A stitch in your side is a sharp, localized pain that strikes just below your ribs during physical activity. It typically hits on the right side, though it can appear anywhere across the abdomen. Doctors call it exercise-related transient abdominal pain (ETAP), and while it can be intense enough to force you to stop mid-run, it’s almost always harmless and resolves on its own within minutes.
Why It Happens
Despite how common side stitches are, researchers still aren’t entirely sure what causes them. Several competing theories exist, and the real answer may involve more than one mechanism at once.
The leading explanation points to irritation of the parietal peritoneum, a thin membrane that lines the inside of your abdominal wall and the underside of your diaphragm. During vigorous movement, friction or pressure changes along this membrane may trigger the characteristic sharp, well-localized pain. This theory does the best job of explaining why a stitch feels so pinpointed, why you can press on the exact spot, and why it eases quickly once you stop moving.
An older theory focuses on the ligaments that suspend your stomach, liver, and intestines from the diaphragm. Repetitive bouncing or jolting tugs on these ligaments, creating strain. This would explain why running and horseback riding produce more stitches than cycling or swimming, and why eating a large meal beforehand makes a stitch more likely: a full stomach is heavier, pulling harder on those attachments with every stride.
What a Stitch Feels Like
Most people describe it as a sharp or stabbing sensation concentrated in one spot, usually just under the ribcage on the right side. In milder cases it can feel more like a dull ache or cramping. The pain tends to worsen if you keep going at the same intensity, and it often fades within a few minutes of slowing down or stopping. Some people also feel a pulling sensation in the tip of one shoulder, which makes sense anatomically because the diaphragm and shoulder share some of the same nerve pathways.
Who Gets Them
Side stitches are extremely common, especially in activities that involve repetitive torso movement. Runners, swimmers, and horse riders report them frequently. Younger athletes tend to experience them more than older ones, and beginners are more susceptible than trained athletes. That said, even elite runners get stitches during races. Fitness level helps reduce the frequency, but it doesn’t make you immune.
Common Triggers
Eating or drinking too close to exercise is one of the most reliable triggers. A full stomach increases the weight pulling on your abdominal ligaments, and sugary or highly concentrated drinks appear to be worse offenders than plain water. The general guideline is to avoid large meals for at least two hours before intense exercise and to sip fluids in small amounts rather than gulping them down.
Starting out too fast without a proper warm-up also increases your chances. Shallow, rapid breathing seems to play a role too, possibly because it limits the full range of diaphragm movement and creates more tension in the surrounding tissues. Cold weather, poor posture, and exercising at an unfamiliar intensity can all contribute.
How to Stop a Stitch Mid-Exercise
The fastest fix is simply slowing down. Dropping your pace or walking for 30 to 60 seconds allows the muscles around your chest and abdomen to relax, and the pain often fades quickly.
If you don’t want to stop completely, try changing your breathing pattern. Take a slow, deep breath in, then exhale fully and forcefully. Repeat this several times. Deep breathing helps relax the diaphragm and can relieve the tension that contributes to the pain.
Stretching the affected side also works well. Raise the arm on the same side as the stitch above your head and lean gently away from the painful side, holding the stretch for a few seconds. This elongates the cramping muscles and often brings noticeable relief.
Another option is to press your fingers firmly but gently into the painful spot while bending forward slightly at the waist. The combination of pressure and forward flexion can ease the spasm. Some runners find that exhaling forcefully each time their foot on the opposite side of the stitch hits the ground helps break the cycle, possibly by shifting the timing of impact forces on the abdominal organs.
How to Prevent Stitches
Timing your meals is the single most practical prevention strategy. Allow at least one to two hours after a meal before running or doing any high-impact activity. If you need to eat closer to your workout, stick to small, low-fiber, low-fat snacks that leave the stomach quickly. Avoid fruit juice, soda, and other concentrated sugary drinks right before exercise. Plain water, sipped gradually, is your safest bet.
Warming up properly also helps. Spend five to ten minutes at a lower intensity before ramping up your effort. This gives your diaphragm and abdominal muscles time to adjust to the increased demand. Practicing deep, rhythmic “belly breathing” during your warm-up can train the diaphragm to move through its full range, reducing the likelihood of a stitch later.
Strengthening your core over time appears to lower stitch frequency as well. A stronger abdominal wall provides better support for the internal organs and may reduce the mechanical irritation that triggers the pain. This is consistent with the observation that trained athletes report fewer stitches than beginners.
When Side Pain Is Something Else
A typical side stitch is tied directly to exercise, stays in one spot below the ribs, and goes away within minutes of resting. If your pain doesn’t follow that pattern, it may be worth paying attention. Pain that persists long after you’ve stopped exercising, worsens over hours, or is accompanied by fever, nausea, vomiting, or changes in bowel habits could point to something unrelated to exercise, such as a gastrointestinal issue, a kidney stone, or in rare cases, a problem with the appendix or spleen.
Sharp chest pain, difficulty breathing that doesn’t improve with rest, or pain that radiates into your jaw or left arm during exercise are not stitches. These symptoms warrant immediate medical attention. The key distinction is that a true side stitch is predictable, brief, and completely resolves once you ease up on activity.