Runner’s Stomach: What It Is, What Causes It, and How to Get Relief

You lace up your running shoes, head out the door, and start your run feeling great. But somewhere along the way, your stomach starts cramping, gurgling, or worse—you feel an urgent need to find a bathroom. If you’ve experienced this, you’re not alone. It’s something runners all over the world deal with, and it even has a name: runner’s stomach.

Runner’s stomach isn’t just uncomfortable; it can totally derail a training session or race day. And for new runners or those prepping for a big event, it can be frustrating and embarrassing. The good news? You can learn to manage it. In this guide, we’ll talk about what causes runner’s stomach, why it happens, and how you can get it under control.

This article is for anyone who runs, whether you’re training for a 5K or a marathon. And if you're just getting into running and wondering why your stomach sometimes rebels, you're in the right place too.

What Is Runner’s Stomach?

Runner’s stomach is a term used to describe gastrointestinal (GI) issues that happen during or after running. It includes things like cramping, nausea, bloating, gas, and diarrhea. Some runners feel a need to go to the bathroom right away, while others experience discomfort for hours after their run.

While the symptoms can range from mild to severe, they’re usually not dangerous. However, they can be extremely disruptive and make running feel like a punishment instead of a joy.

GI issues during exercise are common, especially in endurance sports like running. Studies suggest that 30 to 50 percent of long-distance runners experience some type of gastrointestinal discomfort. But just because it's common doesn't mean you have to live with it.

What Causes Runner’s Stomach?

To understand why your stomach acts up during a run, it helps to look at how your body works when you're exercising. Several things happen in your body when you start running, and some of those changes can affect your digestive system.

1. Reduced Blood Flow to Your Digestive System

When you run, your body diverts blood away from your digestive organs and sends it to your muscles and heart. This makes sense—your body wants to fuel your movement. But the downside is that your stomach and intestines get less blood, which can slow digestion and irritate your gut.

This condition is sometimes referred to as exercise-induced gastrointestinal syndrome. It can cause cramping, nausea, and even diarrhea, especially during longer runs.

2. The Jostling Effect

Running, especially on hard pavement, causes your body to bounce up and down repeatedly. All that jostling can disturb your stomach and intestines. If you have food or liquid in your gut that hasn't been digested yet, the bouncing can make everything feel worse. This can lead to that sloshy, crampy feeling mid-run.

3. Dehydration and Electrolyte Imbalance

Even slight dehydration can upset your stomach. When you're dehydrated, your digestive system doesn’t function properly. And when you sweat, you also lose electrolytes like sodium, potassium, and magnesium, which help regulate muscle contractions, including those in your intestines. This imbalance can contribute to nausea, cramping, or diarrhea.

4. Eating the Wrong Foods Before a Run

What you eat before running plays a big role in how your stomach feels. Foods that are high in fiber, fat, or dairy can be hard to digest, especially if you eat them too close to your run. This can lead to gas, bloating, and discomfort. Even healthy foods can cause problems if they’re not timed right.

5. Stress and Anxiety

Feeling nervous before a big run or race? That stress can trigger gastrointestinal symptoms too. There’s a strong connection between the brain and the gut, often referred to as the gut-brain axis. When you're anxious or stressed, your body releases hormones like cortisol, which can speed up or slow down digestion, leading to cramping, nausea, or urgent bathroom trips.

6. Caffeine and Energy Gels

Caffeine is a common pre-run stimulant, but it can also stimulate your bowels. While that might be helpful for some people, it can lead to emergency bathroom situations for others. Similarly, energy gels and sports drinks can contain sugar alcohols or ingredients that irritate the gut, especially when taken in large amounts or without water.

Who’s Most at Risk for Runner’s Stomach?

Runner’s stomach can affect anyone, but certain groups are more likely to experience it:

• Long-distance runners: The longer you're out there, the more stress you put on your gut.
• New runners: If your body isn’t used to the movement and jostling, it may be more reactive.
• Women: Hormonal fluctuations throughout the menstrual cycle can influence digestion.
• People with sensitive stomachs: If you have a history of IBS, IBD, or food intolerances, you're more likely to struggle with GI symptoms during exercise.

Knowing your risk factors can help you make smarter decisions about your training, diet, and hydration.

How to Prevent Runner’s Stomach: Practical Tips That Work

There’s no one-size-fits-all solution, but there are several strategies that can significantly reduce your chances of getting runner’s stomach. It might take a little trial and error to find what works best for you, but these tips are a good place to start.

First, pay attention to what you eat before a run. Avoid foods that are high in fat, fiber, or dairy, especially within two to three hours of running. Opt for something easy to digest like a banana, toast with a bit of peanut butter, or oatmeal.

Make sure you’re hydrated, but not overly so. Drinking too much water right before a run can make your stomach slosh and lead to cramps. Aim to stay consistently hydrated throughout the day instead of chugging water just before you head out.

Electrolytes matter too. If you’re going on a long run (over an hour), consider taking an electrolyte drink or tablet to replace what you lose in sweat. But be cautious with sugary sports drinks or energy gels, especially if you haven’t tested them during training.

Try to time your meals so you’re not running on a full stomach. Most people do best when they eat their last meal two to four hours before a run. If you need a small snack closer to run time, keep it light.

Stress management can also help. If you get nervous before races, practice calming techniques like deep breathing, meditation, or visualization. Managing pre-run nerves can help calm your stomach too.

