Cotinine is a metabolite of nicotine that is produced after smoking tobacco. Cotinine will remain detectable in the body for up to one week, however, studies have shown that people who smoke menthol cigarettes have traces of cotinine in their system for longer periods that those who smoke regular cigarettes.

The level of cotinine present in the body is an indicator of how much or how little a person smokes tobacco. An amount of 10 ng/ml to 30 ng/ml would indicate light use of tobacco, whereas heavy use of tobacco can produce up to and above 500 ng/ml of cotinine in the body.