Peritonitis: symptoms, causes, treatment and when it is an emergency

The NHS lists the symptoms of peritonitis as tummy pain, a very high temperature or feeling hot, cold or shivery, a rapid heartbeat (your heart beating more quickly than normal) and not being able to pee or peeing much less than normal.

You might also have a lack of appetite and feel or be sick, and a swollen tummy. If you are having kidney dialysis treatment, the NHS says the fluid in the collection bag might look cloudier than usual or contain white flecks.

The NHS says to ask for an urgent GP appointment or get help from NHS 111 if you have symptoms of peritonitis. Serious complications like sepsis can happen if the infection spreads, and the NHS says that left untreated peritonitis can become life threatening.

Sepsis is a serious reaction to an infection that can be life-threatening and develops very quickly. The NHS says to call 999 or go to A&E for an adult who is breathing very fast, is confused or has slurred speech, has blue, pale or blotchy skin, has a very high or very low temperature or is shivery, or has a rash that does not fade when pressed. Do not drive yourself to A&E.

For babies and children under 5, the NHS lists signs including breathing very fast or having difficulty breathing, blue, grey or pale skin, a rash that does not fade, being very sleepy or difficult to wake, and not having a pee for the last 12 hours.

The peritoneum is the lining of the tummy. The NHS explains that it covers internal organs like the kidneys, liver and bowel. If the lining becomes infected and you get peritonitis, the internal organs it covers can also be damaged.

The NHS says peritonitis most often happens because of another problem in the abdomen. Other NHS pages link specific conditions with peritonitis: a burst appendix, a hole in the stomach from an ulcer, and a perforation of the bowel in diverticulitis.

The NHS says that if you are diagnosed with peritonitis, you will need treatment in hospital to get rid of the infection. Treatment usually involves antibiotics given into a vein (intravenously). If you have regular kidney dialysis, your doctor might discuss a different way of doing it until the peritonitis has been treated.

It can be difficult to digest food with peritonitis. A feeding tube may be passed into your stomach through the nose or placed inside the stomach using keyhole surgery. If a feeding tube cannot be used, liquid nutrients can be given directly into a vein.

If part of your stomach lining has been seriously damaged by infection, the NHS says you may need surgery to remove it. Sometimes pus-filled swellings (abscesses) develop in the lining and need to be drained with a needle under local anaesthetic.

You might also need an operation to deal with the cause of the peritonitis. For example, a burst appendix will need to be removed.

Recovery depends on the cause and how unwell you were. If sepsis develops, the NHS says treatment includes antibiotics, oxygen and fluids into a vein, sometimes in a specialist care unit, and that it can take weeks or months to recover.

The NHS suggests being patient, getting enough sleep (adults usually need 7 to 9 hours), eating a healthy balanced diet with smaller, more frequent meals if appetite is reduced, exercising regularly but building up slowly, keeping a diary of your progress and talking to a partner or friend, or contacting The UK Sepsis Trust.

The NHS peritonitis page does not give separate advice for children. Because infection can make a child seriously unwell quickly, use the NHS sepsis signs above, and seek urgent help for a child with tummy pain together with a high temperature, being sick, a swollen tummy or unusual sleepiness.

On the NHS, suspected peritonitis is assessed urgently through NHS 111, a GP, or an emergency department, with blood tests and scans in hospital and treatment on a surgical or medical ward. People on peritoneal dialysis are usually looked after by their renal team.

Because the NHS describes peritonitis as needing urgent medical attention and treatment in hospital, the route to take if you have severe tummy pain with fever is the urgent one described above, rather than waiting for a routine appointment.