Urine, saliva, blood and hair can all be tested to detect nicotine and cotinine.4 Different testing methods can detect whether you’ve had long-term exposure to nicotine products, as well as how much. Cotinine can be found in blood plasma, saliva and urine. It can typically be detected in these three mediums for three to four days after stopping smoking. Because traceable levels of cotinine do not remain in the body for an extended amount of time, testing for cotinine is useful for measuring the amount of nicotine the body is exposed to, but not necessarily for how long.1 Tests to the hair and nails can be used to determine long-term exposure to nicotine and cotinine. This is because these chemicals are incorporated into hair and nails as they grow. Traces of nicotine and cotinine can be detected several months after smoking a cigarette or other exposure to nicotine.1