Objective: Among untreated adults, functional impairments associated with ADHD are widespread and cumulative, and can include social, educational, and professional impairments, increased risk of accidents and mortality, and reduced quality of life. Here, we review the most prominent functional impairments in adults with ADHD and summarize evidence describing the potential role of medication in improving outcomes. Method: Articles related to the search terms “ADHD,” “adult,” and functional impairments were identified through Google Scholar and PubMed and selected for inclusion based on four criteria: strength of evidence, relevance to current challenges in adult ADHD, impact on the field, and recency of the results. Results: We identified 179 papers to support the conclusions on the relationship between ADHD and functional impairments, and the impact of pharmacological therapy on functional impairments. Conclusion: This narrative review provides evidence that pharmacological treatment can be effective in minimizing not only the symptoms of ADHD, but its functional consequences as well.