As to how long it lasts, it varies from person to person, but it can be 2 months or even up to 6 months.It will take longer for the body to right itself, the longer you were taking the medication, so you should be ok in a few weeks if you only took it for a couple of weeks.hen I'd collected a prescription for PPI's the doctor told me that if I needed long term medication Ranitidine was now the drug of choice for chronic sufferers due to side effects of PPI's, so I couldn't reconcile that statement with the warning on the OTC packet. Thanks again.