If paratyphoid fever is left untreated, it can lead to several serious and potentially life-threatening complications as the infection spreads beyond the intestines. One of the most dangerous complications is intestinal bleeding or perforation, which occurs when ulcers form in the lining of the intestines due to prolonged infection and inflammation. These ulcers can erode blood vessels, causing internal bleeding, or even create holes (perforations) in the intestinal wall, allowing bacteria to leak into the abdominal cavity and cause peritonitis, a severe and often fatal infection if not treated promptly. Intestinal bleeding or perforation occurs in about 1% to 3% of untreated cases, but the risk increases the longer treatment is delayed. Other possible complications include sepsis (widespread infection in the bloodstream), meningitis, pneumonia, hepatitis, and inflammation of the heart or kidneys. Early diagnosis and antibiotic therapy significantly reduce these risks, making timely medical care essential for a full recovery and to prevent long-term damage or death.