Runner’s Diarrhea: How to Soothe Your System and Get Back to Running

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Runner’s diarrhea. As if you didn’t have enough to worry about while prepping for your next marathon. 

It can happen to anyone, and for distance and marathon runners, often does. 

Dr. Amy Oxentenko, a gastroenterologist and professor of medicine at the Mayo Clinic, defines this unfortunate experience as, “a change in stool form (looser or watery) or frequency (number of stools) that occurs in a runner, and may occur immediately before, during, or after running.” 

Runner’s diarrhea has a few names, including ‘runner’s trots’ and ‘runner’s colitis.’ 

Certain people are more prone to runner’s diarrhea, Dr. Oxentenko notes. People using diuretics, who have chronic irritable bowel syndrome, or whose digestive tract has been damaged are more likely to suffer from this. It also tends to affect younger runners more than older runners, and more women than men. 

If this has happened to you, don’t fret.

runner's diarrhea after running

Runner’s diarrhea is incredibly common, most often seen in runners of three miles at a time or more. This means most people training for a marathon are bound to experience it at one point or another. 

A survey of 707 runners in a marathon revealed a whopping 19% of participants had diarrhea at some point during the race. In addition, 10% of those surveyed had to head for a restroom break in the middle of their run! 

Fortunately, there are many steps you can take to prevent this from happening to you.

But first, let’s take a look at the causes. 

The Top Causes of Runner’s Diarrhea

runner's diarrhea

Frustratingly, when this condition happens, the cause isn’t always clear. A lot is going on inside your body during distance running, and any one of them could trigger a rebellion. 

The constant up and down motion of running puts more physical strain on the body than usual. Your digestive system will still need to perform all its normal functions under greater stress, and it does not always like this.

Running reduces blood flow in the intestines. When exercising, that blood flow slows down and redirects to other places that need it, such as your torso and leg muscles. 

Food intake can be a factor. An electrolyte imbalance could be putting things off-kilter. Other possible culprits include foods high in fiber, spicy foods, caffeine, or dishes containing lots of fat. 

Changes in hormones may set it off. Exercise that requires high endurance such as running cues the body to release the stress hormone, cortisol. Cortisol can then make you feel like you need to go to the bathroom. 

Too much stress and anxiety in general is never a good thing. But in this case, they can actually irritate your system and trigger diarrhea. Yet another reason to breathe deeply and find your center. 

Related article: Running With A Cold

Runner’s Diarrhea Prevention Tip #1: Eat Like a Runner

runner's diarrhea

The best way to make sure your digestive system behaves on race day is to give it less to do. For this, we have three methods.

Try to avoid eating for at least two hours beforehand.

This spares your system from having to work hard while you’re running. Plus, keeping your digestive tract empty will minimize the need for any bowel movements.

Eat the right types of meals.

Foods that bind well are good options for what to eat before running. Keep them super simple so that less waste is left over when they digest. This will mean less bowel movements for you. 

The BRAT diet has some great examples. BRAT stands for:





This diet is usually for calming symptoms once they’re already happening. But for a runner, it can help stop them from cropping up in the first place. Try to stick whole grain rice (not white) for even better results. 

Know what to avoid

It’s just as important to know which foods to skip to avoid triggering the condition. Stay away from anything with:

  • High fiber content such as beans or lentils
  • Large amounts of fat
  • Spiciness
  • Sugar alcohols taking the place of real sugar
  • Dairy if you’re lactose intolerant

If you’re considering trying anything new, include it in your diet during training, not on race day. You don’t want to end up with surprise stomach issues. 

Choosing the right foods with all of their complex ingredients can be tricky. Make it easy on yourself by using a marathon training meal plan that takes the guesswork out of what to eat. Meal plans aren’t just for building muscle and weight loss. 

Prevention Tip #2: Wear Comfortable Clothing

runner's diarrhea

Clothing that is too tight around your midsection can restrict blood flow. This can not only irritate your digestive tract, it could make you much more uncomfortable if you start to feel symptoms. The very last thing you will want if you need to go to the bathroom is more pressure from clothes. 

