Side Stitch While Running: Why It Happens and How to Fix It

A side stitch while running is that sudden, sharp pain below your ribs that hits mid-run and forces you to slow down or stop altogether. Nearly every runner has dealt with one at some point, especially beginners. The good news is that it is not harmful, has very specific causes, and can be both prevented and eliminated on the go with a few simple techniques covered in this article.

What is a side stitch (and why it happens when you run)

A side stitch, known medically as exercise-related transient abdominal pain (ETAP), is a localized stabbing sensation in the abdomen — usually on the right side, just below the ribs — that occurs during activities involving repetitive vertical movement like running.

Despite being one of the most common complaints among runners, its exact cause is still debated by researchers. The most widely accepted theory points to irritation of the peritoneum, the membrane that lines the abdominal cavity. While running, the constant bouncing causes the internal organs to pull on the ligaments connecting them to the diaphragm, producing that characteristic stabbing pain.

A complementary explanation involves a diaphragm spasm: when breathing is shallow or uncoordinated, the diaphragm does not receive enough oxygen and contracts irregularly, generating pain. This is why your breathing technique while running plays such an important role in preventing side stitches.

4 main causes of side stitches

While the exact mechanism is not fully resolved, four factors significantly increase the likelihood of getting a side stitch during your run:

1. Eating or drinking too much before running

This is the most common trigger. When your stomach is full or still digesting, it takes up more space and weighs more. That extra weight pulls on the ligaments connecting the stomach to the diaphragm as you bounce with each stride. Sugary drinks and high-fat foods before a run are particularly problematic. Check out our nutrition guide for runners to time your meals better.

2. Shallow or erratic breathing

Breathing rapidly and shallowly — using only the upper chest — prevents the diaphragm from moving properly. This creates tension in the respiratory muscles and makes spasms more likely. Runners who practice deep abdominal breathing experience far fewer side stitches.

3. Starting too fast without warming up

Going all out from the very first step is a recipe for a side stitch. Your body needs a few minutes to redirect blood flow away from internal organs and toward the working muscles. If you skip the warm-up, the diaphragm and abdominal organs experience an abrupt shift that favors the onset of pain.

4. Low fitness level or weak core

Beginner runners and those with weak abdominal muscles are more prone to side stitches. A strong core stabilizes the internal organs and reduces the excessive movement that causes peritoneal irritation. This is one of the most common beginner running mistakes: focusing only on mileage and neglecting complementary strength work.

How to get rid of it instantly (3 techniques)

The side stitch has struck and you are mid-run. You do not have to stop completely. Try these techniques in order of effectiveness:

Technique 1: Direct pressure + controlled breathing

Slow your pace slightly. Place your hand on the painful spot and press firmly while leaning your torso slightly toward that side. At the same time, breathe deeply: inhale through your nose for 3 seconds, filling your belly (not your chest), and exhale through your mouth for 4 seconds, emptying completely. Repeat for 30-60 seconds. In most cases, the pain will fade away.

Technique 2: Exhale when the opposite foot lands

If the pain is on your right side, exhale forcefully every time your left foot hits the ground (and vice versa). This shifts the pressure dynamics inside the abdomen and reduces the tension on the ligaments of the affected side. It is subtle, but it works surprisingly well once you find the rhythm.

Technique 3: Stop, stretch and restart

If the first two techniques do not work, stop for 30 seconds. Raise the arm on the painful side above your head and stretch laterally toward the opposite side. This opens the ribs and relaxes the diaphragm. Take 3-4 deep breaths in that position. Then resume running at a gentler pace and gradually increase speed.

How to prevent it (5 tips)

Better than knowing how to fix a stitch is preventing it from happening in the first place. These five habits eliminate side stitches for most runners:

1. Respect digestion times

Leave at least 2 hours between a full meal and your run. If you need to eat closer to training time, go for a light snack (a banana, a couple of crackers, some fruit) and wait 30-45 minutes. Avoid fatty foods, high-fiber meals, and carbonated drinks before running.

2. Always warm up before running

Spend 5-10 minutes on a gradual warm-up: brisk walking, easy jogging and a few mobility drills. This prepares the diaphragm, redistributes blood flow and dramatically reduces the chance of a side stitch. Check our warm-up guide for runners for a complete routine.

3. Train your belly breathing

Practice diaphragmatic breathing away from your runs: lie on your back, place one hand on your chest and the other on your belly. When you inhale, only the belly hand should rise. Do this for 5 minutes daily and your body will automate the pattern while running. We have a full breathing guide for runners with specific drills.

4. Strengthen your core

Strong abdominal muscles stabilize the internal organs and reduce the movement that causes peritoneal irritation. You do not need anything fancy: planks (3 x 30 seconds), dead bugs (3 x 10 per side) and bird dogs (3 x 10 per side), three times a week, make a massive difference.

5. Build intensity gradually

Both within each run and across your weekly plan. Always start at a comfortable pace and build from there. Do not increase weekly mileage by more than 10%. Respecting progression prevents not only side stitches but also more serious injuries.

When to worry

A side stitch is annoying but harmless. However, there are situations where abdominal pain during a run warrants medical attention:

• The pain does not go away after you stop running and rest for 10-15 minutes
• It spreads to the chest, shoulder or left arm (could indicate a cardiac issue)
• It comes with nausea, dizziness or disproportionate difficulty breathing
• It appears consistently on every run despite applying all prevention strategies
• The pain is in the lower abdomen rather than the side (could have a gastrointestinal or pelvic origin)

In these cases, see your doctor to rule out digestive, musculoskeletal or, in rare cases, cardiac problems. But to reassure you: in 99% of cases, a side stitch is simply a temporary nuisance that you can manage with the techniques described above.

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