In the field of psychiatry, diagnoses continue to be based primarily on symptoms, not by clearly delineated underlying biological mechanisms. For example, what we diagnose as schizophrenia have variability in symptom presentation. Additional research is needed to help organize a diagnostic system based on underlying biology (this is the essence of the Research Domain Criteria (RDoc) effort at NIMH). Until more precise science is available, psychiatric medication treatments can have partial effects for some symptoms and not address others. Every person is also different in multiple dimensions like family history, trauma history, current stressors and prior diagnoses, and medical and psychiatric medication history. So, while one medicine may work for one person with a psychiatric condition, another patient with the same diagnosis may require different regimen. The research on polypharmacy is also incomplete. Sharing the research uncertainty when appropriate and addressing both symptoms and side effects, as well as patient experience, can be good pathway forward. Clinical guidelines can be informative for how to think about adding medications, and there is research to support some combination treatments. The American Psychiatric Association Practice Guidelines can be found here. It’s important for patients and their families to understand the challenges presented in determining the best medication treatments for their specific conditions, and why changes can occur frequently at the beginning of treatment. Understanding that psychiatry is an art as well as a science can be helpful for the patient and family, and underscore the importance of all involved sharing information openly with the treating professional.