How Long Is Cotinine Detectable in a Urine Test?

Cotinine, the primary breakdown product of nicotine, is typically detectable in urine for about two to four days after the last exposure to tobacco or nicotine. Heavy or long-term smokers can test positive for up to a week or slightly longer, while someone who had a single cigarette at a party might clear the threshold in two days or less. That range exists because the detection window depends on more than just when you last smoked: your genetics, kidney function, hydration, hormonal status, and even the cutoff concentration the lab uses all play a role.

Why Cotinine and Not Nicotine

Nicotine itself vanishes from your body fast, with a half-life of roughly two hours. That makes it a poor marker for testing because the window is so short. Your liver converts most nicotine into cotinine, which lingers much longer, with a half-life of about 16 to 19 hours. That slower clearance gives labs a wider window to catch it. A portion of cotinine is further processed into other metabolites, and some of it is excreted as a glucuronide conjugate, a form where the body has tagged the molecule for removal through the kidneys. Those conjugates account for roughly 29% of the monitored urinary metabolites of nicotine in smokers.¹ Because cotinine sticks around and accumulates predictably, it has become the go-to biomarker for tobacco and nicotine exposure across clinical, insurance, and workplace settings.

What Counts as a Positive Result

There is no single universal cutoff for a “positive” urine cotinine test. The threshold a lab applies depends on the purpose of the test and the population being screened. In research and clinical practice, urine cotinine cutoffs commonly fall between 50 and 200 ng/mL for distinguishing active smokers from nonsmokers.² One large Korean population study settled on a cutoff of 164 ng/mL, which produced sensitivity above 93% and specificity above 95%.²

Insurance companies often set lower thresholds, sometimes as low as 50 ng/mL or even lower, to catch lighter or more recent use. The practical takeaway is that the same person with the same cotinine concentration could test “positive” under one organization’s standard and “negative” under another’s. If you are preparing for a specific test, the cutoff that matters is the one used by the entity ordering it, not some average from the literature.

For blood rather than urine, the threshold is generally lower. The current optimal plasma cotinine cut-point to separate smokers from nonsmokers in the general U.S. population sits at about 3 ng/mL.³ Urine concentrations run much higher than blood levels because the kidneys concentrate waste products, which is part of why urine cutoffs are set in the tens or hundreds of ng/mL rather than single digits.

How Heavily and How Often You Use Nicotine

The single biggest factor in how long cotinine shows up is how much nicotine you have been putting into your body and for how long. Cotinine builds up with repeated exposure. An occasional smoker who has a cigarette once a week maintains much lower baseline levels than a pack-a-day smoker whose body never fully clears one dose before the next one arrives. For someone who smokes daily, urine cotinine concentrations can be well over 1,000 ng/mL. By contrast, exclusive e-cigarette users tend to have median urine cotinine levels around 310 ng/mL, and people who both vape and smoke conventional cigarettes tend to have the highest levels of all, with median concentrations above 1,250 ng/mL.⁴

This matters for detection windows because the higher your peak level, the more half-lives it takes to drop below the cutoff. If a daily smoker’s urine cotinine is 1,200 ng/mL and the cutoff is 200 ng/mL, roughly three half-lives, or roughly two and a half to three and a half days, are needed just to fall below that line. But if the same person’s level is 2,000 ng/mL or higher, you are looking at four or more half-lives, potentially pushing the window past four or five days. That is why the “two to four days” estimate is a range, not a fixed number.

