My wife tried Soil Based probiotics (Body Biotics, prescript-assist and AOR-3 are some of the brands). She had had C for a long-time quite bad, and now she is going almost daily. It has only been a few weeks so can’t say for certain it will be a long-term solution or not. Also, be careful with sbo’s if you are immunocompromised. I believe sbo’s are in ferments like sauerkraut as well. And that is cheap and easy to make. It is quite powerful too.