About 10 years ago, my cousin lived in San Diego. She was a lifelong diabetic and used to cross the border regularly to purchase her insulin, because it was so much less expensive. She would buy as much as she could, and did it several times over the course of a few years, until one time when she was coming out of the pharmacy and Mexican authorities arrested her and threw her in jail. Apparently they'd had their eye on her, and hit her with charges that effectively amounted to "smuggling" and"intent to deliver". She spent almost 4 months in custody, before my uncle was able to get her out. Not a good situation. Not saying this is something that happens often, but in her case, it was pretty awful.