When your side hurts while you run, it’s usually a benign “side stitch” (exercise-related transient abdominal pain), but if the pain is severe, sudden, or associated with other worrying symptoms, you should get medical help urgently.

Quick Scoop

What’s probably going on

Most runners’ side pain is a side stitch , a sharp or crampy pain just under the ribs, often on the right side.

Experts think it often comes from:

  • Spasm or fatigue of the diaphragm (the breathing muscle under your lungs).
  • Strain on ligaments that connect your organs to the diaphragm during the jolting motion of running.
  • Irritation of the inner abdominal lining (parietal peritoneum) in some people.
  • Poor posture or hunching, which increases stress on your spine and torso.
  • Doing too much, too fast if you’re newer to running or ramping up quickly.

Other causes of “side pain when I run” can include muscle strain, gas/bloating, or, less commonly, more serious problems like gallbladder, appendix, or heart issues.

Those more serious causes are usually accompanied by red-flag symptoms (see below).

Common triggers people report

  • Eating or drinking a large meal too soon before running.
  • Dehydration or lots of sugary drinks before/during exercise.
  • Shallow, fast, upper‑chest breathing instead of steady deeper breaths.
  • Weak core muscles and poor running form (slouching, excessive twisting).
  • Sudden increases in pace, distance, or hills.

Things you can try during a run

  • Slow down or briefly walk while you work on your breathing.
  • Switch to deep, controlled belly breathing (inhale through nose, exhale through mouth).
  • Time your exhale to the opposite foot of the painful side (if right side hurts, exhale as your left foot lands).
  • Gently press your fingers into the painful spot and bend slightly forward while exhaling.
  • If it doesn’t ease in a few minutes, stop and rest; persistent pain is a sign to back off.

How to reduce the chances next time

  • Avoid big meals for 2–3 hours before running; keep pre‑run snacks small and simple.
  • Sip fluids instead of chugging large amounts right before you head out.
  • Warm up gradually rather than sprinting from the start.
  • Work on posture and core strength (planks, side planks, gentle strength work several times a week).
  • Practice relaxed, rhythmic breathing on easy walks or jogs so it’s automatic when you run.

When side pain might be more serious

Get urgent medical care (ER/urgent care, or call emergency services) if your side pain:

  • Is sudden and severe, or “the worst pain you’ve ever felt.”
  • Comes with chest pain, shortness of breath at rest, jaw/arm pain, or feeling faint.
  • Is accompanied by fever, vomiting, blood in stool or urine, or pain that moves to the lower right abdomen (possible appendix).
  • Does not improve after stopping running and resting, or keeps getting worse over hours.

And arrange a non‑urgent doctor visit if:

  • The pain repeatedly returns in the same spot even with good warm‑up, pacing, and food timing.
  • You have a history of gallbladder or kidney problems, or other chronic conditions.

Information gathered from public forums or data available on the internet and portrayed here.