Just for a comment;
I have a Q＆A about the approval route for drugs, but according to FDA's website, drugs and OTCs have different approval routes. Therefore, the way you look for evidence about OTC may be different.
The Amazon's site of this product has following description;
Statements regarding dietary supplements have not been evaluated by the FDA and are not intended to diagnose, treat, cure, or prevent any disease or health condition.
But it is certainly strange that Cetirizine HCl is being treated as a dietary supplement. I believe there is sufficient reason for the questioner to be confused.
■Who is the Sda Laboratories ?
According to this site, sda Laboratories Inc. labeler's code (NDC) is 66424. The labeler has 12 products that have an assigned National Drug Code. Thus, the SDA appears to be a company that has at least an approved OTC.
■FDA's OTC list
The FDA's list of OTCs is this site but when I try to find an OTC that has apparently been approved, I don't get any hits. This database doesn't seem to be user-friendly in the least.
This FDA's site has following descriptions;
For each category, an OTC drug monograph is developed and published in the Federal Register. OTC drug monographs are a kind of "recipe book" covering acceptable ingredients, doses, formulations, and labeling. Many of these monographs are found in section 300 of the Code of Federal Regulations.
Once a final monograph is implemented, companies can make and market an OTC product without the need for FDA pre-approval. These monographs define the safety, effectiveness, and labeling of all marketing OTC active ingredients.
If it's OTC monograph drugs, then maybe they don't need FDA approval.
However, I have yet to find a list of FDA's OTC monographs.
I'm still learning how to find out what basis the drug authorities used to evaluate the effectiveness and safety of the product.
If there are any errors or constructive comments, I welcome them.