What this test measures
Cotinine is the primary metabolite of nicotine and has a much longer half-life (~16 hours in serum, longer in urine) than nicotine itself (1–2 hours). This makes cotinine the standard biomarker for tobacco / nicotine exposure over the previous 1–3 days. Available in serum, urine and saliva. Specific quantitative assays distinguish active smoking (typically > 10 ng/mL serum cotinine) from passive smoke exposure (1–10 ng/mL) from no exposure (< 1 ng/mL).
Why it matters
Common clinical uses in India: pre-bariatric and pre-transplant evaluation (some programmes require negative cotinine), insurance medicals, return-to-work assessments, smoking cessation programmes to verify quit, paediatric clinics evaluating respiratory symptoms in second-hand smoke exposed children, and academic research. Nicotine replacement therapy (gum, patches, lozenges) raises cotinine — verify the test ordered does not specify "tobacco-specific markers" if NRT is in use.
How to prepare
No fasting required. Random sample. Disclose nicotine replacement therapy (gum, patches, lozenges, vapes), passive smoke exposure, and consumption of chewing tobacco / gutka / paan-masala (which can produce very high levels). Saliva and urine sampling are non-invasive options.
Markers & reference ranges
Reference ranges below are typical adult values. Your lab's reported range may differ slightly based on the assay platform and patient demographics — always read your report against the range printed on it.
| Marker | Normal range | If low | If high |
|---|---|---|---|
| Serum Cotinine (ng/mL)[1][2] | Non-user / no exposure: < 1; Passive smoke: 1 – 10; Active smoker: > 10 | < 1 ng/mL: no recent nicotine exposure — consistent with a non-smoker without significant passive exposure. | 1 – 10 ng/mL: passive (second-hand) smoke exposure; review household environment. 10 – 100: active smoking, modest. 100 – 300: typical active heavy smoker (10 – 20 cigarettes/day). > 300: heavy smoker / smokeless tobacco / very high NRT use. |
Cotinine bands and interpretation
| Cotinine (ng/mL serum) | Status | Interpretation |
|---|---|---|
| < 1 | No exposure | Non-smoker; no significant second-hand |
| 1 – 10 | Passive smoke | Second-hand exposure (household / workplace) |
| 10 – 100 | Light active | Occasional or light daily smoker |
| 100 – 300 | Moderate–heavy | Daily smoker 10–20 cigarettes/day |
| > 300 | Heavy | Heavy smoker, smokeless tobacco, or high-dose NRT |
Frequently asked questions
Will nicotine gum or patches give a positive test?
Yes — nicotine replacement therapy produces cotinine. Tobacco-specific markers (NNAL, anatabine) can distinguish NRT from real tobacco use if the question matters (insurance, transplant).
How long does cotinine stay positive after quitting?
Serum cotinine typically falls below 10 ng/mL within 3–5 days of complete cessation and below 1 ng/mL by 2 weeks. Hair cotinine reflects exposure over months.
Will vaping cause a positive test?
Yes — vaping (with nicotine-containing e-liquids) produces cotinine indistinguishable from cigarette smoking on standard tests.
Does chewing tobacco / gutka affect this test?
Yes — and often more strongly than cigarettes because absorption is steady. Heavy gutka / paan-masala users may have cotinine levels > 500 ng/mL.
Can second-hand smoke really raise cotinine?
Yes — significantly. Cohabiting with a smoker typically produces serum cotinine of 1–5 ng/mL in non-smokers. This is the basis for using cotinine to track second-hand smoke exposure in children with asthma.
Will lab values differ across blood, urine, saliva?
Yes — urine cotinine is roughly 6× higher than serum at steady state, and saliva is roughly equal to serum. Most labs report a single threshold within the chosen matrix.
Related Toxicology / Trace Elements tests
Tests commonly ordered alongside COTININE, or that help interpret an unexpected result.
Sources & references
- CDC — Cotinine Biomonitoring · accessed 2026-05-30T00:00:00.000Z
- Mayo Clinic Labs — Cotinine, Serum · accessed 2026-05-30T00:00:00.000Z
- SRNT — Cotinine as biomarker of tobacco exposure · accessed 2026-05-30T00:00:00.000Z
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