Nicotine Addiction, Effects, Toxicity, Poisoning

Nicotine is a highly addictive substance, which when smoked through cigarettes or administered by other means, can result in a substance dependence (nicotine addiction). Nicotine itself has harmful effects in the body but it is the method of administration that is at times more detrimental to one’s health. The health hazards of the most common method of nicotine administration, namely cigarette smoking, is often confused with the effects of nicotine. However many of the harmful effects of cigarette smoking is due to the compounds, other than nicotine, emitted by burning tobacco and inhaling the smoke.

Nicotine addiction is not different from other forms of substance dependence, whether that of narcotic or pharmaceutical drugs. There are temporary feelings of pleasure (‘high’ or ‘upper’) followed by withdrawal symptoms like irritability and agitation (‘downer’) and in the early stages of nicotine use, this prompts the user to administer another dose in order to experience the ‘upper’ again. Once addiction sets in, a user will  often crave a regular dose of the substance in order to allay the ‘downer’ symptoms.

Methods of Nicotine Administration

The routes of administration may differ but the effects of nicotine on the body are the same and once addicted, a user will find it difficult to function effectively without nicotine.


This involves burning dried tobacco leaves available as cigarettes, cigars or pipe tobacco. Apart from nicotine within the smoke, other noxious chemicals like cyanide are also inhaled. The hookah or shisha which is commonly used in Asia has become a popular alternative to cigarette smoking globally. Here the flavored tobacco is ‘bubbled’ through a water ‘filter’ and this is believed to remove some of the noxious chemicals in the smoke. However there is a growing body of evidence to refute such claims. (1, 2) Smoking tobacco puts the user at risk of developing throat and lung cancer as well as chronic obstructive pulmonary disease (COPD).

Chewing and Inhaling

In this method of administration, nicotine is absorbed through the mouth lining by chewing the tobacco or through the nasal lining by sniffing dust-like tobacco particles (snuff). Chewing or inhaling tobacco increases the risk of developing mouth cancer and nasal polyps.

Electronic Cigarettes

The electronic cigarette or e-cigarette uses liquid nicotine which is heated into a vapor and inhaled upon drawing on the device. This system delivers nicotine into the system without the noxious chemicals produced by burning tobacco. While the electronic cigarette has been touted as the safer option for nicotine use, the user is still at risk of the harmful effects of nicotine itself. Since the e-cigarette is a fairly new nicotine administration method, all the possible dangers associated with this device has not as yet been established.

Nicotine Replacement

A number of products have been developed for temporarily administrating nicotine in a user who is attempting to overcome their addiction. These methods include the transdermal patch, chewing gum nasal spray, inhaler and lozenges. These replacement products are short term measures for reducing the severity of nicotine withdrawal symptoms. They are sometimes used by certain users to supplement their nicotine intake in situations where other administration methods like smoking a cigarette or chewing tobacco is not socially acceptable.

Effects of Nicotine

Whether nicotine is inhaled, chewed or administered in any other way, it is absorbed into the blood stream and quickly reaches the brain, where it exerts its actions on the cholinergic receptors. By increasing the level of dopamine in the ‘reward circuits’ of the brain, nicotine produces its pleasurable symptoms which ultimately lead to nicotine addiction. By stimulating the release of neurotransmitters such as acetylcholine, epinephrine, dopamine and beta-endorphin, nicotine causes central nervous system stimulation as well as relaxation.

The effects of nicotine are short-lived and quickly followed by withdrawal symptoms. Craving for another ‘high’ and avoiding the nicotine withdrawal symptoms motivates the user to administer another dose once the effects wear off. With time, there is a decreased sensitivity of the cholinergic receptors to the effects of nicotine and larger quantities of nicotine are needed to produce the same pleasurable effects. This is referred to as tolerance and it is one of the reasons why smokers gradually increase the number of cigarettes they smoke in a day.

Due to the increased epinephrine (adrenaline) secretion, there is an increase in heart rate, blood pressure and respiration. An enhanced sense of well-being is produced along with increased alertness and concentration level. By suppressing insulin secretion from the pancreas and enhancing glucose release, nicotine can also produce high blood sugar level in smokers.

Anxiety and depression are common in nicotine addicts and it is often aggravated during the withdrawal period. The absence of nicotine in the body triggers intense craving and is one of the most difficult symptoms to contend with. These cravings can persist for months after discontinuing the use of nicotine.

Nicotine Toxicity, Poisoning

High doses of nicotine can produce toxic symptoms such as nausea, vomiting, diarrhea, excessive salivation, headache, dizziness, abdominal pain, agitation, tremors, convulsions and breathing difficulty. Death due to the administration of extremely high doses of nicotine may occur as a result of respiratory failure or due to other pre-existing medical conditions that are aggravated by the sudden administration of large doses of nicotine.

Most cases of nicotine poisoning are unintentional or accidental and usually involves the consumption of products containing high quantities of nicotine, like insecticides. The simultaneous use of nicotine replacement products along with tobacco smoking, chewing or sniffing may also result in nicotine poisoning.

Induced vomiting, gastric lavage (to wash out the stomach) and using activated charcoal (to bind the nicotine in the stomach thereby preventing its absorption into the bloodstream) are the methods used to treat nicotine poisoning. Respiratory and cardiovascular support may become necessary in these cases.


  1. Is hookah smoking safer than smoking cigarettes? Richard D. Hurt, M.D.; Mayo Clinic.
  2. Waterpipe Tobacco Smoking. World Health Organization (WHO) Study Group on Tobacco Product Regulation.

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