Nicotine is a naturally occurring compound that is found in the tobacco plant and is responsible for addiction to tobacco-containing products. Nicotine is found in tobacco products like cigars, cigarettes, hookah and non-tobacco products like e-cigarettes. Nicotine is a stimulant and is used because of its ability to elevate mood. Prolonged use of nicotine products can lead to dependence and addiction.

What Is Nicotine?

Nicotine is a naturally occurring alkaloid found in the tobacco plant that is used for its stimulating and pleasurable effects. Nicotine is also present in other plants of the nightshade or Solanaceae family and is found in small quantities in eggplant, green bell peppers, tomatoes and potatoes.

The tobacco leaves used in various products like cigarettes contain thousands of chemicals that have more adverse health effects than nicotine. However, nicotine is primarily responsible for the addictive properties of tobacco products.

What Is Nicotine Used For?

Nicotine is used for its euphoric effects and is considered to be as addictive as heroin. Nicotine also reduces stress and anxiety and hence may be used to elevate mood. Nicotine is a stimulant and causes an activation of the sympathetic nervous system, resulting in symptoms of increased arousal, such as increased heart rate and blood pressure.

Nicotine also acutely improves cognitive function involving attention and memory. Long-term use of nicotine results in the development of physical dependence and in such cases, nicotine intake is necessary to function normally. Nicotine is being investigated for its potential in the treatment of schizophrenia, attention-deficit hyperactivity disorder (ADHD) and Alzheimer’s disease due to its positive impact on cognitive function.

What Does Nicotine Look LIke?

Smoking in the form of cigarettes is one of the most common forms of nicotine use. Smoking rapidly elevates the levels of blood nicotine levels and delivers it to the brain where nicotine produces its stimulating and pleasurable effects. Tobacco may also be smoked using cigars, pipes or a water pipe (hookahs).

Besides smoking, nicotine may also be obtained through smokeless tobacco by oral ingestion in the form of chewing tobacco or by sniffing (snuff). Chewing tobacco is held between the cheek or lips and the gum, and nicotine is then absorbed through the tongue and gums. Dry snuff is snorted or sniffed into the nasal cavity.

Although the smoking of cigarettes has waned recently, there has been an upsurge in the use of e-cigarettes. One of the components of the e-cigarette is the cartridge that holds a fluid containing nicotine and flavorings. This fluid is known as e-liquid, e-juice or vape juice. A battery-powered heating element vaporizes the e-liquid to allow the inhalation of the vapor.

Nicotine Side Effects

Nicotine binds to the receptors for the neurotransmitter acetylcholine (nicotinic acetylcholine receptors or nAChRs) that are present in the brain, the peripheral nervous system and skeletal muscles. The binding of nicotine to the nicotine-acetylcholine receptors results in the increased release of dopamine along with other neurotransmitters like serotonin and norepinephrine. The activation of dopaminergic neurons that are involved in the reinforcement of rewarding behaviors is responsible for the addictive properties of nicotine.

Long-term use of nicotine results in changes in multiple brain regions including the reward center (that contains dopamine neurons), that makes nicotine intake necessary for the individual to function normally, causing physical dependence on nicotine. Nicotine also causes an activation of the sympathetic nervous system (involved in fight-or-flight response), resulting in increased arousal characterized by increased heart rate and blood pressure.

Although nicotine itself has adverse effects on physical and mental health, many of the more severe effects typically associated with smoking, such as lung cancer, oral cancer,  cardiovascular diseases, chronic bronchitis and other ailments are due to tobacco smoke and other ingredients in cigarettes.

Even e-cigarettes contain various ingredients besides nicotine that may have negative health consequences by themselves or upon being degraded when vaporized. Nicotine has reinforcing properties and causes individuals to continue smoking despite being aware of the negative consequences of using tobacco products or e-cigarettes. In other words, the long-term use of nicotine products can lead to addiction.

