The Cotinine test is a blood test that measures the level of cotinine, the primary metabolite of nicotine, in the bloodstream. When nicotine enters the body through cigarette smoking, smokeless tobacco use, nicotine replacement therapy, or passive exposure to tobacco smoke, the liver metabolises approximately 70 to 80 percent of absorbed nicotine into cotinine through the action of the cytochrome P450 enzyme CYP2A6. Unlike nicotine itself, which has a very short half-life of approximately one to three hours, cotinine has a significantly longer half-life of 16 to 20 hours, making it a far more stable, sensitive, and reliable biomarker for assessing both active tobacco use and secondhand smoke exposure over a clinically meaningful window of two to four days preceding the test.
Cotinine measurement is considered the gold standard biological marker for tobacco exposure, offering significant advantages over self-reported smoking history, which is frequently inaccurate due to underreporting driven by social desirability bias, insurance implications, or employment concerns. The test can accurately distinguish between active smokers, individuals exposed to significant secondhand smoke, users of nicotine replacement products, and true non-smokers with no meaningful nicotine exposure, making it uniquely valuable across clinical, occupational health, insurance, and public health contexts.
In India, tobacco use remains one of the most serious public health crises, with over 267 million tobacco users according to the Global Adult Tobacco Survey, encompassing cigarette smokers, bidi smokers, and a vast population of smokeless tobacco users consuming products including gutkha, khaini, and zarda. Secondhand smoke exposure is also widespread in Indian households and workplaces. The Cotinine test provides an objective and legally defensible measure of tobacco exposure that self-reporting cannot match. The test is performed on a small blood sample drawn from a vein and completed in under five minutes.