If they’re being used to cover PEDs, they’re masking agents, and that’s a ban.
If not, then you need a document. I forget the name of it. It’s essentially a doctor’s not to MLB saying the medication is prescribed. Chris Davis of the Orioles takes Adderall, a medication for ADD, and he got suspended by MLB under the drug protocol a few years ago because he forgot to file the paperwork.
That was back in 2014. Here is a link.
https://www.mlb.com/news/orioles-chris-davis-suspended-25-games-for-amphetamines/c-94335720
The piece of paper is called a “therapeutic use exemption.”