What’s the difference between... kidney infection and cystitis

A kidney infection (pyelonephritis) is a painful and very serious illness caused by bacteria travelling from your bladder into one or both of your kidneys.

Symptoms of a kidney infection often come on within a few hours. You can feel feverish, shivery, sick (and even vomit) and have a severe pain in your back or side.

If treated promptly, a kidney infection doesn’t cause serious harm but it will make you feel very unwell. If a kidney infection isn’t treated it can get worse and cause permanent kidney damage.

Cystitis is inflammation of the bladder, usually caused by a bladder infection. Mild cases will often get better by themselves within a few days.

However, some people experience episodes of cystitis frequently and may need regular or long-term treatment. They also need a full investigation to see if there’s a predisposing cause of the problem.

Symptoms of cystitis include: pain, burning or stinging when you urinate, needing to urinate more often and urgently than normal, urine that’s dark, cloudy or strong smelling, pain low down in your tummy, and feeling generally unwell, achy, sick and tired.