I always keep capstar on hand and it is not rx.Bravecto is an FDA product (oral) by prescription only. Anything oral is by Rx only. That is why heartworm, oral flea and tick meds are by Rx only.
As far as food goes, Hill's Derm Defense has shown a lot of promise on managing allergies. Best oral medication for allergies is Apoquel. Only successes no failures yet.