Neither are a problem. Typically, you don't get repeat business if you're selling fake pills, so online sellers of prescription drugs almost always provide you with what you're buying. This applies to both prescription drugs as well as recreational drugs purchased through darknets.

Regarding DHS and CBP, both are overblown concerns. You'll receive a letter in the mail noting they've confiscated the material in question, which you usually send to the seller who will replace the shipment at no charge to you.