Keep them light and flowy, or at the very least, with plenty of stretch. With the right layering, this can work even while running in cold weather.

Prevention Tip #3: Visit the Bathroom Just Before Running

runner's diarrhea portapotty

If you can, empty your bowels right before your race or distance run. A mild laxative the night before may help make that possible.

If you’re planning on going just before the race starts, arrive early so you don’t get stuck behind any long lines. 

Chances are other runners will be doing the same thing. 

Runner’s Diarrhea Prevention Tip #4: Drink Plenty of Water

Runner’s Diarrhea: How to Soothe Your System and Get Back to Running 1

Hydration is key with any form of exercise, and running is no different. For diarrhea in particular, dehydration can be a trigger (dehydration and distance running can lead to running with hemorrhoids.). 

As mentioned in the food section, sugary drinks with fructose can send you racing for the bathroom. Opt for plain water or healthy alternatives like coconut water or natural fruit juices instead. 

Skip the coffee. Caffeine can increase intestinal contractions and worsen cramping. It also functions as a mild diuretic. 

Remember, warm liquids can speed up the digestive tract, so keep them cold!

Runner’s Diarrhea Prevention Tip #5: Pain Relievers Come After the Run

runner's diarrhea stomach problems

While it may sound proactive to stock up on pain-blocking meds before your big run, they’re not a good idea.

Anti-inflammatory medications like ibuprofen or naproxen can actually irritate your stomach.

Save them for later.

Emergency Rescue Tricks to Save You on Race Day

If you feel the sudden, very urgent need to find the nearest restroom, don’t panic.

You don’t necessarily have to pack up and go home. Keep the following tips in mind.

With a little luck (and accessible portable toilets), you’ll be able to keep calm and carry on.

runner's diarrhea

Plan your route beforehand. 

Knowing where you’ll be running could be a lifesaver. For a marathon or just a run through your neighborhood, have a general idea of where you’ll be going. Take note of places you could stop along the way if disaster strikes.

Stop for a moment. 

Sure, now feels like a great time to sprint home. But take a second to walk slowly or even come to a complete stop. The change may win you a bit of control over the urgency. 

Also, the fight to keep everything where it should be is probably affecting your posture. You don’t want to risk injury by continuing on like that. Come to a halt and use that time to scan the area for the closest place to do what you need to do. 

Sip water throughout whenever possible. 

Each time you sweat or dip into a public restroom en route, you’re losing fluids. When you can, replenish those. Bonus points if you pick a drink that includes electrolytes

Try not to worry about it too much if it does happen.

Like we mentioned earlier, it happens to the best of us. Sometimes we are at the mercy of our own bodies. Take these two marathon runners, Catherina Mckiernan in 1998 and Paula Radcliffe in 2005 as consolation.

Both runners came down with marathon diarrhea at the very worst time, but they still went on to win the whole race. 

When to Get a Doctor Involved

In most cases, runner’s diarrhea is temporary and will go away in a couple of days. If it happens to you a lot, though, you’ll want to see a professional to figure out the cause. 

Important issues to watch out for:

  • You get diarrhea often even when not running
  • It happens suddenly with no change in lifestyle and no obvious cause
  • There’s blood in your stool
  • You have abdominal pain or fever

In these cases, you could have a serious underlying problem on your hands. These symptoms could indicate a wide range of issues, from inflammatory bowel disease to infection. Take them seriously, and don’t wait. 

runner's diarrhea

Any number of things can happen to your body during distance running. Make sure you’re prepared beforehand, stay alert for any warning signs, and know what to do if diarrhea does start at a bad time. 

Pushing yourself too hard or for too long can be harmful to your body, so having a good marathon training plan is essential. Download your free plan here – You’ll find one to fit your individual fitness level, no matter where you’re at in your running journey.

Photo of author
Mia Kercher is a hiker, cyclist, and runner. After finishing her first marathon in 2013, she continued the sport but found a new passion in trail running. She now explores the glorious mountains in Portland, Oregon.

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