Just drink water constantly. I drink litres and litres a day because i worry about getting it all the time. The day i lost my virginity i got cystitus, and was too embarrassed to talk about it. I ended up having to go to hospital and on a 3 month course of medication because id ruined the lining of the urethra, bladder and kidneys... If you just go on antibiotics to get rid of it, make sure you stay clean and dont have sex, if thats whats causing it... then after its cleared up just drink lots of water all the time. If it is sex thats causing it, make sure you go for a wee before and after. Haha, i apologise if it isnt sex related!