Expert answer:
Depends on antidepressant.
Most of currently used antidepressants is low or very low risk for breastfeeding, that is, it is safe and can take:
Sertraline, Fluoxetine, Amitriptyline, Clomipramine, Imipramine, Nortriptyline, Citalopram, Escitalopram, Paroxetine, etc.
However, there are others antidepressants which have a high or very high risk and should not be used during breastfeeding: Nefazodone, Tranylcypromine, etc.
The doctor who prescribed the antidepressant may advise whether or not the drug is allowed during breastfeeding.
