Beyond that amount, you will need a prescription from a licensed U. These men, who matured when Paz wrote about machismo, were not expected to be faithful, according to Wentzell. And the demand is expected to grow. Summary There are limits to bringing prescriptions purchased at a Mexican pharmacy into the United States. For example, you will be limited to a three-month supply.terrance l. Cancun, Mexico. Level Contributor. 3, posts. 6. Re: Over the Counter Drugs. 12 years ago. Save. In April my DH tried to buy some Amoxicillin to bring back with no . gringolez USA Level Contributor 16 posts 1. Re: Viagra in Cancun 15 years ago Save Not sure how much but have seen it on sale and freely available! Report inappropriate . No need for prescription in Mexico? No need to visit the doctor for refill? No 3 pill limit from insurance company?