High-caution groups include pregnant or breastfeeding people, those with significant liver disease, unstable thyroid disorders, certain autoimmune conditions, and users of sedative medicines. Anyone on regular medication (antidepressants, blood pressure or diabetes drugs, immunosuppressants, etc.) should not start without medical advice due to interaction risk. If you have upcoming surgery, inform your clinician as well. “Avoid without clinician approval” is often the safer framing, because risk profiles vary by individual.