Most of the life insurance tests look for cotinine rather than nicotine. That's because the former is detectable in the system for a longer period of time than the former. As for how long cotinine can be detected in your system: that depends on two things. One is the the kind of tobacco product you use. The other is the type of test you take. For example, cotinine leaves the bodies of menthol cigarette smokers slower than it does people who smoke non-menthol cigarettes. Also, urine tests are more sensitive than saliva and blood tests when it comes to detecting cotinine in your system.