Consistent adherence to medication is essential because the HIV virus can quickly mutate if unsuppressed, resulting in drug resistance. In my experience, mental health problems and substance abuse are among the most significant barriers to adherence. Methamphetamine, a drug that is once again popular among gay men (a high-risk community), often results in drug runs that last several days during which no one is concerned about his medications. The same is true for other recreational drugs. People under the influence, despite their best efforts, will frequently miss doses. Therefore, anyone starting meds should be mindful of substance abuse issues. The same is true for mental health concerns. During the manic phase of a bipolar episode, for example, people rarely take their medications (or even feel the need for them). Likewise, someone experiencing depression may not care enough to worry about his or her meds. Anyone starting medications should work with health care providers to ensure that any mood disorders or substance abuse issues are as stable as possible.