Genetic Variation in How Fast You Process Nicotine

Your liver’s CYP2A6 enzyme does most of the work converting nicotine to cotinine and then breaking cotinine down further. But not everyone’s CYP2A6 works at the same speed. Certain gene variants slow the enzyme down substantially, leading to markedly reduced clearance of both nicotine and cotinine.⁵ Researchers use the nicotine metabolite ratio, a measure of how quickly your body converts cotinine to its next breakdown product, as a stable marker of CYP2A6 activity.⁶

People with slow-metabolizer gene variants keep cotinine circulating longer, which extends the detection window and can also mean they smoke fewer cigarettes because each one delivers a more lasting nicotine effect. Fast metabolizers, on the other hand, break down cotinine quickly and may clear below a test cutoff sooner than average. The frequency of these gene variants differs across populations: certain slow-metabolizer alleles are more common in people of East Asian ancestry, while African American smokers carry a distinct set of variants that influence CYP2A6 activity.⁶ You cannot know your metabolizer status without genetic testing, but if you have always felt that nicotine hits you harder and lasts longer than it seems to for friends who smoke the same amount, a genetic difference in CYP2A6 is a plausible explanation.

Pregnancy Speeds Up Clearance

Pregnant women metabolize nicotine and cotinine much faster than the general population. Total nicotine clearance rises by about 60% during pregnancy, and cotinine clearance jumps by roughly 140% compared to the postpartum or nonpregnant state.⁷ This dramatic acceleration is driven by hormonal changes that upregulate the liver enzymes responsible for nicotine metabolism.

The clinical consequence is that standard cotinine cutoffs developed in general populations can misclassify pregnant smokers as nonsmokers. A pregnant woman who is actively smoking may produce a cotinine reading that falls below a cutoff calibrated for nonpregnant adults. One study found that pregnant women who smoked had median cotinine levels of about 99 ng/mL, while those using nicotine replacement therapy and staying abstinent from cigarettes showed median levels around 63 ng/mL.⁸ Both numbers are substantially lower than what a similarly heavy nonpregnant smoker would typically show, entirely because of faster metabolism.

Kidney Disease Slows It Down

On the opposite end of the spectrum, people with impaired kidney function eliminate cotinine more slowly. Since the kidneys are a major route for excreting cotinine and its conjugates, renal disease means the compound lingers in the body longer than usual. Research on patients with kidney failure has confirmed that cotinine elimination is decreased in this group.⁹ For someone on dialysis or with advanced chronic kidney disease, the practical detection window after last nicotine exposure could extend well beyond the typical three-to-four-day estimate.

Other factors also influence metabolism speed, though usually less dramatically. Nicotine metabolism is affected by diet and meals, age, sex, use of estrogen-containing hormones, and certain co-medications.³ Women of reproductive age who take oral contraceptives tend to metabolize nicotine somewhat faster due to the estrogen effect on CYP2A6 activity. Older adults generally process nicotine more slowly than younger adults. None of these shifts are as dramatic as the pregnancy or kidney-failure effects, but they all nudge the detection window in one direction or the other.

Secondhand Smoke and Low-Level Exposure

A question that comes up frequently is whether just being around smokers can trigger a positive cotinine test. The answer depends on how much secondhand smoke you are exposed to and what cutoff the test uses. Secondhand smoke does produce measurable urinary cotinine. In one study of nonsmoking individuals exposed to tobacco smoke, about 68% tested positive for cotinine, with the likelihood increasing based on how often and where they encountered the smoke.¹⁰

However, the concentrations from passive exposure are usually far lower than those from active smoking. Non-smokers living in the same household as a smoker might have urine cotinine levels of a few ng/mL, while the smoker’s levels are hundreds or thousands of ng/mL. Children living with smoking parents show higher cotinine concentrations than children in smoke-free homes, even when parents report no direct secondhand smoke exposure to the child.¹¹ This suggests that thirdhand residue on clothing, furniture, and shared indoor air contributes to nicotine absorption even when smoking happens elsewhere.

For most workplace or insurance tests with cutoffs in the 50 to 200 ng/mL range, casual secondhand exposure alone is unlikely to push you over the line. But if you spend hours each day in a small, poorly ventilated space with heavy smokers, or if the cutoff used is very low, a false classification becomes possible. A study of pregnant nonsmokers found that among those reporting secondhand smoke exposure, fewer than 5% actually had urinary cotinine above 40 ng/mL.¹² So while detectable, the amounts from passive exposure rarely mimic a smoker’s levels.

