Through global sensitivity analysis, we found that the parameters most sensitive to the endemic addicted and recovery populations were \(\zeta\), the rate at which addicts enter treatment, and \(\delta\), the rate at which recovering addicts successfully complete treatment. We found that model parameters related to new addictions, such as \(\beta_1\), \(\gamma\) and \(\alpha\) are much less impactful. This suggests that encouraging addicted individuals to seek treatment and working to increase its effectiveness are of utmost importance in reducing the total number of people affected by this crisis. While preventing new addictions is of course helpful, our result underscores the fact that we currently a large population of individuals stuck in addiction. Interventions, then, must directly address rehabilitating that population - there is no other pathway through which these individuals can move back to the susceptible group and be free of addiction.