Medication adherence is one of the biggest challenges doctors face when trying to control chronic conditions such as diabetes and heart disease, and now a study suggests that when patients are switched to generic medications with a different color or shape, they’re more likely to stop taking the drug.

In the study published last week in the journal JAMA Internal Medicine, researchers from Brigham and Women’s Hospital culled through a database of patients who stopped taking anti-seizure medications for epilepsy and found that those who had been switched to a generic medication that looked different from their previous prescription were more likely to have discontinued their treatment.