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Nicotine/Cotinine
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An_244613 posted:
How long before all traces of nicotine/cotinine are out of your blood?
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Jonathan Foulds, PhD responded:
Nicotine has an average "half-life" of 2 hours in the human body, but it can range from 1 to 4 hours in different people/circumstances. A VERY high blood nicotine concentration at the end of a smoking day might be 80 ng/ml. For the average smoker, therefore, the blood nicotine concentration will be down to negligible levels (<1ng/ml) within 24 hours. Cotinine has a typical half life in the range 16-24 hours, so it could take over a week for the cotinine level of a heavy smoker (could be over 500 ng/ml) to get down to the sorts of levels that could conceivably be caused by exposure to environmental tobacco smoke pollution (i.e. other peoples smoke). This all assumes the individual is not continuing to use any nicotine-containing products.