An over-the-counter product does not have to be approved by the FDA, but you do have to do your homework so you can substantiate your claims if challenged. Why not check out the FDA website and learn about this? A 5 minute search found this --
"Bringing Nonprescription Drug Products to the Market Under an OTC Monograph
"OTC drugs can be brought to the market following the NDA process as described above or under an OTC monograph. Each OTC drug monograph is a kind of "recipe book" covering acceptable ingredients, doses, formulations, labeling, and, in some cases, testing parameters. OTC drug monographs are continually updated to add additional ingredients and labeling as needed. Products conforming to a monograph may be marketed without FDA pre-approval...."
If you think your products might be prescription drugs, then that's a whole other story. In this case, the real issue is the deep pockets needed to do efficacy testing. And that testing doesn't necessarily guarantee FDA approval.