How long does nicotine stay in your system if you are a heavy smoker?

Doesn't accumulate: Really doesn't matter that much if you are a heavy or light smoker. Nicotine is a very short-acting chemical and is only active in bloodstream for a few hours, then is converted to a metabolite cotinine that is metabolically inactive, but is what most drug tests look for. It sticks around in blood for 1-2 days, in urine for 2-4 days, oral swabs can pick it up a little longer, perhaps 3-5 days.