  • Short-Term Effects of Nicotine Use:

    Nicotine is a stimulant that causes an activation of the sympathetic nervous system (involved in the fight-or-flight response) leading to increased arousal. Consistent with this mode of action, the short-term effects of nicotine use include

    • Increase in blood pressure and heart rate
    • Narrowing or constriction of blood vessels
    • Reduced appetite
    • May cause headaches, sweating, nausea and vomiting
    • Decreased body temperature due to the increased rate of breathing

    Nicotine content in e-liquids is unregulated and inadvertent intake of high concentrations of nicotine can lead to poisoning. Some of the effects of nicotine poisoning may include:

    • Seizures
    • Tremors
    • Fainting
    • Confusion
    • Increased breathing rate
    • Respiratory failure
    • Death

  • Long-Term Effects of Nicotine Use:

    Although there is considerable epidemiological data (human studies) that support an association between the use of tobacco products and cancer and cardiovascular diseases, there is limited evidence on the adverse effects of long-term nicotine use.

    Some of the information on the long-term effects of nicotine are based on animal studies or studies conducted based on the exposure of cultured cells to nicotine. The findings of such studies may or may not extend to the effects of nicotine in humans. Some of the long-term effects of nicotine include:

    • Chronic exposure to nicotine is associated with reduced sensitivity of tissues to insulin and may increase the risk of developing type-2 diabetes
    • Because of its cardiovascular effects, chronic use of nicotine can increase the risk of arrhythmias, hypertension and heart attack. Nicotine may also contribute to an increased chance of heart disease by causing thickening of arterial walls (atherosclerosis).
    • Although nicotine does not seem to cause cancer, long-term use of nicotine may stimulate the formation of new blood vessels (angiogenesis). The formation of tumors is accompanied by angiogenesis to support the metabolic needs of the new tissue. Nicotine may thus play an accessory role in the progression of cancer.
    • Nicotine can adversely affect the brain development of adolescents. The human brain continues developing until the age of 25 and intake of nicotine during adolescence and early youth can disrupt normal brain development. Nicotine use during this sensitive period can have lasting effects on the brain. Nicotine intake during adolescence is linked with mood disorders, cognitive (intellectual) impairment involving memory, attention and learning, and impaired impulse control. Chronic exposure to nicotine during adolescence can also lead to an increased risk of dependence on illicit substances like methamphetamine and cocaine
    • Use of tobacco products during pregnancy can expose the fetus to nicotine. Smoking during pregnancy can lead to miscarriages and premature birth. The precise effects of nicotine on the fetus are not known, but animal studies indicate that prenatal nicotine exposure can result in cognitive deficits later in life involving learning, memory and attention.
    • Prolonged use of nicotine can cause addiction to tobacco products or e-cigarettes.

How Long Does Nicotine Stay in Your System?

The half-life of nicotine is approximately two to three hours after consumption. Nicotine is primarily metabolized by the liver into over 20 metabolites that are eliminated via the urine. Cotinine is the primary metabolite of nicotine and is extensively used as a marker for detecting nicotine use. Cotinine has a half-life of 16-20 hours. The length of time that nicotine stays in someone’s system depends on how it’s measured.

  • Nicotine detection times by test type:

    • Blood: Nicotine is detectable in the blood for one to three days, whereas cotinine is detectable for up to ten days.
    • Urine: Detection by measurement of cotinine levels in urine samples is the most common method of detecting nicotine use and is more sensitive than detection from blood samples. Cotinine is detectable up to three to four days after abstinence from nicotine use.
    • Saliva: Measuring cotinine levels in saliva is the most sensitive way of measuring nicotine use. Cotinine also remains detectable in the saliva for three to four days.
    • Hair: Nicotine can be detected in hair follicles for one to three months and may remain detectable for even a year.
    • Breast milk: Breastfeeding mothers are advised not to smoke or use other nicotine products. Nicotine remains in breast milk for three hours following smoking.

Is Nicotine Addictive?

Nicotine is, indeed, addictive and is responsible for the long-term use of cigarettes, despite being aware of the negative consequences of tobacco or nicotine use. Long-term use of nicotine leads to the development of dependence on the substance due to the adaptation of neurons in various brain circuits, including the dopamine neurons in reward centers of the brain. In other words, these adaptations motivate individuals to continue using nicotine and make nicotine use necessary to function normally.

Abstinence from nicotine use results in withdrawal symptoms that involve intense cravings for nicotine, anxiety, depression, increased appetite and problems concentrating. These withdrawal symptoms are severe and unpleasant and often result in relapse, leading individuals to continue nicotine use despite its negative impact on physical health.