Nicotine is found in plants from the nightshade family like tobacco, eggplant, potatoes, red peppers, and tomatoes. Nicotiana tabacum is the cultivated tobacco plant that contains nicotine.
Nicotine itself is not a cancer-causing substance nor is it significantly harmful on its own, but it does have attributes that result in a high potential for the development of physical dependence if it is taken in large quantities over time.
Because of this high potential to induce physical dependence (tolerance and withdrawal), nicotine enhances the harmful effects of tobacco products that contain other substances that are potentially toxic.
According to the Centers for Disease Control and Prevention (CDC):
Tobacco is indigenous to America, and it has been used medicinally for centuries.
Tobacco use in Europe and Asia probably resulted as a consequence of early explorers like Columbus bringing tobacco products back to Europe from the Americas. It is believed that tobacco was introduced to Japan by Portuguese sailors, and it was introduced in the Middle East around the 16th century.
Dr. Wilhelm Heinrich Posselt and chemist Karl Ludwig Reimann were able to isolate and identify nicotine in the tobacco plant in the early 1800s. These investigators labeled the substance as toxic.
By the late 1800s, the harmful effects of tobacco products had been recognized by many states. Laws were passed in many of these states to prohibit the sale of nicotine-containing products to minors.
The link between lung cancer, heart disease, and cigarette smoking was not firmly established until 1964. The Food and Drug Administration (FDA) was not given the authority to regulate the advertising or production of tobacco products until 2009.
Nicotine rapidly enters your bloodstream after you inhale the smoke from tobacco. It is able to cross the blood-brain barrier, a protective barrier that is designed to protect your brain from toxins.
Nicotine reaches your brain very rapidly (within seconds) after you smoke. It has a relatively short half-life of about two hours in most cases.
How much nicotine is delivered to your brain depends on several factors:
If you snort tobacco, chew tobacco, or place tobacco snuff inside your mouth, you will more likely get larger quantities of nicotine in your body than when smoking.
About 80 percent of the nicotine you ingest is metabolized by the liver, and it is eliminated mostly through urine. Nicotine metabolites can also be found in hair and saliva.
Nicotine has an interesting range of effects on the body, including both stimulant and sedative effects.
For the most part, the stimulant effects occur due to an increase of adrenaline released in the body through the adrenal glands and a rise in the level of glucose that stimulates blood pressure, heart rate, and respiration. This increase in glucose results from nicotine inhibiting the pancreas from producing insulin.
Nicotine affects neurotransmitters, particularly the neurotransmitter dopamine, as result of its rewarding effects of stimulation, motivation, and increased feelings of pleasure.
The increase in dopamine as a result of using nicotine increases the likelihood that you may try or use nicotine again. Dopamine increases occur with numerous drugs of abuse, including alcohol, opioids, and stimulants like cocaine and methamphetamine.
Other neurotransmitters are also affected, including norepinephrine and acetylcholine.
Sedative effects may occur in individuals who are anxious or nervous as a result of the above mechanism of action of nicotine, particularly as a result of the release of dopamine and other neurotransmitters.
Because nicotine can have stimulating effects by increasing the neurotransmitters dopamine, norepinephrine, and acetylcholine in the body, it can also improve your attention span, concentration, and even memory when taken in small amounts.
Nicotine can result in arousal and increased wakefulness. It may be used to reduce sleepiness in some individuals.
When you start taking nicotine, the substance triggers an increase in numerous neurotransmitters and other hormones in your body. It also offsets the release of insulin and other hormones. This results in a state of imbalance in the homeostatic level of your bodily functions (the steady state that your body tries to maintain).
In an effort to restore balance, your system will automatically start producing neurotransmitters, hormones, and other substances that offset the effects of the nicotine you have ingested. If you keep using nicotine products on a regular basis, your system will reset itself, and substances that your system has produced will be at higher resting levels. You will need to use more nicotine over time to get the same effect you once got from a smaller amount because your system is trying to offset the actions of the drug.
The cycle will continue as long as you use nicotine. As a result, you will develop significant tolerance to the drug.
After your system has continuously reset itself in order to offset the nicotine you have been using, you will again be in a state of imbalance once the nicotine leaves your body. Now, the state of imbalance represents an increase in the level of the substances that were designed to offset the effects of nicotine. As a result, when you are not using nicotine, you may begin to experience withdrawal symptoms, which are often sensations that are the opposite of what nicotine produces.
Withdrawal from nicotine is generally not as severe as withdrawal from drugs like heroin or alcohol, but there is a documented withdrawal syndrome associated with physical dependence on nicotine. According to the American Psychiatric Association (APA), the diagnosable symptoms that occur during withdrawal from tobacco products include the following:
Notice that most of these symptoms are opposite to the effects nicotine produces in most people.
APA lists the symptoms that can occur as a result of the problematic use and abuse of tobacco products in the section on substance use disorders (substance abuse and addictions) in its Diagnostic and Statistical Manual of Mental Disorders – Fifth Edition. The diagnostic symptoms of this particular substance use disorder are similar to the symptoms of other substance use disorders, like alcohol use disorders, opioid use disorders, and even stimulant use disorders.
Physical dependence on nicotine (tolerance and withdrawal) can be a symptom of tobacco use disorder, but only if it occurs in conjunction with significant distress or impairment in functioning due to tobacco use.
Common symptoms associated with tobacco use disorders include:
Because tobacco products are readily available to adults in the United States and there is a significant potential for nicotine to trigger physical dependence, there are a large number of individuals who qualify for a diagnosis of a tobacco use disorder. APA estimates that the prevalence of nicotine dependence in the United States is around 13 to 14 percent in any given year.
According to the American Heart Association, nicotine (especially nicotine that is consumed in tobacco products) is at least as addictive as heroin.
Reducing the amount of nicotine in cigarettes appears to be associated with a decrease in the addictive potential of cigarettes.
Consuming nicotine with other substances like cocaine may enhance the potential to develop a substance use disorder to the other substance.
Nicotine use is associated with side effects that occur in numerous organ systems. These include:
As mentioned above, nicotine is not the primary cancer-causing agent in tobacco products. Compared to some of the other products that are in tobacco products like cigarettes, nicotine is relatively harmless.
The additives in cigarettes can actually increase the addictive potential of tobacco products by having an effect on the nicotine in them. These additives are often very dangerous products that produce significant health problems. For instance:
Remember that nicotine is not classified as a carcinogen. Using liquid nicotine is a safer alternative to cigarette smoking or the use of other tobacco products.
Vaping devices or e-cigarettes atomize liquid nicotine by applying heat but without the oxidative effects that occur with burning nicotine. However, the nicotine in these products is still highly addictive and does have some of the side effects listed above. This means that these products are just as potentially addictive, if not more addictive, than tobacco products.
The concoctions used in e-cigarettes and other vaping products are not chemical-free. Different devices, brands, and products may contain dangerous concentrations of nicotine or other chemicals that are potentially carcinogenic, as the research has demonstrated. For instance, diacetyl, a chemical used in some of these products, is associated with respiratory issues.
Thus, there is no reason to think that the use of e-cigarettes is completely safe, nor does their use decrease the addictive potential of nicotine.
Treatment of a tobacco use disorder or physical dependence on nicotine is similar to treatment of any other type of substance use disorder. Medications can be used to address nicotine dependency, and behavioral interventions like therapy can be used to address problems with tobacco use.
As with all other substance use disorders, the risk of relapse is very high. The best approach is comprehensive program that stresses continued abstinence from nicotine and other drugs (including alcohol) that may spur a return to nicotine use.
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