You're better off matching reimbursement eligibility with information you can manage, like the source of the reimbursement claim & its general purposes, rather than attempting to impose an ad hoc formulary.
For example, you might ask questions like these about the claims:
Does the care it contributes to fit the definition provided by
IRS Publication 502 (click the Medical Care subtopic)?
Was the Rx ordered by a physician or other credentialled medical practitioner authorised to write scripts, for treatment of an identified medical condition? Does the provider attest that the treatment is "primarily to alleviate or prevent a physical or mental defect or illness" (quote from Pub 502 definition of Medical Care)?
There's no one correct way to reach determinations of what claims qualify or not--that's the beauty, & for some the aggravation, of spending accounts. If you work in a way that's consistent, sensible, fair, and that doesn't require you to be a pharmacist, who can find fault with that?