A bladder infection can be painful and annoying, and it can become a serious health problem if the infection spreads to your kidneys. Less commonly, cystitis may occur as a reaction to certain drugs, radiation therapy or potential irritants, such as feminine hygiene spray, spermicidal jellies or long-term use of a catheter. Cystitis may also occur as a complication of another illness. The usual treatment for bacterial cystitis is antibiotics. Treatment for other types of cystitis depends on the underlying cause.