Nicotine quickly enters your bloodstream. Your liver then breaks down nicotine into several byproducts, primarily cotinine. Depending on what you're testing, such as a blood, urine, saliva, or hair ...

Nicotine itself could clear from your body in a few hours, but its byproduct can linger for days or weeks. Most nicotine tests detect cotinine, which can show up in urine, saliva, blood, hair, and ...