Peritonitis is an inflammation of the peritoneum — the thin tissue lining the inner wall of your abdomen. It most commonly results from a bacterial or fungal infection and can develop rapidly in people with liver disease, recent abdominal surgery, or a ruptured organ. Recognizing peritonitis symptoms early is critical because delayed treatment can lead to sepsis and organ failure, making this a genuine medical emergency.
1. Severe Abdominal Pain
The hallmark of peritonitis is intense, often unbearable abdominal pain. It may begin as a dull ache near the source of infection and quickly spread across the entire belly. Research indicates that secondary peritonitis often starts with sharp, localized pain that becomes diffuse as the infection spreads to the broader peritoneal cavity. The pain typically worsens with any movement, coughing, or even light touch. Unlike ordinary stomach cramps, this pain does not come and go — it tends to be constant and escalating. If you experience sudden, severe abdominal pain that doesn’t ease within minutes, treat it as an emergency and seek immediate medical care.
2. Fever and Chills
A rising fever paired with shaking chills is one of the most reliable peritonitis symptoms. Your body temperature may spike above 101°F (38.3°C) as the immune system fights the spreading infection. Clinical evidence shows that fever and chills are among the earliest and most consistent signs of septic peritonitis, often appearing before other symptoms fully develop. This fever can fluctuate and may be accompanied by night sweats. If a high fever appears alongside stomach pain, do not attempt to manage it at home with over-the-counter medications alone — contact a healthcare professional right away.
3. Abdominal Tenderness and Rigidity
When the peritoneum becomes inflamed, even gentle pressure on the abdomen triggers significant pain. Doctors refer to this as abdominal tenderness, and it is a key diagnostic clue. In more advanced cases, the abdominal muscles involuntarily tighten into a board-like rigidity. This rigidity is your body’s protective reflex, guarding the inflamed tissues beneath. Studies suggest that diffuse abdominal tenderness with wall rigidity strongly points toward peritonitis rather than a less serious gastrointestinal issue. If your belly feels unusually hard and painful to the touch, this warrants urgent medical evaluation.
4. Rebound Tenderness
Rebound tenderness is a specific clinical sign that healthcare providers check during a physical exam. It occurs when pain intensifies not during pressure on the abdomen, but when that pressure is suddenly released. Research indicates that rebound tenderness, along with guarding, is a hallmark finding during examination of patients with primary peritonitis. This symptom reflects irritation of the peritoneal lining itself. You can notice it at home if pressing gently on your belly and then letting go causes a sharp spike in pain. This sign alone is considered a red flag for peritoneal inflammation and should prompt an emergency room visit.
5. Nausea and Vomiting
As infection takes hold in the abdominal cavity, the digestive system often responds with persistent nausea and vomiting. These symptoms develop because the inflamed peritoneum sits close to the stomach and intestines, disrupting normal gut function. Vomiting may start mild but can become forceful and frequent as the condition progresses. The combination of vomiting and inability to keep fluids down also raises the risk of dangerous dehydration. If nausea and vomiting accompany abdominal pain and fever, do not dismiss them as a simple stomach bug — seek medical attention promptly to rule out peritonitis.
6. Bloating and Abdominal Distension
Many people with peritonitis notice that their abdomen looks and feels visibly swollen. This bloating occurs because inflammation causes fluid to accumulate in the peritoneal cavity, a condition called ascites. Gas may also build up as the intestines slow down or stop moving properly. The distension can make it difficult to breathe comfortably, especially when lying flat. Unlike the occasional bloating from a heavy meal, this swelling is persistent and often painful. If your abdomen rapidly increases in size alongside other warning signs, it is important to get evaluated by a doctor without delay.
7. Diarrhea or Inability to Pass Stool
Peritonitis can push the bowels in two opposite directions. Some patients develop watery diarrhea as the body attempts to flush out infection and excess fluid. Others experience a complete halt in bowel movements, a condition known as ileus, where the intestines essentially stop contracting. Clinical evidence shows that both diarrhea and ileus are recognized signs of peritoneal infection, depending on the stage and severity. This unpredictable bowel disruption often accompanies other peritonitis symptoms like pain and bloating. Pay attention to any sudden, dramatic change in bowel habits that coincides with abdominal discomfort.
8. Low Blood Pressure and Rapid Heart Rate
As peritonitis progresses, the infection can affect your cardiovascular system. Blood pressure may drop significantly while the heart races to compensate, a combination that signals the body is under serious stress. These changes happen because the infection triggers widespread inflammation, causing blood vessels to dilate and fluid to shift out of the bloodstream. You might feel lightheaded, dizzy, or faint when standing up. Studies note that low blood pressure is a particularly concerning nonspecific sign in peritonitis patients with underlying liver disease. If you notice a racing pulse alongside belly pain, call for emergency help immediately.
9. Confusion or Altered Mental Status
One of the more alarming peritonitis symptoms is a sudden change in mental clarity. Patients may become confused, disoriented, or unusually drowsy as toxins from the infection enter the bloodstream. This is especially common in older adults and people with cirrhosis, where the liver’s reduced ability to clear toxins compounds the problem. Research suggests that confusion or worsening mental status in cirrhosis patients can be a presenting sign of spontaneous bacterial peritonitis, even before abdominal pain becomes obvious. Family members often notice these cognitive changes first. Any sudden confusion paired with physical symptoms should be treated as a medical emergency.
10. Decreased Urine Output
When peritonitis becomes severe, the kidneys may begin to struggle. Decreased urine output is a warning sign that infection-related inflammation is impairing blood flow to the kidneys, potentially leading to acute kidney injury. You might notice that you are urinating far less than usual despite drinking normal amounts of fluid. The urine may also appear darker than usual. Clinical evidence links worsening renal function to advancing peritonitis, particularly in patients who already have compromised liver function. Monitoring urine output at home can provide a valuable early clue, so alert your doctor immediately if you notice a significant decline.
Peritonitis is a time-sensitive medical emergency, and recognizing these symptoms early can genuinely save your life. If you or someone you know experiences a combination of severe abdominal pain, fever, and any of the other warning signs listed above, do not wait — call emergency services or go to the nearest emergency room. Quick diagnosis and treatment with antibiotics or surgery remain the most effective ways to prevent life-threatening complications.
Medical Disclaimer: This article is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional before making health decisions.
