
Sensitive or bleeding gums
Some people report more bleeding when brushing. IQOS does not cause this; it tends to expose an existing problem. Smoking constricted the blood vessels in the gums, and now circulation is back to normal. Take it to a dentist – the underlying problem is there either way.
Headaches and an unsettled stomach
Especially at the start, some users report headaches and occasionally stomach discomfort, most often lighter smokers. All sticks contain around 0.5 mg of nicotine, similar to a cigarette – but because less nicotine burns away when tobacco is heated, you actually absorb more.
Nicotine demonstrably irritates the stomach and can cause dizziness or headaches. What helps: drink more, cut the quantity, and do not use the device on an empty stomach. The symptoms usually pass quickly.
Putting on weight
Nicotine speeds up the metabolism, and quitting smoking often means a few extra kilos in the short term. Switching to IQOS should not do that, since the nicotine intake continues. Plenty of people report it anyway.
The honest answer: switching is not quitting. You have already done your body a great deal of good – the rest is exercise, and one day perhaps leaving nicotine behind entirely.