Warfarin plasma levels can be increased by
fluvoxamine and raised INRs have been seen in several cases. Isolated reports describe raised INRs and/or haemorrhage in patients taking acenocoumarol with citalopram or
paroxetine, and
warfarin with fluoxetine or
paroxetine.
SSRIs alone have, rarely, been associated with bleeding.
Studies have not demonstrated a consistent interaction, perhaps with the exception of
fluvoxamine and
warfarin. It may be prudent to monitor the INR when
fluvoxamine is first added, being alert for the need to decrease the anticoagulant dosage. Consider monitoring with other
SSRIs, but note only a few patients appear to have demonstrated this interaction. Any interaction appears to occur in about the first 2 weeks of treatment.