Doctor reveals what happens when you smoke a single cigarette and impact it has on your body

Whether having a cigarette after a few drinks, a quick puff outside a pub garden, or that one friend who swears they only smoke when the sun’s out, the idea of being a ‘social smoker’ — but even having a rare one can still have an effect on your body.

With smoking rates falling across the UK, many see themselves as separate from the image of a daily smoker. It’s become normal to hear someone insist they’re basically a non-smoker, despite reaching for a lighter every now and then. Still, while the label might sound harmless, health experts have warned that even low-level smoking isn’t as casual as people think.

While there are some doctors sharing how to treat male infertility, another has revealed what actually happens inside your body when you smoke a single cigarette; the reality might make some rethink that ‘just one’ mindset.

Low-level smoking still delivers nicotine, carbon monoxide, and other toxic substances (skynesher/Getty Images)

Dr Suzanne Wylie, a GP who is also a medical adviser from IQdoctor, recently spoke to Metro and explained: how ‘the body does not distinguish between a daily smoker and someone who smokes intermittently’.

She said: “Each exposure to tobacco smoke delivers nicotine, carbon monoxide, tar, and a wide range of toxic chemicals that have immediate and cumulative effects. Research has shown that the cardiovascular system reacts almost immediately to tobacco smoke — even one cigarette.’

Doctor Wylie added that while ‘someone smoking 20 a day is at far greater risk’, the physical effects ‘begin with the very first cigarette.’

She went on to say:”‘If someone were to smoke a single cigarette, the immediate effects on the body would include a transient rise in heart rate and blood pressure, constriction of blood vessels, and a temporary reduction in oxygen delivery due to carbon monoxide exposure.”

Even occasional smoking can trigger immediate changes inside your cardiovascular system (SimpleImages/Getty Images)

The doctor has also touched on the longer-term concerns of smoking that also come into play: ”Even low-level smoking increases the risk of cancers of the lung, mouth, throat and oesophagus, and when combined with alcohol in social settings, the carcinogenic effects are amplified.”

However, it’s not all doom and gloom. She points out that ‘these changes are short-lived in a healthy person and the body will largely recover within hours to days — so one isolated cigarette is extremely unlikely to cause permanent measurable damage in an otherwise well individual. The cardiovascular system begins to improve within days to weeks of stopping.’

Still, the bigger issue may be habit formation. Dr Suzanne warns that ‘there is no safe threshold.’ She also explained: ‘Even though the absolute risk from a single event is very small, one exposure triggers inflammatory changes within the vascular lining and oxidative stress at a cellular level.’

Ultimately, she believes it’s not just about one cigarette in isolation, saying “Risk is not binary, and what concerns us clinically is not so much the one off cigarette, but the behavioural trajectory…‘Repeated “just one” scenarios can gradually shift into a pattern of intermittent or regular smoking, and it is that sustained exposure over years that meaningfully alters long term health outcomes.’