Nicotine: what it is, its characteristics and how it affects our body

The World Health Organization (WHO) estimates that there are more than 1.3 billion tobacco smokers in the world. Beyond this alarming figure, if we go further on the medical level, the thing worsens considerably: up to half of those who consume it eventually die. Lung cancer clearly illustrates this fact, as it is responsible for 25% of neoplastic processes in humans and accounts for more than 130,000 deaths per year.

As far as we all know the harms of this addiction, in some countries smoking remains completely normalized. Without going any further, it is estimated that in regions like Spain, 24.5% of the adult population smokes, with all the psychological, social and physiological effects that this entails.

Beyond the numbers, lung cancer, health and other issues, tobacco is fascinating from a physiological standpoint. Today we tell you all about its key component: nicotine.

    What is nicotine?

    Nicotine, chemically named (S) -3- (1-methylpyrrolidin-2-yl) pyridine, is an alkaloid found mainly in the tobacco plant (Nicotiana tabacum). It is a secondary metabolite produced by the plant from amino acids, which is why it contains nitrogen compounds in its chemical formula. Tobacco is not the only alkaloid known and used by humans: cocaine and caffeine are also examples.

    Nicotine is stored mainly in the leaves of the plant, which accounts for 5% of the total dry weight of the plant. This has a clear biological function: the compound is a pesticide which prevents certain invertebrates from attacking the leaves. In addition to this, it is also attributed with herbicidal properties, which reduces the growth of other plants close to tobacco, resulting in greater availability of resources in the plant.

    In addition to the well-known tobacco plant (Nicotina tabacum), there are other plants that synthesize this alkaloid in varying concentrations. Among them are the following:

    • Some plants that are low in nicotine include horsetail, celery, potato, and even papaya.
    • The tobacco tree (Nicotina glauca) does not contain a lot of nicotine, although it is rich in the alkaloid anabasine, a nicotinic receptor agonist.
    • Mapacho (Nicotina rustica) contains higher amounts of nicotine in the normal tobacco plant. For this reason, ingesting its leaves in excess is considered dangerous.

    As you can see, not only the typical tobacco plant contains nicotine. After all, we are talking about a pesticide and a herbicidal alkaloid that can provide the plant with many benefits when it comes to surviving in the environment.

    A cigarette contains on average 12 milligrams of nicotine, although these values ​​can vary from 8 to 20 milligrams.. Oddly enough, it should be noted that the content of 4 cigarettes (50 mg of nicotine) is able to end the life of a man, if the compound is injected intravenously. Therefore, we are not surprised to learn that there have been several serious poisonings in children from directly ingesting the contents of cigars.

    Nicotine actions on the body

    According to studies, nicotine is a substance with stimulating properties and responsible for addiction to cigarettes. The main human brain structures involved in this dependency mechanism are the nucleus accumbens, the prefrontal cortex, the hippocampus and the amygdala. this alkaloid produces direct (and indirect) actions on neurotransmitters, Such as dopamine, acetylcholine, norepinephrine and serotonin.

    When a low dose of nicotine is given to humans, it is it produces a feeling of instant gratification when endorphins are released in cerebral gratification circuits. As with other drugs, feelings of reward and euphoria positively correlate with the release of the neurotransmitter dopamine, leading to the compulsive urge to reuse the drug.

    In addition to these quantifiable brain effects, nicotine encompasses many other frameworks of action in the human body. Among them are the following:

    • Decreases Appetite: Nicotine helps you lose weight because it interacts with enzymes related to appetite and intake. Many tobacco users gain weight drastically when they stop using it.
    • Increases intestinal activity.
    • It causes the formation of more saliva and phlegm: it is an irritation product of the upper respiratory tract.
    • Increases heart rate and blood pressure.
    • It stimulates memory and arousal: for this reason, chronic smokers feel the need to smoke in order to concentrate and be active.

    After inhaling tobacco smoke, the concentration of nicotine in the blood increases rapidly and, in less than 20 seconds, it reaches the brain and activates the previously described reward mechanisms. As surprising as it may seem, inhaled by tobacco smoke, this alkaloid reaches its destination sooner than if administered intravenously.

    Unfortunately, nicotine works as quickly as it disappears. This alkaloid peaks at 10 seconds, so it produces a short and quick gratification, but sweet in nature. For this reason, a smoker requires the consumption of several cigarettes a day to feel perfectly well and focus their attention on relevant tasks.

    When you stop smoking, that’s when the neurological death occurs: continued smoking causes the secretion of exceptionally low dopamine levels by decreasing nicotine concentrations in the central nervous system. This undoubtedly underlies the dangerous bases of addiction that this substance generates.

      Physical and psychological dependence

      To understand the mechanism of nicotine addiction, it is essential to differentiate the physical from the physiological, although the two fronts are largely interconnected.

      Physical dependence is that which occurs when symptoms appear within a few days / hours of stopping the medication in question. of the patient’s life. Mild clinical signs usually appear 2-3 hours after the last cigarette, peaking within 2-3 days.

      Among them we find headache, tension, anxiety, depression, difficulty concentrating, and the urge to take a cigarette in your mouth. It should be noted that physical dependence is conditioned, in large part, by tolerance: the less the body is sensitive to the substance, the more it needs it.

      On the other hand, psychological addiction refers to the need for pleasure that the substance generates or, if not, how it helps the patient to endure their problems. The two events are largely interconnected, as they cause the same symptoms described above.

      Is it difficult to quit smoking?

      Any reader who has tried (or succeeded) to quit will know how to answer this question forcefully. As shocking as it may sound, the chances of being addicted to tobacco (28%) are higher than cannabis (8%) or cocaine (11%). While other drugs are more clearly harmful in the short term, tobacco kills slowly but continuously.

      Most smokers try to quit on average twice before they quit for good. In addition, 25% of those who offer it are not able to last more than 24 hours without taking a cigarette in their mouth. The degree of addiction is such that more than half of patients who have had lung cancer surgery start smoking again at some point in their lives. In these cases, the addiction clearly outweighs the desire to live.


      Certainly, we are facing one of the most problematic (if not the most important) drugs in society today. The World Health Organization backs this claim with data falling like a vase of cold water: the tobacco kills up to 1 in 2 people who use it.

      For all these reasons, lung cancer is one of the most common malignant tumor processes in the world. Even more worrying, this type of cancer is one of the deadliest, because the patient’s survival rate 5 years after diagnosis does not reach 20%. After reading these lines, there is no doubt that starting to smoke is one of the worst decisions you can make in life.

      Bibliographical references:

      • Is Nicotine Addictive? National Institute of Drug Abuse (NIH). Collected January 29 from
      • Camp, A. (2002). Nicotine addiction: approach to its pharmacological management. Tower. Columbus. Psychiatry, 67-72.
      • Nicotine, Collected January 29 at
      • Nicotine and Tobacco, Retrieved January 29, from
      • Secades Vila, R., and Fernández Hermida, JR (2001). Effective psychological treatments for drug addiction: nicotine, alcohol, cocaine and heroin. Psychotheme, 13 (3).
      • Tobacco, WHO. Collected January 29 at

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