Greater Glasgow and Clyde Medicines

Citalopram/escitalopram & QTc prolongation reminder

Key messages

  • Use of citalopram/escitalopram is contraindicated:
    • in combination with other medication known to prolong QTc interval
    • in patients with known QTc interval prolongation or congenital long QT syndrome
  • A recent investigation reported a failure to carry out ECG monitoring as per recommendations for a patient on a combination of citalopram and zuclopenthixol decanoate.


The MHRA issued a Drug Safety Update in 2011 (updated in 2014) indicating the contraindications above and a reduction of the maximum daily doses.

  • Citalopram maximum daily dose:
    • 40 mg for adults
    • 20 mg for adults older than 65 years
    • 20 mg for those with hepatic impairment
  • Escitalopram maximum daily dose for adults older than 65 years and those with hepatic impairment was reduced to 10 mg/day

Due to the recent investigation reporting a failure to carry out appropriate ECG monitoring, this blog serves as a reminder of the issues prescribers should consider when prescribing QT prolonging medicines.

As the use of citalopram/escitalopram with other medicines known to prolong QTc interval is contraindicated, this combination would be unlicensed. When prescribing medications off licence, a clear rationale should be documented in the patient’s medical notes after a discussion, regarding the risks, with the patient and carers.

Before starting a contraindicated combination, a baseline ECG is required followed by a further ECG once the medicine reaches steady state, including after any dose changes. If long term use of two medicines that can prolong the QT interval is deemed necessary the patient should be followed up and monitored via specialist clinic.

Although literature differs, a QTc interval of > 450 ms in males and > 460 ms in females is considered borderline prolonged. Consideration should be given to dose reduction of QT prolonging drugs or changing to an alternative non QT prolonging drug.

A QTc interval > 500 ms is clinically significant and likely to confer an increased risk of arrhythmia. Any drugs which prolong the QT interval should be reviewed immediately.

Details of drugs that are known to be associated with QT prolongation can be found via crediblemeds or NHSGGC Medicines Update Extra Bulletin: Drug induced QTc prolongation.


Published 08/09/2021. Medicines Update blogs are correct at the time of publication.