How to Prevent & Treat Runner’s Diarrhea (Trots)

Key takeaways:

• Runner’s diarrhea is common among long-distance runners and is often caused by a combination of movement, diet choices, and stress.
• Proper hydration and eating smaller meals before running that consist of easily digestible foods can help reduce symptoms in most runners.
• Learning to spot patterns and making small changes can often prevent runner’s diarrhea, but if it keeps occurring, a doctor can help with further options.

Runner’s diarrhea, also known as “the trots,” is a frequent and often frustrating issue for long-distance runners. It can cause loose or watery stools during or just after a run, which may affect comfort and performance. Although it’s usually not a serious health concern, understanding why it happens and knowing how to manage it can be a game-changer for many runners.

This article will explore what causes runner’s diarrhea, symptoms to watch for, and steps you can take to treat and prevent it. With the right approach, you can enjoy running with fewer digestive issues.

Definition of runner’s diarrhea

Runner’s diarrhea is when someone experiences loose or frequent stools either during or shortly after running. It’s most common in endurance runners, who put continuous movement and strain on their bodies for longer periods. This physical jostling can stimulate the digestive tract, making things move more quickly through the intestines, which often leads to loose stools.

Although it can be uncomfortable, runner’s diarrhea is generally manageable and doesn’t indicate a serious health issue. However, for runners preparing for events or races, it can be inconvenient and a few specific adjustments may improve comfort.

How long runner’s diarrhea typically lasts

The duration of runner’s diarrhea can vary depending on the individual and the specific cause. In most cases, symptoms last only for the duration of the run and resolve shortly afterward. For some, the effects may linger for an hour or two post-run.

However, if you experience prolonged diarrhea lasting more than a few hours or frequent episodes even when not running, it may be a sign of an underlying condition. Consult a doctor if symptoms are persistent.

Why runner’s diarrhea happens

Runner’s diarrhea happens when physical movement, diet, and stress all affect the digestive system. The jostling impact of running can stimulate the gut to work faster than normal, pushing food through the intestines before it’s fully digested.

The body redirects blood flow to the muscles to fuel activity, which temporarily limits blood available to the digestive system, sometimes leading to cramps or loose stools. Foods high in fiber, fat, or sweeteners, as well as anxiety before races, can all make symptoms worse.

Impact of intestinal jostling

The constant bouncing motion of running can shake up your digestive system, which might speed up how quickly food moves through your intestines.

This faster pace means food may not be fully digested, leading to loose stools. Runners who frequently experience this may find that choosing lower-fiber foods before running can help ease this effect.

Redistribution of blood flow

When you’re running hard, your body naturally sends more blood to the muscles to keep them working, which means there’s less blood available for your digestive system.

This shift can slow digestion and sometimes cause cramps or other digestive issues. Staying well-hydrated and eating foods that are easy to digest can help your body handle this redistribution more smoothly.

Dietary choices

Foods that are high in fiber, fat, or contain artificial sweeteners can be tough on your stomach before a run, often triggering digestive problems.

High-fiber foods are healthy but can cause gas and bloating, especially during intense exercise. Try eating lighter, easily digestible foods before running, like bananas or plain toast, to keep your stomach settled.

Stress and anxiety

Feeling nervous before a run or race can directly affect your digestion, as stress releases hormones that speed up your gut. This is why some runners experience an upset stomach or diarrhea when feeling anxious. Taking a few deep breaths and finding ways to stay calm before a run can help ease these symptoms.

Read our guides on different types of diarrhea and common causes of diarrhea for more.

Symptoms of runner’s diarrhea

Runner’s diarrhea comes with several noticeable symptoms that can help you identify and manage the condition more effectively.

Frequent bowel movements

Runners may feel the urge to have a bowel movement multiple times during a run, impacting their overall performance.

To reduce frequency, runners can practice gradual hydration leading up to a run and avoid eating large, heavy, or fiber-rich meals in the hours before a run or event.

Loose, watery stools

Diarrhea linked to running often results in watery stools, especially as the intestines fail to absorb enough water during quick transit.

Staying hydrated before and during exercise is key. Consider carrying water with electrolytes to replenish what’s lost through sweat, especially on longer runs.

Abdominal cramps

Cramps or a sense of discomfort in the lower abdomen can accompany diarrhea, often due to increased movement in the gut.

This sensation occurs when the intestines contract quickly, causing discomfort. Engaging in deep breathing exercises and maintaining a relaxed posture during your run may help reduce cramps. Opting for smaller, easily digestible meals before your run can also make a difference.

Urgency to use the bathroom

Many runners experience a sudden, strong need to find a restroom during their run. This urgency happens because the repetitive motion of running can cause the intestines to contract and speed up the movement of stool.

For some runners, this rapid movement is the body’s way of trying to clear the digestive system while focusing blood flow on the muscles, which might temporarily reduce blood supply to the intestines.

