What is Nicotine?
Nicotine, an alkaloid found in the leaves of tobacco plant, is an exceptionally addictive substance and is the active component of tobacco smoke. The crucial question for smokers and healthcare workers is: How long does nicotine stay in your system? Tobacco leaves contain around two to seven percent nicotine. Nicotine imitates the effects of the neurotransmitter acetylcholine and has serious effects on the autonomic nervous system. It can cause paralysis and respiratory failure even at doses that are below 50 mg. 
The tobacco plant is a member of the Solanaceae family.  Biosynthesis of nicotine occurs in the roots. It is carried to the leaves for storage. The purpose of nicotine is to help protect the plant from insects.
Five percent of tobacco plant’s dry weight is nicotine. Depending on the brand, one cigarette may have eight to twenty milligrams of nicotine. The typical inhaled dose is about 3 mg . But only about one milligram is absorbed by the body. Even at this dose, nicotine affects the central nervous system and can cause:
- constriction of blood vessels,
- tachypnea (very rapid breathing),
In the United States, nicotine is a widely used and addictive drug. According to the National Household Survey on Drug Abuse, approximately 62 million individuals from age twelve and up are cigarette smokers – that’s about 29% of the US population.
Worldwide, around one-third of the adult male population smokes. Everyday around 80,000 to 100,000 children start smoking and almost half of them are from Asia.
How long does Nicotine stay in your system?
Once nicotine is inhaled, it is quickly absorbed into the system due to the high blood flow in the lungs. It only takes around ten seconds to reach the brain. Nicotine is metabolized in the liver and further breakdown occurs in the lungs and the kidneys.
The main metabolites produced are nicotine N-oxide and cotinine (major indicator of nicotine presence). Generally, it takes about 72 hours from the last use for other nicotine by-products to leave the system. Yet cotinine remains in the system for as long as four days. Cotinine can also remain for several months, depending on how much tobacco was smoked and the length of time the user has smoked.
How long does Nicotine stay in your blood?
The length of time nicotine remains in the blood stream depends on the amount consumed and the frequency of consumption. Nicotine can stay for 48 hours. Beyond this time it is not detected either in the blood or urine. However, the cotinine metabolite can leave traces for about 7 days. There are some people who have anomalies in their genes that trigger the slow metabolism of cotinine. They need to stop smoking for at least a day or more to clear the nicotine metabolites from their system. Cotinine levels must be less than 10 ng/ml for an person to pass the blood tests. This is just one part of the answer to the question, “How Long Does Nicotine Stay in Your System?”
How long does Nicotine stay in your urine?
The length of time it takes for nicotine and its metabolites to stay detectable in urine depends on the user’s rate of metabolism, height, weight and the how much water is consumed in a day. On average, nicotine can be detected in the urine for as long as three days. Passive smokers have nicotine traces for about fifteen to twenty days.
How long does Nicotine stay in your saliva?
Most of the nicotine will be excreted from the system within twenty minutes after smoking. Nonetheless, it can be detected in the saliva for approximately 24 hours after the last smoke. Its metabolite, cotinine, can be detected for as long as 4 to 7 days depending on the amount of nicotine consumed. For heavy smokers, it may be detected up to seven to fourteen days. You are beginning to see how challenging it is to adequately answer the question of How Long does Nicotine Stay In Your System.
Once nicotine is absorbed, it will stimulate the adrenal glands. This causes the adrenal glads to secrete epinephrine or adrenaline. The sudden increase of this hormone is likely to promote glycogenolysis as well as tachycardia, tachypnea (rapid breathing) and blood pressure increase.
Moreover, nicotine inhibits insulin release causing slight hyperglycemia and appetite suppression. Nicotine can act as a stimulant and enhance the activity of the brain, improving concentration, memory and cognitive processes.
Dopamine release is enhanced and it causes pleasurable sensations and a calming effect in most smokers.
However, unlike other substances, nicotine has a dual effect on the body. It will function as a stimulant or a sedative depending upon how it is consumed. A stimulating effect is achieved if the smoker draws in short, brisk puffs which produce low blood levels of nicotine and stimulates the release of dopamine and norepinephrine. On the other hand, slow deep puffs increase the level of nicotine in the blood and reduce the transfer of nerve impulses causing a sedating and calming effect due to the release of serotonin.
Studies have shown that women are more prone to develop cancer if they smoke. Moreover, women smokers may experience early menopause compared to those who don’t smoke. This is because nicotine alters the amount of circulating estrogen. If these women are taking oral contraceptives, chances of developing cerebrovascular and cardiovascular diseases are increased. 
Regardless of the risk linked with cigarette smoking, people all over the world are continue to smoke. Many attempt to quit but most of them are unsuccessful. Nicotine is as addictive as cocaine or heroin.
Nicotine has neurophysiologic action on the reward center of the brain or the mesolimbic dopamine system, particularly at the nucleus accumbens (dopamine-rich section). Aside from dopamine, endorphins and corticosteroids are also released which reduces fatigue. It also affect the user’s cognitive processing and results in the desire to repeat the experience over and over again, hence becoming an addiction.
Addiction to nicotine is actually a physical dependence. When a smoker stops smoking, “nicotine craving” is brought about. Individuals react in different ways when nicotine is withdrawn from the system, it may be severe. This is the reason why most smokers have a hard time quitting.
Nicotine Drug Test
Urinal Drug Test
There are economical drug test strips that can detect cotinine in the urine through immunoassay. These inexpensive strips are not very sensitive and could only detect 200 ng/ml cotinine levels within two to five days. More precise urine tests are available through GC-MS that can detect cotinine levels of 5 ng/ml. In addition, “Ion Pair Reversed-Phase Chromatography” has a detection cut-off of 200 ng/ml. Both tests have longer detection time, from seven to ten days. However both tests are more expensive and the time required to obtain the tests is longer.
Nicotine Hair Test
Hair tests can detect both nicotine and its metabolite, cotinine, through GC-MS. The detection cut-off for this procedure is approximately 2 ng/ml nicotine. This test determines the amount of drug molecules that were permanently trapped inside the hair follicles. The standard test can cover at least 90 days from last nicotine use.
Blood Test for Nicotine
Nicotine presence can be detected in the blood for a short period only (about 48 hours) . However, its metabolite, cotinine, can be detected up to about three weeks from the last use and the cut-off detection levels is 200 ng/ml. The amount of nicotine and the length of nicotine use does affect the detection time of nicotine in the bloodstream.
If you are a serious smoker, you can easily see how it is a health hazard. There is help for you to quit. There are many ways your body can be tested for the presence of nicotine. As you see, the issue of how long does nicotine stay in your system is not a simple one. Yet, there are many physicians and researchers and social workers who are interested in finding the best answers and in helping you to quit smoking so you will have better health. You will also be less likely to harm your children with second hand smoke, too.