citalopram and aspirin

Pharmacodynamic interaction: citalopram, as a selective serotonin reuptake inhibitor, reduces platelet serotonin levels and impairs platelet aggregation. Aspirin irreversibly inhibits cyclooxygenase-1, decreasing thromboxane A2 production and platelet function. The additive effects on haemostasis increase the risk of bleeding, particularly from the gastrointestinal tract.

Concurrent use of citalopram and aspirin is associated with a significantly increased risk of upper gastrointestinal bleeding, including peptic ulcer haemorrhage. This risk is further heightened in patients with a history of peptic ulcer disease, concurrent use of anticoagulants, older age, or high-dose aspirin therapy. Bleeding can present as melaena, haematemesis, or occult blood loss leading to anaemia.

Assess the need for aspirin and citalopram co-prescription. If aspirin is required for cardiovascular protection, consider gastroprotective measures such as a proton pump inhibitor. Use the lowest effective doses of each drug. Monitor for signs of gastrointestinal bleeding (e.g., black stools, anaemia) and evaluate haemoglobin periodically. Consider alternative analgesia or anticoagulation strategies where appropriate, and avoid concurrent use in high-risk patients unless benefits clearly outweigh risks.

The interaction is well established. Multiple observational studies and meta-analyses have shown an increased risk of upper gastrointestinal bleeding with SSRIs and antiplatelet agents, including aspirin. The risk is additive and recognised in major clinical guidelines and drug interaction databases.