Tobacco use remains the leading preventable cause of death in the United States and a major driver of cardiovascular, pulmonary, and oncologic morbidity, with disproportionate prevalence among patients with psychiatric and other substance use disorders.^[1-2] DSM-5-TR classifies tobacco-related disorders under Substance-Related and Addictive Disorders, with two principal entities: Tobacco Use Disorder and Nicotine Withdrawal, plus tobacco-induced sleep disorder.^[3] Nicotine acts as a potent agonist at nAChRs — particularly the α4β2 subtype — driving mesolimbic dopamine release and rapid neuroadaptation that underlies tolerance, withdrawal, and craving.^[4] First-line pharmacotherapy is varenicline 0.5 mg PO QD titrated to 1 mg BID, combination NRT (long-acting patch plus short-acting gum or lozenge), or bupropion 150 mg PO QD titrated to 150 mg BID, each paired with behavioral counseling.^[5-6] Bottom line: every clinical encounter is an opportunity to screen, advise, and offer treatment — combination pharmacotherapy plus counseling roughly doubles long-term abstinence over either alone.^[5]

Tobacco use is the single largest preventable cause of disease and premature death globally and in the United States.^[1-2] Despite decades of decline, prevalence remains high in specific populations, with steep gradients by socioeconomic status, mental illness, and other substance use.

Prevalence and burden

• Approximately 11.5% of US adults currently smoke cigarettes; tobacco use causes roughly 480,000 US deaths annually, including from secondhand smoke.^[2]
• Worldwide, tobacco kills more than 8 million people per year, including approximately 1.3 million from secondhand smoke exposure.^[1]
• Lifetime prevalence of DSM-5 tobacco use disorder among current US adult smokers is high, with moderate-to-severe forms in the majority of daily smokers.^[7]

Sociodemographic patterns

• Onset of regular use typically occurs in adolescence; nearly 90% of adult daily smokers had their first cigarette before age 18.^[2]
• Higher prevalence is observed among males, individuals with lower educational attainment and income, American Indian/Alaska Native populations, and LGBTQ+ adults.^[2]
• Electronic cigarette (e-cigarette, vaping) use has risen sharply among adolescents and young adults; nicotine dependence develops with these products as well.^[2]

Psychiatric comorbidity

• Smoking prevalence is two to four times higher among persons with schizophrenia, bipolar disorder, major depressive disorder, and other substance use disorders compared with the general population.^[8]
• Patients with serious mental illness consume an estimated 30-40% of cigarettes sold in the United States and die on average 10-25 years earlier than peers, with tobacco-related illness a leading cause.^[8]
• Co-use with alcohol and cannabis is common and worsens prognosis for both disorders.^[8]

Nicotine is a fast-acting, highly reinforcing alkaloid whose pharmacokinetics and central neuropharmacology explain both rapid dependence and protracted withdrawal.^[4] Tobacco use disorder is a chronic, relapsing brain disease shaped by genes, development, and environment.^[1]

Pharmacology

• Inhaled nicotine reaches the brain within 10-20 seconds and binds nicotinic acetylcholine receptors, with the α4β2 subtype most relevant to reinforcement.^[4]
• Receptor activation in the ventral tegmental area triggers dopamine release in the nucleus accumbens — the final common pathway for addictive reinforcement.^[4]
• Chronic exposure produces receptor upregulation and desensitization; abstinence unmasks hypofunction, producing withdrawal symptoms and craving.^[4]

Neurocircuitry

• Reinforcement involves the mesocorticolimbic dopamine system; habit and compulsive use engage dorsal striatum; cue reactivity engages amygdala and insula; relapse engages prefrontal-striatal control circuits.^[9]
• Insular cortex damage has been associated with disrupted smoking urges in case reports, supporting its role in interoceptive craving.^[9]

