Citalopram and Escitalopram can prolong the QT interval and should be avoided with concomitant QT-prolonging agents such as atypical antipsychotics.
“Prolongation of the QT interval is an important medication adverse effect to consider. This is particularly true in patients taking multiple medications, because this effect can be additive and increases the risk of life-threatening arrhythmias such as torsades de pointes. Among commonly used antidepressants, citalopram and escitalopram may prolong the QT interval. Other SSRIs, as well as bupropion, venlafaxine, and mirtazapine, do not have this effect. Both tricyclic antidepressants and antipsychotics, commonly used in patients also taking SSRIs, can cause QT prolongation, making their combined use problematic.” ABFM
“Fluoxetine is the only medication with consistent evidence showing that it improves depression symptoms in children and adolescents, including a Cochrane review of three randomized trials. Escitalopram is licensed for treatment of depression in children 12 and over, and consensus guidelines also recommend
the use of citalopram and sertraline as first-line treatment in children and adolescents. However, these drugs do not have the same level of evidence for their effectiveness as fluoxetine. ” ABFM
Reference
http://www.aafp.org/afp/2015/0715/p94.html
http://www.aafp.org/afp/2010/0301/p617.html
http://www.aafp.org/afp/2012/0301/p483.html