If scientists publish solid evidence that fluoxetine and psychedelics don't mix well, the FDA might put out official written guidance telling researchers how to handle this in clinical trials. But FDA guidance takes 18-36 months to write after the data comes out. For that to happen by mid-2027, the science would already need to be published and in FDA's hands by mid-2025. That timeline is tight and probably won't happen.
FDA guidance development timelines typically run 18-36 months from data publication to finalized guidance. For this prediction to resolve TRUE by Q2 2027 (June 2027), the underlying data would need to be sufficiently compelling and already in FDA's review pipeline as of mid-2026. A formal guidance document — as opposed to informal safety communications or investigator letters — requires internal review, public comment, and finalization. Informal safety communications are more likely in this window than formal guidance. Confidence reduced from 0.74 to 0.45. Resolve condition clarified: requires formal FDA guidance document or protocol amendment requirement, not merely an FDA safety communication.