Shadow formulary (n.) — the consumer AI already in routine clinical use that no hospital approved, procured, tested or logged.
Named by analogy to the drug formulary: the approved list nothing reaches a patient without passing through. The shadow formulary is everything that reaches the patient without passing through anything.
Coined by BenchEval founders on The Signal Room, 23 June 2026.
Every hospital runs a drug formulary — the approved list. Nothing reaches a patient until it is vetted, dosed and signed off. It is how we gatekeep anything that carries risk.
The shadow formulary is the one nobody approved. ChatGPT, Claude, Gemini — already in constant clinical use, but in no formulary, governed by no one, logged nowhere. And it is not just patients. It is clinicians. The most-used reference on a shift is not a guideline on a shelf; it is whatever model the patient opened in the waiting room, or the doctor opened while waiting on bloods.
A governance committee cannot see it, because nobody bought it. No contract, no procurement trail, no log. It did not come through the front door — it is in everyone’s pocket.
None of this is newly discovered. The security and compliance literature has documented the same phenomenon for years under the name shadow AI — unsanctioned tools entering an organisation through the people who work there rather than through procurement, and the register of controls that follows from it. What “shadow formulary” changes is the department the problem belongs to. Shadow AI is an IT and information-security problem, owned by a CISO and measured in data leakage. A shadow formulary is a clinical governance problem, owned by the people accountable for patient safety and measured in what reaches a patient. Naming it as a formulary names the control, because every hospital already knows what a formulary requires.
A formulary is a process that runs, not a document that exists.
- 01
A committee approval is a document from six months ago. A scenario set you re-run is a live control.
- 02
You re-check a drug interaction every time the prescription changes. A formulary is a process that runs, not a PDF.
- 03
Give the risk a name — a named clinical safety owner, a person rather than a committee.
A note on scope: “shadow formulary” names a governance gap, not a model failure mode. It is not a code in the Standard’s failure taxonomy, not a severity level, and not a grading dimension.