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Nicotine dependence matters because withdrawal symptoms drive continued smoking as much as the pleasurable effects of nicotine itself, and because smoking changes how other prescribed drugs are metabolised. It is diagnosed as a pattern of compulsive tobacco use with toleranceNeeding a larger dose of a drug over time to get the same effect.Read more →, craving, and withdrawal symptoms, such as irritability, anxiety, difficulty concentrating, and increased appetite, on stopping. For example, imagine a heavy smoker admitted to hospital who becomes irritable, restless, and intensely craves a cigarette within hours of admission. In practice, recognising this as nicotine withdrawal, not a new psychiatric problem, avoids unnecessary investigation.

The Fagerström Test for Nicotine Dependence is a brief, validated questionnaire used to grade severity, with time to first cigarette after waking being one of its most heavily weighted questions. Cigarette smoke, not nicotine itself, induces the liver enzyme CYP1A2 (cytochrome P450A family of liver enzymes that break down most drugs, and a common site of drug interactions.Read more → 1A2), which speeds up the metabolism of drugs such as clozapine and olanzapine, so smoking status changes the doses these drugs need. Picture a patient on clozapine who suddenly stops smoking on admission to a smoke-free ward: clozapine levels can rise sharply because CYP1A2 induction falls away, risking toxicity. In practice, checking smoking status, and re-checking it whenever it changes, is essential whenever prescribing CYP1A2-metabolised drugs like clozapine.

• A patient stable on clozapine stops smoking abruptly during a hospital admission. What must be anticipated?
• Which nicotine replacement approach gives the best quit rates for a heavily dependent smoker?
• What happens to anxiety and depressive symptoms in people with mental illness who successfully stop smoking?

• Nicotine withdrawal, irritability, craving, and increased appetite after stopping smoking, unlike caffeine withdrawal's more prominent headache and fatigue.
• Smoking (not nicotine alone), induces CYP1A2, whereas nicotine replacement therapy, such as patches or gum, does not induce this enzyme.
• Clozapine toxicity risk, rises when a smoker suddenly stops, unlike a stable non-smoker, whose clozapine level is not affected by CYP1A2 induction changes.
• Nicotine dependence, graded by the Fagerström Test, rather than by Edwards and Gross's criteria, which describe alcohol dependence syndrome specifically.

• The white cell count is monitored for agranulocytosis and is not driven by smoking status.
• The dose usually needs reducing rather than increasing.
• The direction is reversed, since levels rise once the enzyme inductionA drug increasing the amount or activity of a liver enzyme, which speeds up the breakdown of other drugs it shares that enzyme with.Read more → is withdrawn.
• This is one of the most clinically important smoking interactions in psychiatry.
• A low-strength patch alone under-treats a heavily dependent smoker.

• Extract the defining phenomenology, duration, severity and functional-impact clues.
• Match the pattern to the most specific diagnostic or assessment construct.
• Actively test the closest look-alike against the missing or contradictory clue.
• Choose the precise term rather than a broader category that is merely compatible.