Drink a glass of cranberry juice every day. I mix it with lemonade as I'm not keen on the taste. I had such a recurrence of cystitis, I damaged a kidney when it turned to pyelonephritis. There is no way to describe the excruciating pain.
The cranberry puts a lining on your bladder which the germs can't stick to and they are flushed out when you empty your bladder.
Since drinking cranberry every day, I haven't had cystitis for 15 years. Bliss!
Update: I'm peed off (pardon the punt) but last day of antibiotics & still feel as though my bladder is going to busrt! Doctor just rang me & says my water sample was fine & he cannot prescribe me a different antibiotic! I have to wait now for hospital appointment for ultrasound!