Selective serotonin reuptake inhibitor (SSRI)
Citalopram and smoking: how tobacco affects the medication
Tobacco smoking is one of the most underappreciated drug-drug interactions in chronic medication. Compounds in tobacco smoke induce hepatic enzymes (especially CYP1A2) and can shift the plasma concentration of many medications, including Citalopram (Citalopram), enough to matter clinically at 10mg, 20mg, 40mg.
How smoking affects Citalopram
Polycyclic aromatic hydrocarbons in tobacco smoke induce CYP1A2 and to a lesser extent other CYP enzymes. For medications metabolised primarily by CYP1A2, smokers can have plasma levels 30–50% lower than non-smokers at the same dose. Whether Citalopram is affected depends on its specific metabolic pathway. Citalopram selectively inhibits the serotonin reuptake transporter, increasing synaptic serotonin availability with limited affinity for noradrenaline transporters or other receptors.
Practical guidance
According to the prescribing information for Citalopram, smoking status should be disclosed at every dose review of Citalopram. Stopping smoking can paradoxically raise plasma levels of CYP1A2-metabolised medications enough to cause new-onset side effects within days, and may require a temporary dose reduction. The 10mg, 20mg, 40mg starting strength assumed in the prescribing information is usually for non-smokers.
Frequently asked questions
Does smoking change how Citalopram works? ▾
For medications metabolised by CYP1A2, yes — smokers may need higher doses or have reduced effect at standard 10mg, 20mg, 40mg. Whether Citalopram specifically is affected depends on whether Citalopram uses CYP1A2. The prescribing information notes any documented interaction.
Will I need to adjust Citalopram if I quit smoking? ▾
Possibly, if Citalopram is one of the medications affected by CYP1A2 induction. Stopping smoking restores CYP1A2 to normal within days, raising plasma levels and potentially causing side effects. Discuss the timing of any dose adjustment with the prescriber when planning to quit.
Products containing Citalopram
More on Citalopram
- With alcoholCitalopram and alcohol — is it safe to drink?
- With foodShould Citalopram be taken with food?
- Side effectsCitalopram side effects: common, rare and warning signs
- Dosage guideCitalopram dosage guide: how much to take and when
- OnsetHow fast does Citalopram start working?
- DurationHow long does Citalopram last?
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