Genetics

• Heritability of nicotine dependence is estimated at 40-75% across twin studies.^[10]
• Variants in the CHRNA5-A3-B4 nicotinic receptor gene cluster on chromosome 15q25, including the rs16969968 variant, are associated with heavier smoking and lung cancer risk.^[10]
• CYP2A6 polymorphisms alter nicotine metabolism; slow metabolizers smoke fewer cigarettes and respond differently to NRT and varenicline.^[10]

Developmental and environmental factors

• Adolescent exposure is associated with long-lasting changes in reward and executive circuits and a higher likelihood of lifetime dependence.^[2]
• Peer use, parental smoking, tobacco marketing exposure, and lower socioeconomic status increase initiation risk.^[2]

DSM-5-TR classifies tobacco-related disorders under Substance-Related and Addictive Disorders. The two clinically central entities are tobacco use disorder and nicotine withdrawal; tobacco-induced sleep disorder is also listed.^[3]

Tobacco use disorder

• Defined by a problematic pattern of tobacco use leading to clinically significant impairment or distress, with at least 2 of 11 criteria within a 12-month period.^[3]
• Criteria mirror the general substance use disorder framework and include impaired control (using more or longer than intended; persistent desire or unsuccessful efforts to cut down; time spent obtaining or using; craving), social impairment (failure to fulfill role obligations; continued use despite interpersonal problems; activities given up), risky use (use in physically hazardous situations; continued use despite known physical or psychological problems), and pharmacologic criteria (tolerance; withdrawal).^[3]
• Severity: mild (2-3 criteria), moderate (4-5), severe (6 or more).^[3]
• Specifiers: in early remission, in sustained remission, on maintenance therapy (for those on agonist medications such as NRT or varenicline), and in a controlled environment.^[3]

Nicotine withdrawal

• Requires daily use of tobacco for at least several weeks, abrupt cessation or reduction, and the development within 24 hours of at least 4 of 7 symptoms: irritability/frustration/anger; anxiety; difficulty concentrating; increased appetite; restlessness; depressed mood; insomnia.^[3]
• Symptoms cause clinically significant distress or impairment and are not better explained by another medical or mental disorder.^[3]
• Peak severity is typically within the first week and most physical symptoms resolve within 2-4 weeks, although craving and dysphoria can persist for months.^[4]

ICD-11 considerations

• ICD-11 includes nicotine dependence within "Disorders due to use of nicotine," with categories for harmful use, dependence, intoxication, and withdrawal; criteria are conceptually similar but use a three-feature dependence definition rather than the 11-criterion DSM count.^[11]

Most patients with tobacco use disorder report wanting to quit and have made prior attempts; the clinical picture is dominated by entrenched daily use, craving, and predictable withdrawal on abstinence.^[5] Recognition is straightforward; the harder task is sustained engagement in treatment.

Typical presentation

• Daily smoking, often initiated in adolescence, with progressive escalation to a stable daily quantity (commonly 10-25 cigarettes/day).^[2]
• First cigarette within 30 minutes of waking and high cigarettes-per-day count are markers of greater dependence on the Fagerstrom Test for Nicotine Dependence.^[12]
• Multiple prior quit attempts are the rule; on average it takes 6-30 attempts before sustained abstinence.^[5]

Withdrawal course

• Craving and irritability begin within hours; appetite increase, insomnia, and depressed mood develop over days.^[3]
• Weight gain averages 4-5 kg in the year after quitting and is greater in women and heavy smokers; concerns about weight are a common relapse trigger.^[5]
• Cue-induced craving (after meals, with alcohol, with stress) can persist for months and is a leading mechanism of late relapse.^[9]

Health consequences

• Cardiovascular: ischemic heart disease, stroke, peripheral arterial disease, abdominal aortic aneurysm.^[2]
• Pulmonary: chronic obstructive pulmonary disease, recurrent respiratory infection, impaired lung function.^[2]
• Oncologic: lung, head and neck, esophageal, gastric, pancreatic, bladder, cervical, and other cancers.^[2]
• Reproductive and perinatal: infertility, ectopic pregnancy, fetal growth restriction, preterm birth, sudden infant death syndrome.^[2]

