Medically reviewed by Amelia MacIntyre, DO Nicotine quickly enters your bloodstream. Your liver then breaks down nicotine into several byproducts, primarily cotinine. Depending on what you're testing, ...

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 ...