What the batch code can tell you
For Listerine, the batch code can support a freshness check and help you compare whether a seller's stock looks unusually old.
It can also help identify obvious mistakes, such as a claimed new release with a very old production window.
What it cannot prove
A batch code cannot verify the full supply chain, storage conditions, tamper history, or whether a seller is authorized.
A counterfeit product may carry a copied code, and a genuine product may still be unsuitable if it was badly stored or opened.
A better buying-risk workflow
Use the Listerine checker first, then compare packaging print quality, seller history, price realism, return policy, and whether the code appears consistently on box and product.
If the product may be unsafe, stop using it and contact the brand or retailer with clear photos of the code and packaging.
Listerine product and package comparison notes
Do not use a decoded manufacturing estimate to extend a printed expiry. A missing or broken tamper feature, leaking cap, altered liquid, or unknown transfer into another bottle is a separate reason for caution.
Keep mouthwash in its original labeled container and avoid topping up a partially used bottle, which can mix lots and obscure contamination.