As a general rule, medication side-effects with sertraline
are usually seen only in the initial days of treatment.
What is the illness for which she has been prescribed sertraline?
In most cases it is anxiety
Sertraline 50 mg may not be sufficient for an active episode of depression or anxiety. It may help to prevent an episode, but if she is having a relapse of depression or anxiety, then the dose may need adjustment. Even if she has been regularly taking 50 mg sertraline per day, she may be having a recurrence of illness (in a mild form).
You can take her once to her psychiatrist
who can assess the current situation and advice accordingly.