Quitting before age 40 reduces tobacco-related mortality by approximately 90%.^[13]

The diagnosis of tobacco use disorder is usually unambiguous in a daily smoker meeting DSM-5-TR criteria. The differential matters mostly for distinguishing withdrawal symptoms from primary psychiatric disorders and for assessing co-use of other nicotine-containing products.^[3]

Key entities to distinguish

• Other nicotine-product use: e-cigarettes (vaping), smokeless tobacco, hookah, and pipe tobacco can each produce dependence; document product type and quantity, as pharmacotherapy strategy is similar but baseline nicotine intake varies.^[2]
• Major depressive disorder: depressed mood during nicotine withdrawal can mimic MDD; symptoms attributable solely to withdrawal typically remit within 2-4 weeks of abstinence, whereas MDD persists.^[3]
• Generalized anxiety disorder: withdrawal-related anxiety also remits with sustained abstinence; pre-existing GAD persists and may require independent treatment.^[3]
• Adult ADHD: poor concentration during withdrawal can resemble ADHD; assess longitudinal history of inattention from childhood before diagnosing.^[3]
• Caffeine intoxication or withdrawal: shares irritability, restlessness, and headache; quantify caffeine intake.^[3]
• Medical mimics of withdrawal symptoms: hyperthyroidism, hypoglycemia, and anemia can present with irritability, restlessness, and concentration problems and are worth screening when symptoms are atypical or persistent.^[14]

Every clinical encounter is an opportunity to identify, advise, and treat tobacco use. The US Preventive Services Task Force gives behavioral and pharmacologic interventions for adult smokers a grade A recommendation.^[15] The widely used 5 A's framework structures the brief intervention.^[5]

5 A's framework:

• Ask: screen every patient at every visit for tobacco and nicotine-product use.^[5]
• Advise: give a clear, personalized recommendation to quit.^[5]
• Assess: gauge readiness to make a quit attempt within the next 30 days.^[5]
• Assist: offer behavioral counseling and pharmacotherapy; set a quit date.^[5]
• Arrange: schedule follow-up, ideally within the first week after the quit date.^[5]

History elements

• Product(s) used, daily quantity, duration of use, time-to-first-cigarette after waking, prior quit attempts and methods, longest abstinence, triggers for relapse.^[5]
• Co-use of alcohol, cannabis, and other substances; psychiatric history including depression, anxiety, psychosis, ADHD, and prior response to bupropion or varenicline.^[5]
• Medical history: cardiovascular disease, COPD, pregnancy, seizure disorder, eating disorder (relevant to bupropion contraindications).^[6]

Validated instruments

• Fagerstrom Test for Nicotine Dependence (FTND) and its shorter Heaviness of Smoking Index quantify physical dependence and predict withdrawal severity and treatment response.^[12]
• Minnesota Nicotine Withdrawal Scale rates withdrawal symptom severity over time.^[16]
• Brief readiness-to-change assessments and the Patient Health Questionnaire-9 are useful adjuncts in primary care and psychiatric settings.^[5]

Objective measures

• Exhaled carbon monoxide gives an immediate, motivating biomarker of recent smoking and is useful in research and specialty clinics.^[5]
• Cotinine (urine, saliva, or plasma) confirms recent nicotine exposure with a half-life of approximately 16 hours and distinguishes smokers from non-smokers and from NRT users only when nicotine-specific metabolites are measured.^[5]

What not to order

• Routine neuroimaging, electroencephalography, or extensive endocrine workup is not indicated in uncomplicated tobacco use disorder.^[5]

Combining pharmacotherapy with behavioral support produces the highest long-term abstinence rates and is recommended for all adults willing to make a quit attempt; pharmacotherapy alone or counseling alone are each superior to no treatment.^[5-6] Three first-line agents have strong evidence: varenicline, combination NRT, and bupropion SR.^[5-6]

