Pharmacology · Smoking cessation medicines
Cytisine !
A plant alkaloid that is a nicotinic partial agonist, used to quit smoking. WHO added it to the essential medicines list in 2025.
Updated 2026-11-01
Also called: Cytisinicline (INN)
The figure shows nicotine, which binds the same site, in the human α4β2 nicotinic receptor; cytisine has only been solved with model proteins (acetylcholine-binding proteins), not the human receptor.
Mechanism of action
Cytisine is a plant alkaloid and a partial agonist at nicotinic acetylcholine receptors, with affinity for the α4β2 subtype. Like varenicline, which was developed from it, it eases craving and blocks part of nicotine's reward.
- Binds α4β2 nicotinic receptors as a partial agonist
- Partial stimulation eases craving
- Nicotine from smoking rewards less
Pharmacokinetics
- Absorption
- Taken by mouth
- Half-life
- About 5 hours
Indications
- Aid to stopping smoking and tobacco use, with counselling and behavioural support Tobacco use disorder →
Adverse effects
Common
- Gastrointestinal upset (mostly mild)
- Sleep disturbance
Contraindications
- Hypersensitivity to cytisine
Key interactions
- Theophylline, warfarin, insulin (effect of quitting smoking)
- Their effects may change after stopping smoking; doses may need review
- Continued smoking
- Less benefit; the plan is to stop tobacco completely
What is monitored
- Smoking status
- Gastrointestinal and sleep complaints
Administration and safety
- Given by mouth over a set course, with a planned quit date
- Combined with counselling or behavioural support
Nursing care
- Agree on a quit date and follow-up
- Ask about nausea, stomach upset and sleep
- Review medicines whose effect changes when smoking stops
Pregnancy and breastfeeding
Not established in pregnancy; behavioural support comes first.
Test yourself
Think of the answer, then tap the question to see it.
What is the relation between cytisine and varenicline?
Varenicline was developed from cytisine; both are nicotinic partial agonists.
In which year did cytisine enter the WHO essential medicines list?
2025, on the core list.
Which adverse effects are reported most often with cytisine?
Gastrointestinal upset and sleep disturbance.
Related drugs
Related conditions
← Back to the class: Smoking cessation medicines
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: Cytisine (cytisinicline) (World Health Organization (eEML), 2025); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 13 (McGraw Hill, 2023); WHO releases first-ever clinical treatment guideline for tobacco cessation in adults (World Health Organization, 2024); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).
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Representative model, for educational purposes only.