That sharp, stabbing pain in your side during a run is called a side stitch, and it’s one of the most common complaints among runners. Formally known as exercise-related transient abdominal pain (ETAP), it typically hits just below the ribcage, more often on the right side, and can range from a dull ache to a cramp intense enough to force you to stop. In a study of 965 athletes, 69% of runners reported experiencing it.
What Causes a Side Stitch
Despite how universal the experience is, scientists still don’t have a single confirmed explanation. Three competing theories have held up over decades of research. The first is that your diaphragm, the large muscle responsible for breathing, temporarily loses adequate blood flow during intense exercise. The second is that the repetitive jolting of running tugs on ligaments connecting your abdominal organs to the diaphragm. The third, and currently most supported, is that the inner lining of your abdominal cavity becomes irritated from friction as your organs shift during movement.
That last theory helps explain why side stitches aren’t exclusive to running. Swimming actually triggers them more often, affecting 75% of swimmers in the same large athlete survey. Horse riding (62%), aerobics (52%), and basketball (47%) all provoke them at notable rates, while cycling, which involves far less vertical bouncing, only causes them in about 32% of athletes.
Why What You Drink Matters More Than You Think
One of the strongest and most consistent findings in side stitch research is the role of high-sugar drinks. Beverages with high sugar concentrations, like fruit juice, are significantly more likely to trigger a stitch than water or sports drinks. In one study, 83% of subjects developed side pain after drinking a high-sugar solution before running, compared to 70% with lower-sugar options. Fruit juice with about 11% carbohydrate content was specifically identified as more provocative than water or standard sports drinks, and it also caused more bloating.
A separate treadmill study found that an isotonic sports drink (one that matches your body’s natural fluid concentration) actually caused fewer symptoms than plain water, while a high-sugar drink was worse than both. The practical takeaway: if you’re prone to side stitches, skip the juice or soda before a run. A standard sports drink or plain water is a safer choice.
Food Timing and Your Pre-Run Meal
Eating too close to a run is one of the most reliable ways to bring on a stitch. The general guideline backed by research is to avoid large volumes of food and drink for at least two hours before exercise. A full stomach increases the weight pulling on those abdominal ligaments and leaves more material in your gut to slosh around.
That said, skipping meals entirely isn’t the answer either. Research comparing athletes who ate three hours before exercise versus six hours before found that the three-hour group actually performed better, lasting longer before exhaustion. So the sweet spot for most runners is a moderate meal about three hours out: enough to fuel the run without weighing down your stomach. If you need something closer to go time, keep it small, low in fat, and low in fiber.
How to Stop a Stitch Mid-Run
When a side stitch hits, you don’t necessarily have to stop completely. The most widely recommended technique is to slow your pace and focus on deep, controlled breathing. Breathe out forcefully through pursed lips while pressing your hand into the painful spot. Some runners find relief by timing their exhale to the foot strike on the opposite side of the pain. If the stitch is on your right side, for example, exhale each time your left foot hits the ground. This may reduce the repetitive tugging on the painful side.
Bending forward slightly at the waist while pressing into the stitch can also help. If none of that works, walking for 30 to 60 seconds with slow, deep breaths usually resolves it. Side stitches are transient by definition. They go away once the irritation settles, and they almost never cause lasting harm.
Who Gets Side Stitches Most Often
Younger athletes report side stitches far more frequently than older ones, and researchers aren’t entirely sure why. It may be that the abdominal lining becomes less sensitive with age, or that experienced athletes gradually learn eating and pacing habits that minimize the problem. Newer runners are also more prone, likely because they tend to start at intensities their bodies aren’t conditioned for, breathing harder and jostling their torso more than someone with a trained, efficient stride.
How to Prevent Side Stitches
Prevention comes down to a few consistent habits:
- Time your meals. Finish eating at least two to three hours before running, and keep pre-run meals moderate in size.
- Choose your drinks carefully. Avoid fruit juice, soda, or any high-sugar beverage before exercise. Water or a standard sports drink is less likely to cause problems.
- Warm up gradually. Jumping straight into a hard pace increases the odds of a stitch. Start with a few minutes of easy jogging or brisk walking.
- Strengthen your core. A stable trunk reduces the amount of internal shifting during each stride. Planks, side planks, and rotational exercises all help.
- Work on your breathing. Practice rhythmic, diaphragmatic breathing during easy runs so it becomes automatic at higher intensities.
When Side Pain Signals Something Else
A typical side stitch fades within minutes of slowing down or stopping, and it leaves no lingering symptoms. If you experience abdominal pain during exercise that persists well after you’ve cooled down, recurs in the same spot across multiple sessions, or comes with additional symptoms like bloody stool, fecal urgency, unexplained weight loss, or fever, that’s a different situation. These can point to gastrointestinal conditions that happen to flare with physical activity. Chronic, exercise-triggered abdominal pain with bowel changes is sometimes misattributed to a simple stitch for months before a proper evaluation, since the symptoms can look similar on the surface.