Can a blood test detect smoker and for how long after smoking?

Yes. A blood test can detect whether someone has been smoking and how long it has been since their last cigarette.

When a person smokes, nicotine and other chemicals from the cigarettes are absorbed into the bloodstream. These substances are then broken down by the body and excreted in urine and saliva. However, some of these chemicals can remain in the blood for several days after smoking.

Blood tests for smoking typically measure the levels of cotinine, a chemical that is produced when the body breaks down nicotine. Cotinine levels can be detected in the blood for up to 10 days after smoking. Some tests can even detect cotinine levels for up to 30 days after smoking.

Blood tests for smoking can be used for a variety of purposes, such as:

To help people quit smoking

To monitor compliance with smoking cessation programs

To identify people who are exposed to secondhand smoke

To research the health effects of smoking

Blood tests are not the only way to detect smoking. Other tests, such as urine tests and saliva tests, can also be used to detect nicotine and other chemicals from cigarettes.