Buying Prescription Drugs in Mexico

A few weeks we took a cruise from Florida to LA through the Panama Canal, the last 2 stops being at ports in Mexico. When we arrived in LA and went through immigration we were asked if we had bought any prescription drugs while in Mexico.

We had not bought any but it just has me wondering what the laws are regarding this. If we had bought any would the next question have been about the quantity,  or maybe paying duty on them? (We are both US citizens)

I found this:

https://www.tripsavvy.com/buying-prescription-drugs-in-mexico-2677514

I found this:

https://www.tripsavvy.com/buying-prescription-drugs-in-mexico-2677514

Thanks for doing the legwork on this. That weblink explains a lot, including:

You must declare the drugs at Customs upon your return. Customs permits people to bring back reasonable amounts of medications for personal use but does not allow stockpiling or purchasing large amounts of drugs for what will be assumed is a commercial or resale purpose. If the medication is a controlled substance, a reasonable amount means up to 50 combined total doses.
If you do bring a prescription drug that is a controlled substance into the U.S. from Mexico, it must be for legitimate personal medical use. It should be in the original container, which must identify the substance and the name and address of the dispenser

As a general rule of thumb, you can bring back medicines from another country if they're for your personal use and the quantity isn't excessive.  Prescriptions, including controlled dugs, should be in original containers with your information and the information of the prescriber/dispenser clearly visible.

What can get a bit tricky is if the drug is licensed in the origin country but not licensed in the US. 

A few weeks we took a cruise from Florida to LA through the Panama Canal, the last 2 stops being at ports in Mexico. When we arrived in LA and went through immigration we were asked if we had bought any prescription drugs while in Mexico.

We had not bought any but it just has me wondering what the laws are regarding this. If we had bought any would the next question have been about the quantity,  or maybe paying duty on them? (We are both US citizens)

You can buy them in Mexico, but you can't bring them into the USA without an import license, I believe, if they are controlled substances and in any but minimal quantity. Although I used to walk across the border at Teacate and buy inhailers for my asthmatic cat without any problem. When they'd ask, I'd tell 'em. But that was like 15 years ago and I suspect everything at the Border has tightened up.