Pain on the left side of your body can signal various issues, from minor muscle strains to serious medical emergencies. Common causes include injury or infection affecting organs such as the heart, spleen, left lung, kidney, or pancreas. While some pain resolves on its own, other cases require immediate medical attention. It is best to contact a doctor for an accurate diagnosis, as they may perform a physical exam and order tests to confirm the cause.

An enlarged or damaged spleen can cause pain behind the left ribs, tenderness, dizziness, and a rapid heart rate. A ruptured spleen is a medical emergency. Diverticulitis, where small pouches in the colon become inflamed, typically causes sudden or worsening pain in the lower left abdomen along with fever, nausea, or changes in bowel habits. A heart attack may present as pain in one or both arms, chest discomfort, shortness of breath, cold sweat, or lightheadedness.

Sciatica, often caused by a herniated disk, can create a “knife-like” pain or pins-and-needles sensation on one side of the body. Gas buildup in the colon may cause left-sided pain, often relieved by dietary changes. Strains and sprains from injury can also produce localized pain, swelling, and difficulty moving. The RICE method—rest, ice, compression, and elevation—is recommended for recovery.

For women, a ruptured ovarian cyst can cause sudden severe lower abdominal pain on one side. For men, testicular torsion is a medical emergency requiring surgery within hours. Kidney infections cause back or side pain, fever, and painful urination, and can lead to sepsis if untreated. Seek urgent care for heart attack symptoms, kidney infection, testicular torsion, diverticulitis, or a suspected injured spleen.