5 min Read

Runner’s trots, runner’s colitis, runner’s diarrhea — Although known by many names, this condition is characterized by the same symptoms: frequent and loose bowel movements immediately after or during a run.1

While it is a condition that can easily be treated with OTC diarrhea medicine, runner’s diarrhea can be more than a mere inconvenience. Learn the typical reasons why it happens and the most effective ways you can prevent it below.


Runner’s Diarrhea: Why Does It Happen?

Anyone can experience diarrhea. But despite its name, not all runners have the same susceptibility to runner’s diarrhea.

Long-distance runners – particularly those who run three miles or more within a given time – have a higher risk of experiencing the trots.1 One study revealed that 62 percent of long-distance runners reported having to stop mid-marathon for a bowel movement.2

Besides making frequent trips to the bathroom, other symptoms of runner’s diarrhea include:

✓  Stomach cramping3

✓  Flatulence3

✓  Bloody stools4

✓  Nausea4

✓  Vomiting4

But why does it happen?

Though the direct cause isn’t clear, studies revealed that runner’s diarrhea could be affected by mechanical, gastro-intestinal, and nutritional factors.5


Running is not only hard on your joints but also on your intestines. The harder you run, the more the internal organs in your abdomen are jostled around like kids inside a bounce house.4 This is also why long-distance runners experience gas and the sudden urge to use the bathroom (sometimes even bloody stools).4


Diarrhea and other gastrointestinal (GI) symptoms are affected by the intensity of exercise. In short, the harder you run, the more severe your diarrhea can be.4

This could be the reason why runners experience diarrhea during races and intense workouts.

A common factor blamed for this is the reduced blood flow to the intestines6. The "delivery" is reduced by as much as 80 percent6, causing a shortage of oxygen and energy. Without sufficient supply, the tissues in the intestines become more vulnerable to toxins that cause diarrhea (a.k.a. leaky gut)4 6.


The contents of your stomach also affect your risk of runner’s diarrhea4. Some studies discovered that high-carb beverages might cause fluid shifts in the intestine, resulting in runner’s diarrhea4.

Foods that delay gastric emptying are potential GI symptom inducers4, such as:

✓  Fats4

✓  Fiber4

✓  Protein4

Besides staying longer in the gut and causing discomfort, these three also draw water and result in loose bowel movement.4

Runner’s Diarrhea Prevention: 3 Simple Ways

With anti-diarrhea medicine for adults available over the counter, treatment of diarrhea is pretty straightforward.

But if you’re a long-distance runner and have frequent bouts with runner’s diarrhea, these three ways to prevent it could be very helpful:

1. Check your lifestyle

Effective treatment of runner’s diarrhea begins with your lifestyle and diet.4
What you wear during a run also affects your risk level. Anything too tight worn around the midsection constricts the blood flow7, causing discomfort and GI symptoms like diarrhea in the same manner as a condition known as “tight pants syndrome”7.

2. Watch what you eat before a run.1

Avoid eating anything two hours before you run.1

A day before running, eat less to zero gas-inducing, high-fiber foods like fruits, salads, bran, and beans1. If you’re a daily runner, figure out your fiber tolerance. If this doesn’t work, just stick to eating these foods after you run.1

Avoid consuming anything with sweeteners known as “sugar alcohols.” This includes isomalt and sorbitol, commonly found in sugar-free gum, candies, and ice cream.1

3. Drink enough

Proper hydration is crucial when working out, and running is no exception. Drinking enough can also prevent runner’s diarrhea.
Dehydration or overhydration both cause digestive distress.1
Take note: Don’t drink any warm liquids as they can hasten the passing of food during digestion.1

Run Without Any Worries

Managing runner’s diarrhea – or better yet, preventing it – is possible. With the right knowledge and help from reliable over-the-counter diarrhea medicine, you can run marathons without any worries.

Browse Our Products

Enterogermina®’s range will scan the gut for intestinal flora imbalance and deliver billions of good bacteria to treat both the condition and associated symptoms. 14