From websites;
The following symptoms, anxiety, agitation, panic attacks, insomnia, irritability, hostility, aggressiveness, impulsivity, akathisia (psychomotor restlessness), hypomania, and mania, have been reported in adult and pediatric patients being treated with antidepressants for major depressive disorder as well as for other indications, both psychiatric and nonpsychiatric. It should be noted that VIIBRYD is not approved for use in treating bipolar depression.

And, on the positive side;
Viibryd: Sharing of experience with it - Bipolar Support Forum