You can bring 50 doses of something back without a prescription...When I was laid off I did this to get my thyroid pills. I went to a pharmacy that was a true pharmacy and bought name brand (Pfizer) thyroid pills in my dosage...50 doses in a plastic bag so the border agents can see. If the drugs were not "Getting High Drugs," there was not a lot of drama. I did this several times.
Edit: It was Nuevo Laredo...I would drive southward down TxHwy59 in the afternoon...Make my buy...drive back up IH35 up to San Antonio, then back to Houston on IH10.