Yes, if left untreated, cystitis can lead to kidney infection.
Yes, women are most likely to have cystitis symptoms, because the opening of the urethra in women is nearer to the anus as compared to men. This puts women at a higher risk of bacterial entry from the intestines into the urinary tract.
Cystitis usually starts to resolve itself after three days.
Cystitis is inflammation of the bladder whereas UTIs are infections of the urinary tract that includes everything from the urethra to the bladder or the kidneys.
Yes, mild cystitis can get resolved on its own within a few days. However, you might need to take antibiotics as well.