The harms of smoking are usually associated with a lifetime of use, but new research suggests that early exposure to nicotine can leave a mark on the immune system long before adulthood. In experiments with mice, scientists found that nicotine encountered early in life altered the way the immune system developed, leaving the animals less able to fight off influenza later on.
The study adds to mounting evidence that the period during which the immune system matures is uniquely vulnerable to disruption. Rather than simply causing short-term harm, early nicotine exposure appeared to reprogram immune responses in a way that persisted, making subsequent infections more severe. The implications reach beyond tobacco: nicotine is also delivered through vaping and oral pouches, products that have grown rapidly in popularity among young people. If the same effects occur in humans, early nicotine use could quietly weaken a generation's defences against ordinary infections. Researchers caution that the work was conducted in animals and cannot be directly applied to people, but the pattern is troubling enough to warrant serious attention.
