smoking facts

Can a Blood Test Detect Nicotine?
Testing on Blood and Urine Samples by Measuring Cotinine Levels

Q - Can a blood test detect nicotine?

A - YES, a blood test detects nicotine metabolites such as cotinine.

Testing for nicotine is most commonly done by private insurance companies who offer better life insurance rates to non-smokers.

Researchers will also test for cotinine in the blood or urine to determine the relationship between nicotine exposure and smoking related diseases.

Nicotine Half Life

Nicotine half life is about 2 hours. This means that 2 hours after you smoke a cigarette about half the nicotine has left your body and within about 2 hours after that the levels (from that last cigarette) are reduced by half again.

If you are a heavy smoker, 2 hours without a cigarette is a long time and chances are you have already reached for another cigarette by the time the nicotine levels in your body have been reduced by half.

For How Long Can a Blood Test Detect Nicotine in Your Body?

Nicotine should disappear from your system within about 72 hours. However, many factors influence the rate at which your body can get rid of it. Your age, size and general health condition may affect the body's clearing time. This time period may be prolonged if you are older and a heavy smoker.

The amount of nicotine also affects how quickly it disappears from your system. For heavy smokers, nicotine can be detected for much longer because there is much more of it stored in the body's cells and if you are not in really good health this may also lengthen the clearing time.

How long nicotine can be detected in your system also depends on how much of it has been converted to cotinine as cotinine has a longer half life.

It takes 24 hours for cotinine in your system to be reduced by half. If you continue to smoke there will always be cotinine in your urine. This is proof that there has been nicotine in the bloodstream within the last 24 hours.

Testing for Nicotine or Cotinine?

The body has many mechanisms to break down chemicals so they can be excreted. Many times these mechanisms change the chemical into something else so it is more easily eliminated by the body's normal excretion mechanisms such as the liver and the kidneys.

In the case of nicotine it is broken down into a metabolite called cotinine. The amount of this chemical in your blood or urine is an indication of the amount of nicotine exposure.

If you are using nicotine replacement products of any sort for quitting smoking, cotinine will be detectable in your bloodstream or your urine.

Why would a nicotine blood test be done?

If you are a non smoker seeking lower life insurance premiums, a private insurance company may do testing to validate your non-smoking status.

Many research studies do testing for nicotine metabolites in the bloodstream and the urine to determine the relationship between exposure to cigarette smoke and the health effects of smoking cigarettes. Such studies have helped identify the various diseases caused by smoking and the dose response relationship.

Furthermore, studies on cotinine levels in the urine have shown that secondhand smoking can result in significant exposures to nicotine. These studies have contributed to the body of evidence about the effects of environmental tobacco smoke, especially concerning children and the effects of cigarettes and smoking behaviour of parents.

So the short answer to the question "Can a blood test detect nicotine in your body?" is


But more commonly it is a nicotine urine test and it is the cotinine metabolite that is usually measured.

by Beverly OMalley

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