Does Citalopram Cause Diarrhoea?
Yes, citalopram can cause diarrhoea, though it does so less frequently than some other SSRIs like sertraline. Diarrhoea is a recognized adverse effect of citalopram, occurring in approximately 8% of patients compared to 5% with placebo in controlled trials 1.
Evidence from FDA Labeling and Clinical Guidelines
The FDA drug label for citalopram clearly lists diarrhoea as one of the common adverse events, occurring in 8% of patients treated with citalopram versus 5% in placebo-treated patients 1. This represents a modest but statistically significant increase over placebo.
Importantly, citalopram causes diarrhoea less frequently than sertraline, which has been shown to have a higher rate of diarrhoea compared to citalopram and other SSRIs including bupropion, fluoxetine, fluvoxamine, mirtazapine, nefazodone, paroxetine, and venlafaxine 2.
Comparative Risk Profile
Among second-generation antidepressants, the gastrointestinal side effect profile varies considerably:
- Diarrhoea is among the most commonly reported adverse events across the SSRI class, alongside constipation, nausea, dizziness, headache, insomnia, and somnolence 2
- Research confirms that citalopram causes diarrhoea in clinical practice, with this effect being mild to moderate in severity in most cases 3
- A 2021 meta-analysis found that all commonly used antidepressants showed higher rates of gastrointestinal side effects than placebo, with escitalopram and sertraline being the least tolerated on the gastrointestinal tract 4
Clinical Implications
The diarrhoea associated with citalopram is typically mild to moderate and transient, occurring early in treatment 3, 5. The excess incidence over placebo is less than 10% 3.
Key Clinical Considerations:
- Nausea is more common than diarrhoea with citalopram (21% vs 8%), and nausea/vomiting are the most frequent reasons for treatment discontinuation in efficacy studies 1, 2
- The gastrointestinal effects are generally not dose-dependent for diarrhoea specifically, unlike some other adverse effects such as fatigue, insomnia, and somnolence which show positive dose-response relationships 1
- Citalopram has minimal anticholinergic effects, which distinguishes it from tricyclic antidepressants and may contribute to its gastrointestinal side effect profile 5
Management Approach
When prescribing citalopram, counsel patients that:
- Diarrhoea may occur in approximately 1 in 12 patients (8%) 1
- This side effect is usually mild and may resolve with continued treatment 3
- If gastrointestinal side effects are particularly problematic, consider alternative agents such as mirtazapine, which has been shown to have fewer gastrointestinal side effects overall 4
The overall safety profile of citalopram remains favorable, with no clinically relevant effects on cardiac or laboratory parameters, and the gastrointestinal effects are generally well-tolerated in both short- and long-term use 3.