Pharmacotherapy

• Varenicline is a partial α4β2 nicotinic agonist; standard dosing is varenicline 0.5 mg PO QD for days 1-3, 0.5 mg BID for days 4-7, then 1 mg BID for 12 weeks, with an additional 12 weeks of maintenance to reduce relapse.^[6]
• Network meta-analyses suggest varenicline is the most effective single agent for continuous abstinence at 6 months, with effect sizes comparable to combination NRT.^[17]
• Combination NRT pairs a long-acting nicotine patch (21 mg/24 h for >10 cigarettes/day, tapering over 8-12 weeks) with a short-acting form (gum, lozenge, inhaler, or nasal spray) used PRN for craving; combination outperforms monotherapy NRT.^[5-6]
• bupropion 150 mg PO QD for 3 days, then 150 mg BID, started 1-2 weeks before the quit date and continued for 7-12 weeks, with optional extension; bupropion approximately doubles long-term quit rates versus placebo.^[6,18]
• Combining varenicline with NRT is supported by evidence in heavier smokers, though the magnitude of added benefit varies across trials.^[17]
• Second-line agents (where first-line is contraindicated or has failed) include nortriptyline and clonidine; both have evidence of efficacy but more adverse effects and are not FDA-approved for this indication.^[5,18]
• Cytisine, a plant-derived partial nicotinic agonist used widely in Eastern Europe, has evidence of efficacy comparable to NRT and possibly approaching varenicline; not currently FDA-approved.^[19]

Special considerations for pharmacotherapy

• The EAGLES trial found no significant increase in moderate-to-severe neuropsychiatric adverse events with varenicline or bupropion compared with NRT or placebo, including among patients with stable psychiatric disorders; the FDA removed the boxed warning for varenicline in 2016 on this basis.^[20]
• Bupropion is contraindicated in seizure disorder, current or prior anorexia nervosa or bulimia nervosa, and concurrent use of monoamine oxidase inhibitors or abrupt sedative withdrawal.^[6]
• NRT is safe in stable cardiovascular disease, including in the weeks after acute coronary syndrome, when continued smoking carries greater risk than nicotine replacement.^[5]

Psychotherapy

• Brief clinician counseling (3-10 minutes) increases quit rates; intensive counseling (more than 10 minutes, multiple sessions) is more effective and has a dose-response relationship with abstinence.^[5]
• Cognitive-behavioral therapy targets cue identification, coping skills, and relapse prevention; group and individual formats are both effective.^[5]
• Motivational interviewing is useful for patients not yet ready to quit and increases the probability of a future quit attempt.^[5]
• Telephone quitlines (in the US, 1-800-QUIT-NOW), text-message programs (SmokefreeTXT), and web-based interventions are evidence-based and broadly accessible.^[5]
• Contingency management — financial incentives contingent on biochemically verified abstinence — increases abstinence during the intervention; durability after withdrawal of incentives is more variable.^[21]

Neuromodulation

• Repetitive transcranial magnetic stimulation targeting the lateral prefrontal cortex and insula received FDA clearance for short-term smoking cessation in 2020 based on a multicenter sham-controlled trial; access is limited and it is typically reserved for treatment-resistant cases.^[22]

Adjunctive

• Treat comorbid depression, anxiety, ADHD, and other substance use disorders; untreated comorbidity reduces cessation success.^[8]
• E-cigarettes have evidence as a cessation aid in some randomized trials, with greater 6-12-month abstinence than NRT in select populations; harm reduction is offset by uncertain long-term safety, continued nicotine dependence, and high rates of dual use.^[23]
• Acupuncture, hypnosis, and laser therapy have not shown consistent efficacy beyond placebo and are not recommended as primary treatment.^[5]

Tobacco cessation pharmacotherapies are generally safe and well tolerated; most adverse effects are mild and self-limited. The greater clinical risk lies in undertreatment.^[5-6]

