what happens after smoking one cigarette Many people think only on the weekends or at parties is harmless, but doctors warn there is no safe amount of tobacco. Find out how even occasional smoking damages your heart Chart: A Cigarette a Day

Venous stasis is another consequence when the valves in your veins dont allow blood to flow back up to the heart

Acknowledgements Where authors are identified as personnel of the International Agency for Research on Cancer/World Health Organization, the authors alone are responsible for the views expressed in this article and they do not necessarily represent the decisions, policy or views of the International Agency for Research on Cancer/World Health Organization

For international travel, consider edibles instead of vapes, as they're often subject to less scrutiny

A positive result often reflects metabolite presence rather than legality