Tobacco use disorder !

Dependence on nicotine from cigarettes or other tobacco products. It is the leading preventable cause of death; counselling and medicines help people quit.

Updated 2026-11-01

Structures involved

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Why it happens

What it is

A substance use disorder in which nicotine dependence keeps a person using tobacco (cigarettes, cigars, chewed tobacco, hookah) or nicotine products (electronic cigarettes) despite harm. Nicotine causes the dependence; the smoke and other toxins cause most of the disease. Cessation is the single most effective intervention to lower cardiovascular, respiratory and cancer risk.

Who gets it

Tobacco kills more than 8 million people a year worldwide: about 7 million through direct use and more than a million non-smokers exposed to second-hand smoke. In Colombia smoking prevalence has fallen with smoke-free laws, advertising bans and taxes, but use of e-cigarettes and vapes among adolescents is a growing concern. Most adult smokers began before age 18.

Causes

Nicotine, a highly addictive alkaloid that acts on nicotinic receptors
Conditioning: smoking linked to routines, alcohol, coffee and stress
Genetic factors that influence nicotine metabolism and dependence
Social and commercial factors: advertising, availability and smoking by family and peers

Risk factors

Starting in adolescence
Parents or friends who smoke
Mental illness (schizophrenia, depression) and other substance use
Low income and educational level
Use of flavoured or electronic nicotine products

Pathophysiology

Inhaled nicotine reaches the brain in seconds and binds α4β2 nicotinic acetylcholine receptors on dopamine neurons of the ventral tegmental area (midbrain), releasing dopamine in the reward pathway. With repeated exposure receptors desensitise and increase in number, so falling nicotine levels between cigarettes cause craving and withdrawal. In the body, tobacco smoke causes endothelial damage, atherosclerosis and thrombosis, chronic airway inflammation and destruction of alveoli (COPD), and DNA damage from carcinogens.

Classification

Severity by DSM-5 criteria: mild, moderate or severe
Degree of dependence by the Fagerström test (time to first cigarette, number per day)
Tobacco withdrawal (irritability, anxiety, poor concentration, increased appetite, insomnia, craving)

Symptoms and signs

Smoking more or longer than intended and failed attempts to quit
Strong craving and first cigarette soon after waking
Withdrawal within hours of stopping: irritability, anxiety, restlessness, low mood, poor concentration, hunger and weight gain
Cough, sputum and shortness of breath
Yellow-stained fingers and teeth, bad breath and reduced sense of smell and taste
Continuing despite tobacco-related disease (for example angina or COPD)

Diagnosis

Clinical: Ask every patient about tobacco use at every visit and document it (the '5 A' model: ask, advise, assess, assist, arrange follow-up). Quantify pack-years (packs per day × years of smoking) to estimate risk and decide on lung cancer screening.
Tests: Usually not needed. Expired carbon monoxide or cotinine can confirm use or abstinence. Spirometry for chronic cough or dyspnoea; lipids, glucose and blood pressure for cardiovascular risk.
Imaging: Low-dose chest CT for lung cancer screening in eligible older adults with heavy smoking history, according to local guidelines; chest X-ray for respiratory symptoms; abdominal ultrasound in older men who have smoked (abdominal aortic aneurysm screening).

Differential diagnosis

Normal non-dependent occasional use
Other substance withdrawal (alcohol, cannabis) explaining irritability or insomnia
Anxiety or depressive disorder with symptoms similar to withdrawal

Goal of treatment

Complete and lasting cessation of all tobacco and nicotine products, with management of withdrawal and prevention of relapse.

Treatment

Conservative: Brief advice from every health worker plus behavioural counselling (individual, group or by phone or app); combining counselling and medication gives the best results
Medical: Nicotine replacement therapy (patches with short-acting forms such as gum or lozenges), safe for most patients, including those with stable heart disease
Medical: Varenicline, a partial agonist of the α4β2 nicotinic receptor, among the most effective single treatments
Medical: Bupropion, an antidepressant that reduces craving; contraindicated in seizure disorders and eating disorders
Lifestyle: Lifestyle support: set a quit date, avoid triggers such as alcohol, physical activity and smoke-free home
Follow-up: Follow-up and relapse prevention, with monitoring for mood changes and weight gain

Drugs for this condition

Complications

COPD and frequent respiratory infections
Lung, head and neck, oesophageal, pancreatic, bladder, kidney and cervical cancers
Coronary heart disease, stroke, peripheral artery disease and abdominal aortic aneurysm
Low birth weight, preterm birth and sudden infant death with smoking in pregnancy
Osteoporosis, erectile dysfunction, delayed wound healing and poorer surgical outcomes

Prognosis

Most smokers need several attempts to quit. Benefits begin within weeks (better circulation and lung function) and coronary risk falls by about half after one year; quitting at any age adds years of life.

Prevention

Measures of the WHO Framework Convention on Tobacco Control: taxes, smoke-free places, advertising bans and health warnings
Protecting adolescents from e-cigarettes and flavoured products

Test yourself

Think of the answer, then tap the question to see it.

Which receptor is the target of varenicline?

The α4β2 nicotinic acetylcholine receptor (partial agonist).

Which smoking-cessation drug is contraindicated in a patient with a seizure disorder or bulimia?

Bupropion, because it lowers the seizure threshold.

How are pack-years calculated?

Packs smoked per day multiplied by the number of years of smoking.

What combination gives the highest quit rates?

Behavioural counselling plus medication (such as combination nicotine replacement or varenicline).

Add to my cards (4)

Educational information, not medical advice. For any symptom, see a health professional.

Sources: Tobacco and nicotine (World Health Organization (WHO), 2025); Nicotine and tobacco (MedlinePlus (U.S. National Library of Medicine), 2025).

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Representative model, for educational purposes only.

Frontal lobe highlighted on the Durgical 3D model