Common adverse effects

• Varenicline: nausea (most common, dose-related), abnormal or vivid dreams, insomnia, headache, constipation; nausea improves with food and slow titration.^[6]
• NRT: skin irritation under the patch, mouth and throat irritation with gum or lozenge, hiccups, dyspepsia.^[5]
• Bupropion: insomnia, dry mouth, headache, agitation; dose-dependent risk of seizure (approximately 0.1% at 300 mg/day with immediate-release formulation, lower with SR).^[6]

Serious or rare adverse effects

• Bupropion seizures, especially at doses above 450 mg/day, with abrupt discontinuation of alcohol or sedatives, or in patients with predisposing factors.^[6]
• Cardiovascular events with varenicline have been debated; pooled analyses and EAGLES do not show clinically meaningful excess risk, and the agent is recommended in stable cardiovascular disease.^[20]
• Suicidal ideation and behavior were the basis of historical boxed warnings on varenicline and bupropion; the EAGLES trial did not find a significant increase versus placebo or NRT in patients with or without stable psychiatric illness, leading to FDA removal of the varenicline boxed warning.^[20]

Monitoring and discontinuation

• Follow up within 1-2 weeks of quit date and monthly during treatment; assess abstinence, adverse effects, mood, and adherence.^[5]
• Standard courses are 12 weeks; extending to 24 weeks or longer reduces relapse for varenicline and combination NRT.^[17]
• Withdrawal symptoms from nicotine itself peak in the first week and resolve over 2-4 weeks for most somatic symptoms; craving and dysphoria can persist longer.^[4]

Limitations of the evidence base

• Most landmark trials enroll motivated quitters in research settings; effect sizes in real-world clinical practice are typically smaller.^[5]
• Long-term (>12 month) abstinence data are limited for newer agents and for e-cigarettes as a cessation tool.^[23]
• Patients with severe mental illness, pregnant patients, and adolescents are under-represented in many cessation trials.^[8]

Tobacco-related disease tracks with age, pregnancy status, and psychiatric comorbidity; cessation strategies must adapt to each. Behavioral counseling is first-line in every special population; pharmacotherapy choice and intensity vary.^[5]

Pregnancy and perinatal

• Maternal smoking increases risk of low birth weight, preterm delivery, placental abruption, stillbirth, and sudden infant death syndrome.^[2]
• Behavioral counseling and incentive-based programs have the strongest evidence in pregnancy and are recommended as first-line.^[5]
• NRT in pregnancy: evidence is mixed; ACOG and USPHS support a shared-decision-making approach when behavioral treatment alone fails, preferring intermittent dosing (gum, lozenge) over the patch to reduce fetal nicotine exposure.^[5]
• Varenicline and bupropion are not routinely recommended in pregnancy because of limited safety data.^[5]

Pediatric and adolescent

• Most adult smokers initiate before age 18; adolescent initiation predicts lifetime dependence.^[2]
• E-cigarette use (vaping) among adolescents has surpassed combustible cigarette use in many high-income countries and is associated with later transition to combustible tobacco.^[2]
• Behavioral interventions have the strongest evidence in adolescents; NRT is sometimes used off-label for moderate-to-severe dependence with limited supporting evidence.^[5]
• Varenicline and bupropion are not FDA-approved for adolescents for tobacco cessation.^[6]

Geriatric

• Cessation at any age extends life and reduces cardiovascular and pulmonary morbidity; benefit accrues within months.^[13]
• Older adults tolerate NRT and varenicline well; monitor for drug interactions and renal dose adjustment of varenicline in significant renal impairment.^[6]

Severe mental illness and substance use comorbidity:

• Smoking prevalence is 2-3 times higher in patients with schizophrenia, bipolar disorder, and major depressive disorder than in the general population.^[8]
• The EAGLES trial established that varenicline and bupropion do not increase neuropsychiatric adverse events in stable psychiatric patients and remain first-line for this population.^[20]
• Smoking cessation does not worsen psychiatric symptoms when offered alongside usual care and may improve mood and anxiety over follow-up.^[5]
• Smoking induces CYP1A2; cessation can raise serum levels of clozapine and olanzapine by 30-50%, risking toxicity. Reduce doses proactively and monitor levels.^[6]

