Adherence to asthma medications is generally poor and undermines clinical outcomes. Poor adherence is characterized by underuse of inhaled corticosteroids (ICS), often accompanied by over-reliance on short-acting β2-agonists for symptom relief. To identify drivers of poor medication adherence, a targeted literature search was performed in MEDLINE and EMBASE for articles presenting qualitative data evaluating medication adherence in asthma patients (≥12 years old), published from January 1, 2012 to February 26, 2018. A thematic analysis of 21 relevant articles revealed several key themes driving poor medication adherence, including asthma-specific drivers and more general drivers common to chronic diseases. Due to the episodic nature of asthma, many patients felt that their daily life was not substantially impacted; consequently, many harbored doubts about the accuracy of their diagnosis or were in denial about the impact of the disease and, in turn, the need for long-term treatment. This was further compounded by poor patient-physician communication, which contributed to suboptimal knowledge about asthma medications, including lack of understanding of the distinction between maintenance and reliever inhalers, suboptimal inhaler technique, and concerns about ICS side effects. Other drivers of poor medication adherence included the high cost of asthma medication, general forgetfulness, and embarrassment over inhaler use in public. Overall, patients' perceived lack of need for asthma medications and medication concerns, in part due to suboptimal knowledge and poor patient-physician communication, emerged as key drivers of poor medication adherence. Optimal asthma care and management should therefore target these barriers through effective patient- and physician-centered strategies.