How to treat runner’s diarrhea at home

Managing runner’s diarrhea at home involves making minor adjustments to reduce digestive distress.

Stay hydrated

Staying hydrated is key to preventing dehydration, especially if diarrhea is an issue. Try to drink water steadily in the hours leading up to your run. Avoid drinking too much right before starting, as it can leave you feeling uncomfortable and cause a “sloshing” feeling in your stomach.

During your run, take small sips of water to keep up your hydration without overwhelming your stomach. For longer runs, electrolyte or sports drinks can be helpful because they not only replace water but also restore essential salts lost through sweat, which keeps your energy levels steady.

Opt for low-fiber meals

Choosing low-fiber meals before a run can help minimize digestive strain, reducing the chance of experiencing runner’s diarrhea.

High-fiber foods, while excellent for overall digestive health, can cause gas and bloating, leading to a faster gut transit time during intense physical activity. For this reason, it’s often beneficial to eat foods that are easier on the stomach, like bananas, white rice, or plain toast, before a run.

Avoid sugar and artificial sweeteners

Some people find that sugars and sweeteners like sorbitol or xylitol have a laxative effect, which can aggravate diarrhea. Choosing natural snacks without added sugars may help prevent symptoms.

Consider options like plain crackers or fruit as pre-run snacks. It may take a few tries, but it’s worth experimenting to find the foods that work best.

Read our guide on treating diarrhea at home for more.

How to prevent runner’s diarrhea

Prevention of further episodes of runner’s diarrhea often centers around dietary and lifestyle adjustments.

Establish a consistent routine

Eating and drinking at regular intervals can help your body adjust, making it less likely to experience digestive upset during a run.

Limit caffeine intake

Caffeine is a stimulant, thus it also stimulates the digestive system. This stimulant effect may increase the likelihood of diarrhea. If caffeine affects you this way, consider cutting back or choosing non-caffeinated options.

Experiment with timing and foods

Try different pre-run meals and timing to find what works best for your body. Once you find a routine that works, stick with it to maintain consistent digestion.

When to see a doctor about runner’s diarrhea

While runner’s diarrhea is common, some cases may require medical attention.

You should see a doctor if:

• Diarrhea persists beyond a few hours after running.
• Symptoms continue despite dietary adjustments and preventive steps.
• You experience mild abdominal discomfort or cramping that doesn't improve.
• You notice a small amount of blood in your stool.

You should go to the emergency room if:

• You experience black, tarry stools, which may indicate internal bleeding.
• There is a moderate amount of blood in your stool.
• Abdominal pain becomes severe or persistent.
• Severe dehydration symptoms occur, such as dizziness or confusion.

Questions to ask your doctor about runner’s diarrhea

If you’re experiencing ongoing issues, asking your doctor questions can help identify the best treatment plan.

• What foods should I avoid on days when I plan to run long distances?
• Are there any over-the-counter options that might help with my symptoms?
• Could any medications or supplements I’m taking be contributing to this issue?
• Do you recommend any tests to rule out other digestive conditions?

Frequently asked questions about runner’s diarrhea

Questions about managing runner’s diarrhea are common among athletes. Here are answers to some frequently asked concerns:

What should you do if you’re experiencing cramps and diarrhea after running?

If you experience cramps and diarrhea after a run, hydrate with small sips of water or an electrolyte drink to replace lost fluids.

A light snack, like a banana or plain toast, can help settle the stomach. If symptoms persist, rest and try a bland diet for the remainder of the day.

What if you’re experiencing explosive diarrhea after running?

Explosive diarrhea may signal that food or liquid passed through your system too quickly.

Hydrate gradually and consider lying down to ease the body. Avoid spicy or high-fat foods, which may irritate your digestive system further. If this continues after several runs, discuss options with a doctor

What can you do if you get diarrhea during a race?

If runner’s diarrhea strikes during a race, it’s best to stop running, locate a restroom as soon as possible, and take small sips of water to stay hydrated without upsetting your stomach further.

If symptoms persist or worsen, consider seeking medical attention to ensure safety. For future races, try sticking to the foods and routines that worked well during your training to help avoid similar interruptions.

Managing runner’s diarrhea

Runner’s diarrhea is a common challenge for many runners, especially during intense training or longer events. Although it can be uncomfortable, learning about the causes, symptoms, and ways to prevent it can make a big difference.

Staying hydrated and building a consistent pre-run routine are effective ways to reduce unpleasant symptoms and feel your best on race day. If runner’s diarrhea continues despite these steps, checking in with a doctor may offer extra insights and options to keep you running smoothly.

General Medicine follows a strict editorial process, including using real experts to write our articles, vetted primary sources, fact-checking, a secondary medical review, and updates as necessary. This article was medically reviewed and fact checked by Dr. Lane Thaut, DO.

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