Cultural considerations

• Menthol cigarettes are disproportionately marketed to and used by Black/African American smokers in the United States; menthol is associated with higher dependence and lower quit success.^[2]
• Smokeless tobacco (chewing tobacco, snuff, gutka, paan) is prevalent in South and Southeast Asia and the Middle East; it causes oral, oropharyngeal, and pancreatic cancers and produces a dependence syndrome treated with the same pharmacotherapies.^[1-2]

Tobacco use disorder is a chronic relapsing condition. Most quit attempts fail on the first try, but repeated attempts substantially raise cumulative success, and abstinence at one year is highly predictive of long-term success.^[5]

Quit attempts and success rates

• Approximately 70% of current smokers report wanting to quit and 50% make a quit attempt each year, but unaided quit attempts achieve 12-month abstinence in only 3-5%.^[5]
• Combining behavioral counseling with pharmacotherapy roughly doubles to triples the odds of 12-month abstinence compared with no treatment.^[5,17]
• Most successful quitters require multiple attempts; the average is 6-30 attempts before sustained abstinence.^[5]

Health benefits of cessation

• Cardiovascular risk falls measurably within weeks; excess coronary heart disease risk is roughly halved within one year of cessation.^[2]
• Lung cancer risk falls progressively after cessation but does not fully normalize; risk approaches that of never-smokers only after 10-15 years.^[2]
• Quitting before age 40 returns nearly all the life-expectancy years that smoking would have cost.^[13]

Predictors of relapse

• High baseline dependence (FTND score, time to first cigarette under 30 minutes after waking), prior failed attempts, and psychiatric comorbidity predict relapse.^[12]
• Stressful life events, exposure to other smokers in the household, and concurrent alcohol use are common proximal triggers.^[5]

Tobacco use disorder rarely presents as a psychiatric emergency on its own, but acute nicotine withdrawal, nicotine toxicity, and inpatient smoke-free policies create predictable management problems.^[5]

Inpatient nicotine withdrawal

• Hospitalized smokers entering smoke-free facilities develop withdrawal within hours; untreated withdrawal contributes to irritability, against-medical-advice discharge, and pseudo-decompensation in psychiatric inpatients.^[5]
• Start NRT on admission for any patient who smoked within the past month; combination NRT (patch plus short-acting) is appropriate for heavier smokers.^[5]
• Provide brief cessation counseling and arrange post-discharge follow-up; inpatient-initiated cessation with post-discharge support increases quit rates.^[5]

Acute nicotine toxicity

• Acute nicotine poisoning presents with nausea, vomiting, salivation, abdominal pain, tachycardia, hypertension, tremor, and at high doses seizures, bradycardia, hypotension, respiratory failure.^[4]
• Sources include accidental ingestion of e-cigarette refill liquid (concentrated), pediatric exposure to nicotine gum or patches, and green tobacco sickness from dermal exposure in tobacco workers.^[4]
• Management is supportive: airway protection, IV fluids, benzodiazepines for seizures, atropine for severe bradycardia; activated charcoal if recent oral ingestion.^[4]

Suicide and psychiatric risk

• Smokers have higher rates of completed suicide than non-smokers; the relationship is partly mediated by psychiatric comorbidity rather than a direct effect of nicotine.^[8]
• Earlier FDA boxed warnings for varenicline and bupropion regarding suicidality were removed after the EAGLES trial found no excess of serious neuropsychiatric events versus placebo or NRT.^[20]
• Screen for mood, anxiety, and suicidality before and during pharmacotherapy in patients with psychiatric comorbidity; the diagnosis, not the medication, is the dominant risk factor.^[20]

Several aspects of tobacco cessation policy and practice remain actively contested in the literature and in regulatory guidance.^[5]

