The Fetzima works as an antidepressant and is often prescribed to treat anxiety, although it may not always be approved for this specific condition. It is not used to treat hypersomnia. Common side effects of Fetzima include nausea, possible increased heart rate, increased sweating, and constipation. If you are already being treated for anxiety and emetophobia, it is important to consult with your healthcare provider before starting a new medication.