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Smoking and Tobacco

How long?



How long does tobacco stay in your system?


Nicotine is one of the main parts of tobacco that is measured and can be described over time.  The half-life of cotinine, the major breakdown product of nicotine, is 20 hrs.  This means that whatever the amount of cotinine in your system at the time you stop smoking, it will decrease to 1/2 in 20 hrs, and so on.  For example, if you have a cotinine level of 400 ng/ml in your system and you quit smoking, that will decrease to 200 ng 20 hrs later; and decrease further to 100 ng in an additional 20 hrs, etc.  Depending what level you start at - it may take 4 days before this product leaves your system.  Other parts of tobacco may stay in the system longer.  Nicotine and its breakdown products are the ones most commonly measured. 

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Response by:

Karen L Ahijevych, PhD, RN, FAAN Karen L Ahijevych, PhD, RN, FAAN
Professor Emeritus
College of Public Health
College of Nursing
The Ohio State University