A side stitch is a sharp, localized pain in your abdomen that strikes during physical activity, most often along the sides of your mid-abdomen. It’s harmless, but it can be intense enough to slow you down or force you to stop entirely. The medical name is exercise-related transient abdominal pain (ETAP), and it’s one of the most common complaints among runners and other endurance athletes.
What It Feels Like
The sensation depends on how severe it is. When a side stitch hits hard, most people describe it as sharp or stabbing. Milder episodes feel more like cramping, aching, or a pulling sensation. The pain is well localized, meaning you can usually point to a specific spot rather than feeling a vague discomfort across your belly. While it most commonly strikes the sides of the mid-abdomen, it can technically show up in any region of the abdomen.
A side stitch typically fades within minutes of slowing down or stopping. That’s the key feature that separates it from something more serious: it’s directly tied to exercise and it goes away when the activity stops.
Why It Happens
Despite how common side stitches are, researchers still aren’t entirely sure what causes them. The leading theories focus on mechanical stress inside your torso during repetitive movement.
One explanation centers on the ligaments that connect your internal organs to your diaphragm. When you’re running, the constant jolting motion tugs on these ligaments while your breathing is already laboring. That combination of impact and heavy breathing strains the connective tissue, potentially causing the spasms you feel as a sharp stitch. Another theory involves irritation of the membrane lining your abdominal cavity, which may get aggravated by friction or changes in fluid dynamics during exercise.
Neither theory has been definitively proven, and the reality may involve both mechanisms or vary from person to person. What is clear is that certain conditions make a stitch far more likely to occur.
Who Gets Side Stitches
In a study of participants in Sydney’s City to Surf community run, 27% of respondents reported experiencing a side stitch during the event. Runners were hit more often than walkers: 30% versus 16%. That makes sense given the greater impact forces and breathing demands of running compared to walking.
Age plays a role, too. The frequency of side stitches decreases as people get older. Younger athletes report them significantly more often, which may relate to changes in the elasticity of connective tissue or simply to decades of the body adapting to exercise. Fitness level doesn’t seem to make you immune, though. Even well-trained athletes get them.
Food, Drink, and Timing
What you eat and drink before exercise is one of the biggest controllable risk factors. Eating a heavy or high-fat meal less than one to two hours before a run is a well-known trigger. The same goes for drinking beverages high in sugar or concentrated carbohydrates right before or during exercise. These hypertonic drinks (sports drinks with high sugar content, fruit juices, sodas) slow gastric emptying, meaning your stomach stays fuller longer and increases pressure inside your abdomen.
The practical guideline is straightforward: wait two to three hours after a full meal before exercising, and stick to small sips of water or low-sugar fluids during activity. If you use sports drinks, choose ones that aren’t heavily concentrated, and avoid high-calorie, high-fat, or high-glycemic foods in the few hours leading up to a workout.
How to Get Rid of One Mid-Run
Most runners develop their own tricks over time, but a few approaches work reliably. Slowing your pace is the most effective immediate response. If that’s not enough, try pressing your fingers gently into the painful spot while bending slightly forward. Some people find relief by changing their breathing pattern: exhale as the foot on the opposite side of the pain strikes the ground. This shifts the mechanical stress on your diaphragm’s ligaments.
If the stitch is severe, stop and walk. It will almost always resolve within a few minutes. Pushing through an intense stitch rarely makes it worse in a medical sense, but it’s deeply unpleasant and can compromise your form, which increases your risk of other injuries.
Reducing Them Over Time
Side stitches tend to become less frequent as your body adapts to a particular type of exercise. If you’re new to running, expect them to show up more often in the first few weeks and gradually taper off.
Core strength appears to make a measurable difference. A 2014 study of 50 runners found that those with stronger trunk muscles experienced fewer side stitches. This makes sense given the ligament-strain theory: a more stable core provides better support for the structures inside your abdomen during repetitive impact. Exercises like planks, dead bugs, and rotational movements that build deep abdominal and oblique strength are worth incorporating into your routine.
Warming up properly also helps. Jumping straight into high-intensity effort without easing into it increases your risk. A gradual warm-up gives your breathing and internal organs time to adjust to the increased demand.
When the Pain Isn’t a Stitch
A true side stitch is tied to exercise and resolves quickly once you stop. If your abdominal pain persists after you’ve cooled down, migrates to a different location, or comes with fever, vomiting, or worsening tenderness, something else is going on. Appendicitis, for instance, can start as vague abdominal discomfort before localizing to the lower right side, and it doesn’t go away with rest. Kidney stones, ovarian cysts, and bowel conditions can also mimic exercise-related pain.
The distinguishing feature of a side stitch is its predictable pattern: it appears during activity, stays in one spot, and disappears with rest. Pain that breaks any of those rules deserves medical attention.