20 Cause of Petechiae and What You Need to Know About Them

13. Hemolytic Uremic Syndrome (HUS)

This rare but serious condition typically follows an E. coli infection, particularly in young children. HUS causes red blood cells to break down prematurely, damaging blood vessels and reducing platelet levels. As platelets drop, petechiae may develop, especially on the lower extremities. More alarmingly, HUS also affects kidney function, which can lead to swelling, low urine output, or even acute renal failure. If petechiae appear after a bout of severe diarrhea—especially bloody diarrhea—it’s a red flag. Immediate hospitalization is essential, as supportive care and fluid management can be life-saving in managing HUS.