The dramatic increase of opioid use and abuse has become a crisis in the United States. To tackle this crisis, the necessary first step is to understand the behavioral processes of its consumers. Recent years, Twitter has become one of the most popular social media platforms that can provide researchers with real-world insights into users health behaviors. In this work, we collected and evaluated a large number of tweets related to opioid us and abuse in terms of 4 aspects: 1) a general overview of the discussions related to opioids on Twitter; 2) the prevalence of co-use of opioids and other substances; 3) the trajectory of an individuals opioid use behavior, i.e., from the first time that the substances were taken to regular use; and 4) the consumer vocabulary used by the laypeople. The preliminary results demonstrated that Twitter can provide valuable insights on opioid use and abuse, as well as the nexus of alcohol consumption, opioid use, and pain management.