How to deal with side stitches while running: causes & fix

Photo by Caique Araujo on Pexels

You’re 12 minutes into a run, finally settling into a rhythm, when it hits — a sharp, grabbing pain under your right ribs that makes you want to fold in half. Maybe you slow down. Maybe you stop completely and press your fist into your side like that’ll help. It’s called a side stitch, and if you’ve had one, you know it can turn a decent run into a miserable shuffle home.

The medical name is “exercise-related transient abdominal pain” (ETAP), which tells you nothing useful, so let’s skip the jargon. What matters is this: side stitches are common, they’re not dangerous, and there are specific things you can do both mid-run and in your training to stop them hijacking your runs. This isn’t one of those injuries that needs rest and patience — it’s mostly fixable with timing, breathing, and a few adjustments most runners never think to try.

If you’re newer to running, side stitches can feel like proof something’s wrong with you. It isn’t. Up to a third of runners get them regularly, and plenty of experienced marathoners still deal with them occasionally. This is a fixable, known problem — not a sign you’re not cut out for this.

What’s actually causing the pain

The most widely accepted explanation is that a side stitch is a cramp or irritation of the diaphragm — the muscle that separates your chest from your abdomen and does the heavy lifting of breathing. When you run, especially at a harder effort, your diaphragm works overtime. Combine that with a full stomach, shallow breathing, or poor posture, and you get localised strain or even irritation of the ligaments connecting your diaphragm to your internal organs.

A few things reliably increase your risk:

• Eating too close to your run — especially large meals, high-fat foods, or sugary drinks within 1–2 hours of running
• Shallow, chest-based breathing — common when you’re running faster than your fitness comfortably allows
• Dehydration — oddly, both too little and too much fluid in your stomach can be a factor
• Poor core strength or posture — a collapsed running posture puts more strain on the diaphragm
• Starting too fast — stitches are far more common in the first 20 minutes of a run than later

Notice that none of these are about toughness or genetics. They’re mechanical and dietary — which means they’re adjustable.

The fastest way to fix it mid-run

When a stitch hits, your instinct is probably to stop or grimace through it. Neither works that well. Try this instead, in order:

1. Slow down, don’t stop. Dropping to an easy jog or brisk walk keeps blood flowing without fully resetting your breathing pattern.
2. Exhale hard on the opposite side to the pain. If the stitch is on your right, breathe out forcefully as your left foot strikes the ground. This changes the pressure rhythm on your diaphragm and is one of the few in-run fixes with decent evidence behind it.
3. Press into the spot and bend forward slightly. A firm press with your fingers, combined with a slight forward lean, can ease the cramp within 30–60 seconds.
4. Breathe deeply into your belly, not your chest. Three to five slow belly breaths — in through the nose, out through the mouth — often resets things faster than panicked shallow breathing.

Most stitches ease within 1–3 minutes if you address them this way. If the pain is severe, spreads to your shoulder, or comes with chest tightness or shortness of breath unrelated to effort, stop running and treat it as a medical concern rather than a stitch — that’s a different situation entirely.

Fixing the cause, not just the symptom

If you’re consistently getting stitches on easy runs, the most common culprit by far is starting too fast. Even experienced runners do this — the first kilometre feels “easy enough” at a pace that’s actually 30–45 seconds/km quicker than it should be. Slowing your first 10 minutes down deliberately fixes more stitch problems than any breathing trick.

Breathing patterns that actually help

Most runners breathe without thinking about it, which is fine until it isn’t. A simple rhythm worth practising on easy runs: inhale for 3 footstrikes, exhale for 2. This odd-numbered pattern means you’re not always exhaling on the same foot, which some research suggests reduces the repetitive strain on one side of the diaphragm — a plausible mechanism, even if it’s not proven to eliminate stitches outright.

Practising this on easy runs matters more than trying to remember it mid-stitch. By the time the pain hits, you’re already stressed and your breathing is already erratic — that’s the wrong moment to learn a new skill. Build the habit on your recovery days when nothing’s on the line.

Core strength: the unglamorous long-term fix

A weak or unstable core doesn’t cause stitches directly, but it makes your running posture collapse more under fatigue, which increases diaphragm strain. You don’t need a six-pack. You need basic anti-rotation and anti-extension strength — the ability to keep your trunk stable while your arms and legs move.

A simple twice-weekly routine:

• Plank, 3 x 30–45 seconds
• Dead bug, 3 x 10 per side
• Bird dog, 3 x 10 per side
• Side plank, 3 x 20–30 seconds per side

Ten minutes, done consistently, tends to show up in fewer stitches within about a month — not because your abs look different, but because your trunk holds its shape better at minute 35 of a long run when you’re tired and your form starts to slip. If you want a fuller pre-run routine too, a solid warm-up routine primes your breathing and posture before you even start running, which matters more than people assume.

What to eat and drink before running (and when)

This is where a lot of avoidable stitches come from. The timing matters as much as the food itself:

• 3+ hours before: normal meal, anything goes
• 1–2 hours before: moderate carbs, low fat, low fibre — think porridge, toast with honey, a banana
• 30–60 minutes before: small and simple only — half a banana, a few dates, an energy gel if it’s a longer run
• During the run: sip, don’t gulp. Large volumes of fluid or sugary gels taken too fast are a classic stitch trigger, especially on humid days when you’re drinking more than usual.

If you’re training for longer distances and experimenting with race-day fuelling, get your gut used to it in training first — stitches and GI issues both spike when people try new fuelling strategies on race day itself. The NHS has useful general guidance on staying properly hydrated for exercise if you want a baseline to work from.

When stitches mean something else

Occasionally what feels like a stitch is something else worth paying attention to — a strained intercostal muscle, referred pain from tight hip flexors, or in rare cases, something unrelated to running at all. If the pain:

• Lasts more than 10–15 minutes despite slowing and breathing changes
• Keeps recurring at the exact same spot every single run
• Is accompanied by nausea, dizziness, or unusual fatigue

…it’s worth mentioning to a GP, particularly if you’re newer to running or returning after a long break. This is the exception, not the rule — most stitches are just stitches. But persistent, localised pain deserves a second look rather than being pushed through indefinitely.

The Honest Takeaway

• Tomorrow’s run: start slower than feels necessary for the first 10 minutes — this alone prevents more stitches than any technique.
• If a stitch hits mid-run, slow down (don’t stop), exhale hard on the side opposite the pain, and take 3–5 deep belly breaths.
• Eat your pre-run snack 60–90 minutes out, and keep it small and low-fat — porridge and banana beat a fry-up every time.
• Add 10 minutes of core work twice a week. It won’t show up this week, but by week four you’ll notice your posture — and your stitches — holding up better late in a run.
• If the pain is severe, one-sided every single time, or comes with other symptoms, treat it as worth checking rather than something to just run through.

Next read: Dealing with a bad run: how to bounce back