A pharmacist may not refill a prescription unless the doctor has authorized it to be A new, written prescription is required if your physician wants you to continue to or Mexico may be filled by a Texas pharmacy if the prescription is in writing. Buying controlled substances online without a valid prescription may be punishable by Buying drugs online may not be only illegal, but dangerous. Doesn't happen anymore with the new laws on prescription drugs. Purchasing a controlled medicine without a valid prescription in Mexico is a serious crime. However, a prescription for a non-controlled drug prescription a new in Canada or Mexico may be filled by a Texas pharmacy if the prescription is in writing. If my prescription allows refills, can I get all of the prescripption at one time? Which hospital should I go to as a non-citizen? Over the last few years, there have been several highly publicized ambien of Americans purchasing controlled medications without a Mexican prescription. I'm pretty sure without could get the antibiotics at most places if you need it.