E-Cigarettes, Heated Tobacco, and Nicotine Replacement Therapy

Any product that delivers nicotine will produce cotinine in your urine. That includes vapes, heated-tobacco devices, nicotine patches, gum, and lozenges. The levels depend on how much nicotine the product delivers and how you use it. E-cigarette users generally show lower urine cotinine than conventional smokers, though their levels are still clearly elevated above nonsmokers.¹³ How much lower depends on the device, the nicotine concentration of the liquid, and how frequently the person vapes. Some modern high-nicotine pod systems deliver nicotine comparably to cigarettes, so the old generalization that vaping produces less cotinine is becoming less reliable.

Nicotine replacement therapy is designed to deliver controlled doses of nicotine without combustion. One study in pregnant women found that NRT produced median cotinine levels of about 63 ng/mL, compared to about 99 ng/mL while the same women were smoking.⁸ The drop makes sense because NRT products typically deliver less total nicotine per day than a pack of cigarettes. Still, NRT absolutely will produce a positive cotinine test. If you are using patches or gum as part of a quit attempt and face a cotinine test, the result will likely be positive, and you should disclose the NRT use.

Food, Tea, and the Possibility of Trace-Level Cotinine

Nicotine is a natural compound found in plants from the nightshade family, which includes tomatoes, potatoes, eggplant, and peppers. Some teas also contain small amounts. When you eat these foods, your body converts the dietary nicotine into cotinine, just as it would with tobacco-derived nicotine. Researchers have estimated that dietary nicotine from these foods could produce urinary cotinine concentrations somewhere between about 0.6 and 6.2 ng/mL, depending on how much you eat.¹⁴

Those are very small numbers. For a standard workplace or insurance test with a cutoff of 50 ng/mL or higher, a dinner heavy on eggplant parmesan is not going to trigger a positive. The concern is mainly relevant to researchers studying environmental tobacco smoke exposure, where they are looking at cotinine levels down in the single digits and trying to separate passive smoke inhalation from dietary background noise. For anyone facing a standard nicotine screening, food is not a realistic source of a false positive.

Hydration, Urine Concentration, and Why It Matters

Because urine testing measures the concentration of cotinine in a fluid sample, anything that changes how dilute or concentrated your urine is will affect the raw number the lab reports. If you are dehydrated, your urine is concentrated and cotinine readings will be higher. If you have been drinking large amounts of water, your urine is dilute and the reading drops, potentially falling below a cutoff even though the total amount of cotinine your kidneys excreted has not changed.

Labs are aware of this. The standard correction is to measure urinary creatinine alongside cotinine and adjust the result. Both creatinine and specific gravity are significant predictors of urine concentration and improve the accuracy of cotinine measurements.¹⁵ The method of adjustment matters: a regression-based correction for creatinine significantly improves the correlation between urine cotinine and blood cotinine levels, while a simple ratio of cotinine to creatinine does not perform as well.¹⁶ The takeaway for the person being tested: intentionally over-hydrating before a test to dilute cotinine is not a reliable strategy, because a competent lab will either adjust for dilution or flag a specimen with abnormally low creatinine as suspect.

How Long Samples Last Before Testing

If you are wondering whether the timing between giving a urine sample and the lab running the analysis could affect your result, the answer is generally no, within reason. Cotinine in urine is chemically stable. Research has found that cotinine concentrations in urine samples do not change significantly for up to 30 hours at room temperature or up to eight days when frozen at −25°C.¹⁷ Standard shipping and handling timelines for lab specimens fall well within those windows, so degradation of the sample during transit is not something that would meaningfully alter a test result.

