Left Side Pain
Lower left pain is often caused by diverticulitis or IBS. Upper left pain may result from pancreatitis, gastritis, stomach ulcers, an enlarged spleen, kidney issues, heart problems like angina or pericarditis, or lung conditions such as pneumonia.

Right Side Pain
Lower right pain might indicate appendicitis. Upper right pain can involve the liver (hepatitis or cancer), gallbladder (gallstones or inflammation), right kidney, or a duodenal ulcer.

When to See a Doctor
Consult a doctor if the pain is severe, persistent, or recurring—especially if accompanied by vomiting, dehydration, blood in stool or vomit, breathing issues, jaundice, pregnancy, or unexplained weight loss.

Seek emergency care for sudden, intense pain or symptoms that worsen quickly.