Flank Pain After Running: What It Can Mean

Pain at the side of the abdomen or back can follow a sudden increase in pace, distance, hills, or core activity. A stitch may feel sharp and settle when you slow down. Sore muscles are more likely to hurt with twisting, touching, coughing, or a deep breath. Pain that does not behave like a movement-related ache can also come from the urinary system, including kidney stones or a kidney infection.

Stop or reduce the activity, breathe slowly, and avoid another hard run while the pain is active. Gentle movement may help stiffness, but do not force a stretch into sharp pain. Drink normally and note whether the pain returns with exertion, meals, or movement. Seek clinical advice if it persists, keeps recurring, or comes with burning urine, fever, nausea, or a change in urine.

Arrange prompt medical care for severe or worsening flank pain, fever or chills, vomiting, faintness, difficulty passing urine, or visible blood in the urine. Urgent assessment is also appropriate after a significant blow or fall. These features can signal a urinary problem or another condition that should not be attributed to exercise alone.

Ask whether the pattern suggests a muscle problem, a kidney stone, or infection; which examination or urine tests may help; and when it is safe to resume running.