Rough Timelines by Scenario

Pulling together the pharmacology and the modifying factors discussed above, here are approximate detection windows for urine cotinine under a common cutoff in the 50 to 200 ng/mL range. These are rough guides, not guarantees, because individual variation in metabolism is real:

One-time or rare use: Cotinine typically drops below standard cutoffs within one to three days.
Light daily smoking: Expect the window to be about three to four days, possibly a bit longer if you are a slow metabolizer.
Heavy daily smoking: Because baseline levels are so high, it can take five to seven days or occasionally slightly longer for cotinine to clear below the cutoff.
E-cigarette use: Detection times are similar to smoking but often a day or so shorter, reflecting the lower nicotine delivery of many devices. Heavy use of high-nicotine vape systems can match cigarette-level detection windows.
Nicotine replacement therapy: Active patch or gum use produces ongoing cotinine, so the clock only starts once you stop using the product. After stopping, expect two to four days.
Pregnancy: Faster metabolism may shorten these windows by roughly a day, though the effect varies.
Kidney disease: All windows potentially extend by a day or more, depending on severity.

Hair and Saliva as Alternatives

Urine is the most common matrix for cotinine testing, but it is not the only one. Saliva cotinine tests use cutoffs generally in the 10 to 25 ng/mL range and have a detection window roughly similar to urine.² Hair testing is a different animal entirely. Because nicotine and cotinine are incorporated into the hair shaft as it grows, hair analysis can detect tobacco use months after the last exposure, depending on hair length. This makes hair tests useful for verifying long-term abstinence but useless for capturing a recent one-time slip. Blood tests, meanwhile, tend to have the shortest practical detection window of the common methods, since plasma cotinine levels drop faster than urinary concentrations.

Each matrix has tradeoffs. Urine is easy to collect, has a good multi-day detection window, and has well-studied cutoff values. Saliva is noninvasive and correlates well with plasma levels. Hair captures the long view but cannot tell you whether someone smoked last week versus three months ago. The choice of test depends on the question being asked: recent exposure, ongoing use, or historical abstinence.

1
PubMed. Evidence for urinary excretion of glucuronide conjugates of nicotine, cotinine, and trans-3′-hydroxycotinine in smokers
2
PubMed Central. Overview of Cotinine Cutoff Values for Smoking Status Classification – Section: 3.3. Urinary Cotinine
3
PubMed Central. Nicotine chemistry, metabolism, kinetics and biomarkers
4
PubMed Central. Differences between the effects of conventional cigarettes, e-cigarettes and dual product use on urine cotinine levels
5
PubMed Central. Disposition kinetics and metabolism of nicotine and cotinine in African American smokers: impact of CYP2A6 genetic variation and enzymatic activity
6
PubMed. Fine-mapping the CYP2A6 regional association with nicotine metabolism among African American smokers
7
International Journal of Hygiene and Environmental Health. Urinary cotinine cut-offs for tobacco smoke exposure in pregnancy and associations with child intelligence quotient: A multi-cohort analysis
8
PubMed Central. Comparison of cotinine levels in pregnant women while smoking and when using nicotine replacement therapy
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PubMed. Pharmacokinetics of nicotine in kidney failure
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JURNAL KEDOKTERAN. Identification of Urine Cotinine in Secondhand Smoke and its Association with Socio-Environmental
11
PubMed Central. Biomarker-questionnaire discordance in secondhand smoke exposure among Korean children: A secondary analysis of the Korean National Environmental Health Survey, 2016-2017 and 2019-2020
12
PubMed Central. Self-Reported Exposure to Second-Hand Smoke and Positive Urinary Cotinine in Pregnant Nonsmokers
13
PubMed Central. Comparison of Nicotine Dependence and Biomarker Levels among Traditional Cigarette, Heat-Not-Burn Cigarette, and Liquid E-Cigarette Users: Results from the Think Study
14
PubMed. Dietary nicotine: a source of urinary cotinine
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PubMed Central. A comparison of creatinine vs. specific gravity to correct for urinary dilution of cotinine
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Clinica Chimica Acta. How should urinary cotinine concentrations be adjusted for urinary creatinine concentration?
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PubMed. Urine collection for nicotine and cotinine measurement in studies on nicotine addicts