And perhaps most importantly: train your gut. Just like you train your muscles, you can train your digestive system to handle food, fluids, and gels during running. Try different nutrition strategies during training runs so your body gets used to them before race day.

What to Do If You Get Runner’s Stomach During a Run

Even with all the preparation in the world, runner’s stomach can still strike. If it happens, don’t panic. First, slow down. Reducing your pace can help calm your body and reduce the intensity of symptoms.

If possible, find a bathroom or a private place to relieve yourself. If you're feeling nauseous, take small sips of water and walk for a bit. Sometimes adjusting your breathing can help too—try to take slow, deep breaths to relax your body.

And if the symptoms are really bad? It’s okay to call it a day. One run isn’t worth risking your health or comfort. Learn from the experience and think about what might have triggered it so you can adjust for next time.

Long-Term Solutions: Building Gut Resilience

If you deal with runner’s stomach regularly, it’s worth looking at your overall gut health. Eating a balanced diet rich in whole foods, fermented foods (like yogurt, kimchi, and kefir), and prebiotic fiber can support a healthy gut microbiome.

Some runners benefit from taking probiotics, although results vary from person to person. If you’re considering supplements, talk to a healthcare provider or a registered dietitian.

Keeping a food and run journal can also help. Write down what you ate, when you ate it, how your run felt, and any symptoms you experienced. Over time, you may spot patterns that can help you fine-tune your nutrition and training.

When to See a Doctor

While most cases of runner’s stomach are harmless, there are some red flags to watch out for. If you notice blood in your stool, have persistent GI issues even when you're not running, or experience severe pain, it’s time to see a doctor. These could be signs of something more serious, like inflammatory bowel disease or a food allergy.

Don’t ignore chronic symptoms just because they seem common. Getting checked out can help you feel better and improve your performance.

Final Thoughts

Runner’s stomach might be common, but it doesn’t have to be part of your regular running experience. By understanding what causes it and taking steps to prevent it, you can make running more enjoyable and less stressful.

Every runner is different, so what works for one person might not work for another. Be patient with your body, experiment with your nutrition and hydration, and don’t be afraid to take rest days when needed. The more in tune you are with your body, the better your runs will feel—and the fewer bathroom sprints you’ll have to make.

Ready to run strong and stomach-symptom free? Start with these tips and listen to your body. You’ve got this.

For more science-backed health and wellness advice, check out other articles on meto.co.

Frequently Asked Questions About Runner’s Stomach

1. Is runner’s stomach dangerous?

In most cases, a runner’s stomach is not dangerous—it’s just really uncomfortable. The cramps, nausea, or sudden need to find a bathroom usually go away shortly after your run. However, if you experience persistent or severe symptoms (like vomiting, blood in your stool, or ongoing GI issues), it’s important to speak with a doctor. It might be something more serious like IBS, colitis, or a food intolerance.

2. Can beginners get runner’s stomach too?

Yes, absolutely. In fact, new runners might be more likely to experience runner’s stomach because their bodies haven’t fully adjusted to the physical stress of running. Beginners may also be unaware of how certain foods, hydration habits, or nervous energy before a run can impact digestion.

3. Should I eat before running to avoid runner’s stomach?

It depends. Some people do better with a small snack before running, like a banana or a slice of toast, while others prefer to run on an empty stomach. The key is to avoid high-fiber, high-fat, and dairy-heavy foods right before your workout. It may take some trial and error to see what works best for your body.

4. Does the time of day you run affect your stomach?

Yes, it can. Some runners notice they have fewer stomach issues when they run in the afternoon or evening, after their digestion has had time to “wake up.” Others find that morning runs on an empty stomach feel better. Again, everyone is different—experimenting with run timing might help you find what’s easiest on your gut.

5. Can you take something to prevent runner’s stomach?

Some runners take anti-diarrheal medications like Imodium before races, especially if they’re prone to digestive issues. But this isn’t something you should rely on regularly. A better long-term approach is adjusting your diet, hydration, and training routine. If needed, a sports dietitian or GI doctor can help guide you.

6. Does stress or anxiety cause runner’s stomach?

Yes, mental stress can play a big role. The gut is closely connected to your brain through something called the “gut-brain axis.” If you’re feeling nervous about a race or putting pressure on yourself to hit a certain pace, your digestive system might react. Practicing relaxation techniques, like breathing exercises or mindfulness, can actually help.

7. How long does runner’s stomach last?

Most of the time, symptoms go away within a few hours after running. Drinking water, eating a bland snack (like crackers or toast), and resting usually help. If symptoms last more than a day or keep coming back, it’s worth checking in with a healthcare provider.

8. Can dehydration cause runner’s stomach?

Yes! When you’re dehydrated, your digestive system doesn’t function as smoothly. This can lead to cramping, nausea, or diarrhea. It’s important to drink enough water before, during, and after your run—but don’t overdo it either. Too much water, too quickly, can also upset your stomach.

9. Is it okay to keep running if I feel stomach cramps during a run?

It depends on how bad the cramps are. If it’s just mild discomfort, you might be able to slow down or take a walking break and still finish your run. But if the cramps are intense or paired with nausea or dizziness, it’s best to stop, rest, and hydrate. Listening to your body is always the safest move.

10. Can women experience runner’s stomach more often around their period?

Yes, hormonal changes before and during menstruation can affect digestion. Some women notice they’re more prone to cramping, bloating, or GI urgency around their period. Tracking your cycle can help you prepare and adjust your running schedule or diet accordingly.