People with PTSD are at higher risk for other mental health disorders. They are also more likely than those without PTSD to experience cardiovascular problems, obesity, chronic pain, diabetes, and a wide range of other physical ailments. As a result, many people with PTSD are on some kind of medication. Taking medication as it is prescribed for a medical condition (for example, high blood pressure, diabetes, high cholesterol) is a very important health behavior that can reduce the risk for physical health problems or complications associated with certain medical or mental health conditions.
In this article from About.com, you can learn more about a study that looked at the effect of PTSD on medication adherence. You can also learn why PTSD might negatively impact medication adherence.