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Whenever you smoke or chew tobacco or inhale secondhand smoke from a cigarette, nicotine is absorbed into your bloodstream.

From there, enzymes in your liver break most of the nicotine down into cotinine. The amount of cotinine will increase with the amount of nicotine you ingest. These substances are eventually eliminated through your kidneys as urine.

Cotinine, nicotine’s main breakdown product, may be used to determine if someone was exposed to nicotine.

According to a 2016 review of literature, cotinine has high sensitivity and a longer half-life compared to other breakdown products of nicotine. Testing for it can usually differentiate people who smoke cigarettes from people who may have had indirect exposure.

How long it stays in your system will depend on how you ingested the nicotine and how frequently it is ingested.

Keep reading to learn how long nicotine can be detected in your urine, blood, saliva, and hair.

Q:

If I smoke one cigarette, how much nicotine will I ingest?

Anonymous patient

A:

1 milligram (mg) of nicotine per cigarette

Answers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.

Cotinine has a half-life of about 16 hours, according to the Centers for Disease Control and Prevention (CDC). However, it may be as long as 40 hours, according to a 2016 research review. A half-life refers to the number of hours before half of the cotinine will have left your system.

However, tests for this metabolite can detect cotinine even after it has reached this point.

Concentrations of cotinine in urine are about 4 to 6 times higher than in blood plasma or saliva.

A 2019 study used cotinine urine tests on people preparing for bariatric surgery to determine adherence to pre-surgery instructions. According to the study’s authors, the cotinine urine test provided high sensitivity and specificity for smoking in at least the previous 72 hours.

Another study from 2020 found that cotinine may still be detectable in urine for at least 8 weeks.

However, the way each person’s body metabolizes nicotine to create cotinine is different. Genetic differences can also affect the amount of time cotinine is detectable in your body.

According to research summarized by the CDC, non-Hispanic Black Americans may metabolize cotinine more slowly than non-Hispanic white Americans.

A positive urine test can depend on when you provide a urine sample relative to the last time you ingested nicotine. If you’re a current smoker, the test show urine cotinine levels of 1,000 to 8,000 ng/mL.

People who smoke but go 2 weeks without nicotine exposure before testing may show urine cotinine levels of less than 50 ng/mL.

Each lab may have different reference ranges for positivity, so it’s important to discuss the results with a doctor or technician.

People with heavy exposure to secondhand smoke may test at levels between 1 and 10 ng/mL.

Nicotine can be measured in your blood and saliva, but because cotinine has a longer half-life, testing for cotinine is typically preferred. According to 2016 research, the half-life of cotinine is the same whether tested for in your blood plasma, urine, or saliva.

However, all of these molecules have different cut-off points for detection. Some sources estimate that it may be detectable at least 3 days after exposure.

A 2012 review that looked at methods for assessing environmental exposure to cigarette smoke found that blood cotinine levels may reach their half-life in less than 1 day.

Saliva and blood have a lower concentration of cotinine than urine. The amount of cotinine in your saliva or blood may reach cut-off levels for detection sooner than testing using urine samples.

The exact length of time that cotinine is detectable in your blood may vary depending on your genetic makeup and the amount of nicotine that you were exposed to. Testing with blood may also be less sensitive than testing with urine. This could lead to false negatives or positives.

Nicotine in your blood can be detected using tests that are qualitative (whether or not nicotine is present) and quantitative (how much nicotine is present). These tests can detect nicotine, cotinine, and another breakdown product called anabasine.

Traces of nicotine can generally be found in your hair follicles for up to weeks, months, or even years after your last exposure, according to a 2021 review of literature. This can depend on the hair test administered as well as genetic factors.

But the authors of the review suggest that the results of hair testing may not correlate with blood testing. Hair testing may also show passive or environmental exposure to tobacco smoke.

Although hair testing is possible, it is not used as frequently as urine, saliva, or blood testing.

Q:

How can I determine how much nicotine is in my system? Are there tests that I can do at home?

Anonymous patient

A:

Yes, there are over-the-counter tests that can measure nicotine in either saliva or urine.

Answers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.

How long nicotine stays in your system can vary from person to person. Depending on your individual circumstances, nicotine may flush from your system sooner or even last longer.

According to 2010 research, the following factors may influence how long nicotine and its metabolites are detectable in your system:

  • How much you smoke. The amount of cotinine in your urine is correlated with your nicotine exposure.
  • Your genetic makeup. Each person metabolizes cotinine differently. According to the CDC, non-Hispanic Black people may metabolize cotinine more slowly than non-Hispanic white people.
  • Liver function. Cotinine is oxidized by the liver. Depending on your liver function, you may metabolize cotinine at a different rate.
  • Age. If you’re over 65 years old, your body may take longer to clear nicotine.
  • Diet and medication. Because clearing nicotine depends on your liver, the researchers predict that meals and medications may affect how your body processes nicotine.
  • Sex and hormonal differences. According to the 2010 research, which classified individuals as men and women, nicotine clearance and cotinine were higher in women. They also found that using oral contraceptives increased clearance as well.
  • Kidney function. Kidney failure can decrease the rate at which the body clears nicotine and cotinine.

The best way to clear nicotine out of your system is to avoid tobacco products. If you smoke, consider quitting. This way, cells in your body can focus on breaking down nicotine and removing it.

There are several things you can do to speed up this process:

  • Drink water. When you drink more water, more nicotine is released from your body through urine.
  • Exercise. This increases your body’s metabolism rate, which may lead you to clear nicotine faster. Sweat released through exercise takes nicotine and its byproducts with it.
  • Eat foods rich in antioxidants. Antioxidants can help boost your body’s metabolism rate. Options can include oranges and carrots. These foods also contain compounds like fiber.

Nicotine is the primary addictive component in cigarettes.

In small doses, nicotine can act as a stimulant, similar to coffee or cocaine. When ingested in larger quantities, nicotine becomes a relaxant. It may decrease tension and anxiety.

Ingesting smaller amounts of nicotine or abstaining from nicotine entirely can cause symptoms of withdrawal.

Symptoms of withdrawal can include:

  • intense desire for tobacco
  • increased hunger
  • fatigue
  • lack of concentration
  • headache
  • constipation
  • nausea
  • diarrhea
  • irritability
  • anxiety
  • depression
  • insomnia

Your symptoms may be most intense in the first few hours after smoking your last cigarette. These symptoms often lessen in severity after the first 3 days of being smoke-free.

Your individual symptoms and their potential duration depend on several factors, including:

  • how long you’ve been smoking
  • the type of tobacco products you used
  • how much you smoke on a day-to-day basis

If you would like to quit smoking, over-the-counter and prescription medications may help.

Nicotine replacement therapies (NRTs), such as nicotine patches, can help ease withdrawal symptoms as you decrease the amount of nicotine ingested over time.

According to Smokefree.gov, which was created by the National Cancer Institute, using an NRT doubles your chances of quitting completely. If you opt to use an NRT, you’ll still have detectable amounts of nicotine in your body until you cease all nicotine exposure.

Combining an NRT with a nicotine patch may be more effective than either product on its own.

If you smoke, traces of nicotine can be found in your hair, blood, urine, and saliva. It can be detected in your urine for at least 3 days after your exposure to nicotine and in your hair for weeks or more.

The best way to remove nicotine from your body is to avoid tobacco products altogether.