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Friday, March 7, 2014
Smoking and Tobacco
How long does it stay in your system?
You may be asking how long nicotine stays in your system after you use smokeless tobacco. Nicotine has a half-life of about 2 hours. That means that if you have a level of 20 (ng/ml) of nicotine at 9 pm after using smokeless during the day, that would decrease to 10 (ng/ml) at 11 pm and 5 (ng/ml) at 1 am and so on - IF you do not use more smokeless tobacco during that period.
There is a breakdown product of nicotine called cotinine (COAT-a-neen). Cotinine has a much longer half-life than nicotine. Its half-life is about 18 hours. So taking the same example above - if you have a cotinine level of 200 (ng/ml) at 9 pm it will decrease to 100 (ng/ml) by 3 pm the following day IF you do not use smokeless tobacco, and so on. Therefore, cotinine is used to measure nicotine exposure over time since it is stays in the body for longer periods.
Karen L Ahijevych, PhD, RN, FAAN
Professor, College of Nursing
Professor, College of Public Health
College of Nursing
The Ohio State University