The problem with that is the medicine expires, sometimes fairly quickly. You'd have to show up with symptoms every six(??) months to get a new script.

Ya know, the Army did a study on the expiration dates and found the medicines were effective many years after the expiration dates. And none of them degraded and became something poisonous. So I'd have no problem taking Tamiflu a couple of years after the expiration dates. I'm using antibiotic ointments many years after the expiration date and they're still effective. I've used up pills after the expiration date and they still cleared my sinuses, and stopped infections. That's just me though. But - worth a read

SNIP Solid dosage forms, such as tablets and capsules, appear to be most stable past their expiration date. Drugs that exist in solution or as a reconstituted suspension, and that require refrigeration (such as amoxicillin suspension), may not have the required potency if used when outdated. Loss of potency can be a major health concern, especially when treating an infection with an antibiotic. In addition, antibiotic resistance may occur with sub-potent medications. Drugs that exist in solution, especially injectable drugs, should be discarded if the product forms a precipitant or looks cloudy or discolored. SNIP

ncbi.nlm.nih.gov: Drug expiry debate: the myth and the reality

But if you read Eric, you can ask for a prophylatic prescription.

Expats would buy antibiotics for Chickens at the agrivet, try and figure the dosage and take that. I used to get amoxicillin before a trip - helped one time because I got some bad food and the doc didn't prescribe. I took the complete round because my symptoms were still there, knocked it right out.