E-cigarettes as cessation aids

• A 2019 NEJM RCT found e-cigarettes superior to NRT for 12-month abstinence in motivated quitters receiving behavioral support, but many participants continued e-cigarette use at one year.^[23]
• Major guidelines (USPHS, USPSTF) do not yet endorse e-cigarettes as a first-line cessation tool, citing uncertainty about long-term safety, dual use, adolescent uptake, and product heterogeneity.^[5,15]
• Public health authorities differ: the UK NHS conditionally supports e-cigarettes for cessation; the US CDC and FDA emphasize harm-reduction caveats and youth-protection concerns.^[15]

Smoking and serious mental illness

• Whether routinely offering cessation pharmacotherapy in inpatient psychiatric settings is feasible and cost-effective remains debated; uptake historically has been low despite strong evidence of efficacy.^[8]
• Some experts recommend embedding tobacco cessation into routine SMI care, though high-quality implementation evidence is limited.^[8]

Cytisine access

• Cytisine is inexpensive and at least non-inferior to NRT in head-to-head trials, but remains unavailable in the United States; whether FDA approval is warranted is an active policy question.^[19]

Menthol and flavor regulation

• The FDA has proposed banning menthol cigarettes and characterizing flavors in cigars to reduce youth uptake and address health disparities; the public health impact and equity implications are debated.^[2]

Long-term safety of varenicline

• Post-marketing surveillance and the EAGLES trial have not confirmed earlier signals for serious neuropsychiatric or cardiovascular events; varenicline is now considered first-line.^[20]
• Limited evidence suggests caution in patients with recent acute coronary syndrome; some guidelines recommend deferring initiation for 2-4 weeks after an acute cardiac event.^[5]

• Tobacco use disorder is the leading preventable cause of death worldwide and accounts for more than 8 million deaths per year.^[1]
• DSM-5-TR diagnoses tobacco use disorder when at least 2 of 11 criteria occur within a 12-month period; severity is mild (2-3), moderate (4-5), or severe (6+).^[3]
• Nicotine acts at alpha4-beta2 nicotinic acetylcholine receptors in the ventral tegmental area to release dopamine in the nucleus accumbens.^[4]
• Nicotine half-life is approximately 2 hours; cotinine half-life is approximately 16-20 hours and is the standard biomarker of recent tobacco exposure.^[4]
• Nicotine withdrawal peaks within 1-3 days, lasts 2-4 weeks, and includes dysphoria, irritability, anxiety, difficulty concentrating, increased appetite, and insomnia.^[3,16]
• First-line pharmacotherapies are varenicline, combination NRT (patch plus short-acting), and bupropion SR; all are GRADE high-certainty.^[5,17]
• Varenicline (alpha4-beta2 partial agonist) has the highest single-agent efficacy in network meta-analyses.^[17]
• Bupropion is contraindicated in patients with a seizure disorder, active eating disorder, or recent benzodiazepine/alcohol withdrawal.^[6]
• The EAGLES trial showed varenicline and bupropion do not increase serious neuropsychiatric events compared with placebo or NRT, including in patients with stable psychiatric illness.^[20]
• USPSTF Grade A: clinicians should ask all adults about tobacco use, advise quitting, and offer behavioral interventions and FDA-approved pharmacotherapy.^[15]
• The 5 A's framework structures brief office-based intervention: Ask, Advise, Assess, Assist, Arrange.^[5]
• Smoking cessation raises serum levels of CYP1A2 substrates (clozapine, olanzapine, theophylline, caffeine) by 30-50% and may require proactive dose reduction.^[6]
• Quitting before age 40 returns nearly all the life-expectancy years that continued smoking would have cost.^[13]
• Smoking prevalence in patients with schizophrenia or bipolar disorder is 2-3 times that of the general population and is a major driver of excess medical mortality.^[8]
• The Fagerstrom Test for Nicotine Dependence (FTND) measures dependence severity; time to first cigarette under 30 minutes after waking is the highest-loading item.^[12]

No external funding. No conflicts of interest declared. Peer-review status: pending.