I've got major high blood pressure, I convinced my physician to give me a back-up 90 day supply. (I normally get 90 day refills) Which I keep in my BOV. I rotate them out and put the "fresh perscription" in my truck and use the "old" batch. I know, before everyone goes off at me (my doctor already did) but the way I look at it 90 day old meds are better than none. So far I haven't seen any reduction in potency but, the potential exists. Anyway If SHTF I can go for 90 days at least.