Euthymia, which refers to a state of stable mental health and happiness, has several antonyms that describe the opposite feeling. These antonyms include depression, anxiety, sorrow, gloom, sadness, despair, hopelessness and misery. Though these are different emotions, they're all opposite to the feeling of euphoria. Depression, anxiety and despair signify the lack of positive feelings, while sadness, gloom and hopelessness mark the presence of negative emotions that impede contentment. So, people who demonstrate these emotions can be said to be in a state of distress. Therefore, it's crucial to practice self-care and seek professional help when experiencing these antonyms of euthymia.