Factors contributing to poor medication adherence are myriad and include those that are related to patients (e.g., suboptimal health literacy and lack of involvement in the treatment decision–making process), those that are related to physicians (e.g., prescription of complex drug regimens, communication barriers, ineffective communication of information about adverse effects, and provision of care by multiple physicians), and those that are related to health care systems (e.g., office visit time limitations, limited access to care, and lack of health information technology). Because barriers to medication adherence are complex and varied, solutions to improve adherence must be multifactorial.