I hate it when an insurance company “plays doctor”, most likely to reduce their expense.  You should include your doctor’s statement that VSL 3 DS is medically necessary for your condition and that other treatment options have not been effective.  Did BCBS give you a reason why they are no longer covering this prescription?  My wife had this problem with one of her prescriptions, but persistence in presenting her case eventually worked.

I agree it is very frustrating.  I agree with Bill, have a doctors statement and I would suggest your have your own statement, an adjuration almost, stating your reasons/observations for VSL 3 DS (I also have BCBS).  I appealed and with extreme verbiage and it can be approved.  I appealed for Dexilant (heartburn) and BellaDonna suppositories (Cuffitis).  Persevere Jill - you should get what you need for your condition!

I successfully appealed the Maryland BCBS denial of VSL #3 DS. The first appeal took almost a year in total and was only successful when I finally escalated it into a complaint to my state's insurance regulator. A good doctor's letter is essential. Please send me a Private Message if you'd like me to share the language that ultimately worked for me, which you could offer your doctor to save their time.

My husband had a doctor's letter to an appeal to our beloved prescription company.  That did jack (you know what), they insisted the VSL DS was over the counter.  Unreal.  So my husband is just going to keep downloading coupons from VSL's site and our pharmacist will also implement a VSL discount since we are going to pay out of pocket.   Comes down to $150 for 3 months instead of $300.  Better than nothing. 

If you don't go beyond the insurance company-managed appeals then you're unlikely to succeed. 

Ultimately I caused CareFirst BlueCross to develop a fairly liberal policy wrt VSL #3 DS.

The key language is:
"VSL#3-DS®, available by prescription only as a medical food, may be considered medically necessary for the dietary management of an ileal pouch and ulcerative colitis.
Non-prescription probiotics are available over-the-counter (OTC) and are not covered."

If you're interested in the whole thing (referencing it could be quite helpful in an appeal) it's at:
http://notesnet.carefirst.com/...04EE6AE?OpenDocument

CareFirst BlueCross has moved the location for their policy statement supporting the coverage of VSL #3 DS in the maintenance of an ileal pouch. It looks like it’s best approached from this link: https://provider.carefirst.com.../medical-policy.page

Click on the “Medical Policies” button and search for “Probiotics,” and select the Probiotics document from the list (of two). I think the site really wants you to agree to the disclaimer that sometimes shows up.

Insurance companies aren’t bound by the medical policy statements written by other insurance companies, but such policies can be influential, especially to suggest to a state insurance bureau that an insurance company is being unreasonable.