What should you know about right side flank pain and diarrhea?

Diarrhoea can cause cramping and soreness through the abdomen and side, especially when the bowel is moving frequently. Fluid loss may add weakness, thirst, dizziness, or darker urine. Flank pain and diarrhoea can also occur together by coincidence, or because pain, nausea, or infection affects more than one nearby system. Kidney infection may present with flank pain and fever or urinary symptoms; kidney stones may cause intense waves of pain and nausea, while diarrhoea is not the defining feature. Right-sided abdominal pain that settles in one area deserves attention because the source may not be the bowel.

Take frequent small drinks of water or an oral rehydration solution, particularly after loose stools. Eat light foods as tolerated and avoid alcohol or foods that clearly worsen symptoms. Wash hands carefully and avoid preparing food for others while diarrhoea is active. Note stool frequency, fever, urine output, pain location, and whether the pain moves or becomes constant. Avoid anti-diarrhoeal medicine if you have blood in the stool or significant fever unless a clinician advises it. Contact a healthcare professional if symptoms are not settling or you cannot replace lost fluids.

Seek urgent care for severe or worsening right-sided pain, a rigid or swollen abdomen, repeated vomiting, fainting, confusion, blood or black stool, inability to drink, or very little urine. Fever with flank pain, chills, painful urination, or blood in the urine needs prompt medical review because a urinary condition may be involved. Children, older adults, pregnant people, and people with major health conditions can become dehydrated sooner and should seek advice early.

Could the diarrhoea explain the pain, or does its location suggest another source? How can I replace fluids safely? Should I provide a stool or urine sample? Which medicines should I avoid?