Bladder infection (cystitis) is the most common infection of the lower urinary tract. Bladder infection is usually caused by bacteria that get into the bladder by traveling up the urethra.

Bladder infections are more common in girls and women than in boys and men.

Symptoms of a bladder infection can range from mild to severe, and may include:

• Burning pain with urination (dysuria).
• The frequent need to urinate without being able to pass much urine (frequency).
• Blood in the urine (hematuria).

Symptoms of a bladder infection in children depend on the age of the child. A very young child with a bladder infection may only have a fever. Or he or she may cry when urinating or may vomit. It may be hard to know if the symptoms are a result of urinary problems or another cause.

If untreated, bladder infections can lead to more serious kidney infections that cause fever and lower back (flank) pain, and may damage the kidneys. Bladder infections are treated with antibiotics.