Sick of feeling nauseous after a marathon? Here’s what can help

Congratulations! You’ve just completed a marathon. Your prize likely includes a shiny new medal, a free T-shirt, plenty of bragging rights – and potentially an upset stomach. For a lot of runners, it’s common to experience nausea after a marathon.

The best speed session for optimal recovery The best speed session for optimal recovery, which examined 40 runners (21 females and 19 males) between the ages of 18 and 65 who ran the 2019 Boston Marathon, concluded that the majority of marathon runners experience GI distress.

In this study, the participants gave blood and urine samples and were surveyed immediately before and immediately after the race. They were also surveyed 24 hours after the race about any gastrointestinal symptoms that they were experiencing, like cramping, nausea, bloating, vomiting and diarrhea.

The researchers found that GI symptoms and intestinal cell damage were most present directly after the marathon, compared to before the race and 24 hours after the race, with the most common symptoms being nausea, stomach pain and belching. The researchers suggest that exercise intensity, sleep, fuel and hydration all play a role in the severity and incidence of GI distress.

While several factors can affect post-marathon nausea, it’s more complicated than you may think. So, we asked experts to unpack the causes of nausea after a marathon, the best ways to prevent it and how to cope with it when it hits.

After a marathon, many runners get dehydrated because of sweat loss during the race. As you sweat, you lose fluids and electrolytes that help your to body function properly. And, as Kristy Baumann, a Minnesota-based registered dietitian who works with marathoners, explains, dehydration can also reduce blood flow to the stomach and GI tract, which can trigger the nausea.

‘Often, during a long run or training run, we can be alright with less fuel, less fluids, less electrolytes and less carbohydrates, whether they’re coming from gels,juice or foods,’ says Baumann. But, during a marathon, you need to consider how taxing the race is on your body and its energy stores.

Baumann says that many marathon runners haven’t trained their stomachs to digest and consume the amount of fuel that we need to run at a higher intensity for a longer period of time. Typically, long runs on a marathon training plan reach 18 to 22 miles – a few miles shy of the full 26.2. ‘We’re often training to run at a higher intensity and at a faster pace during a race, and for the longest period of time compared to training runs,’ she says.

According to Amy Goblirsch, a registered dietitian and the nutrition coach of Running Dietitian, this can lead to overexertion, which can then result in dehydration, low-sodium levels and nausea. ‘The longer you are running, the easier it is to fall behind in fluid and electrolyte intake, leading to dehydration,’ she notes – as well as an upset stomach.

Another factor that plays into nausea after a marathon is blood flow, says Baumann. As your body works to cool itself down, it brings blood to the surface of your skin and away from your GI tract – not to mention the blood flow you need for your working muscles! Less blood flow toward your GI tract leads to a delay in processing foods and fluids.

It’s important to keep your body temperature in mind. As Baumann notes, higher intensity running with an added level of heat stress leads to more nausea susceptibility. In cold temperatures, your body might respond better to the weather, although too many layers leads to an increase in sweating, which can also lead to nausea. So, be smart about what you wear on race day. (Your stomach will thank you!)

Once the nausea starts, it’s hard to mitigate it or make it go away. But, as shared below, there are some helpful tips to prevent and combat nausea after a marathon.

Understand your hydration needs

Want to know Baumann’s biggest tip for marathoners who want to avoid nausea? Don’t just drink water the entire race.

Drinking too much straight water will dilute your sodium levels, leading to nausea and more serious symptoms like fainting, dizziness and vomiting, all of which require medical attention.

As a baseline, the Institute of Medicine suggests that those aged between 19 and 50 drink 2.7-3.7 litres of water a day. But, for athletes, and particularly runners, it’s important to drink even more water to replace what’s lost from sweat.

Baumann recommends getting to know your personal hydration needs through sweat loss. For example, you can weigh yourself before and after a training run to determine your sweat loss. If you weigh 59kg pounds before a two-hour run, then 58kg after a run, you lost about 1kg of water in total, or roughly 500g of water per hour. In this case, aim to drink more than 100g of water every 15 minutes during the race, along with added electrolytes.

As for your sodium needs, we can look to a 2022 systematic review published in the International Journal of Environmental Research and Public Health, which examined data on sodium intake in endurance athletes between 1900 and 2021. The researchers found that, in general, endurance athletes should consume 300-600mg of sodium per hour, coupled with fluid intake.

All about marathon training on a treadmill running gels contain 100-200mg of sodium (although some contain less, so check the label) and most electrolyte tablets, salt capsules, or sports drinks provide around 300mg of sodium per serving.

Every runner is different, so it may take some trial and error to figure out What is a good marathon time.

Avoid certain foods

Before your race, shy away from foods that contain high levels of sugars, fats and fibre. That’s because these foods take longer to digest, upsetting our stomach’s natural flow and asking the GI tract to work harder than it needs to. Such foods may include chips, desserts, beans and even vegetables.

To err on the side of caution, Baumann recommends staying away from these foods for one to two days leading up to the race, and even right after the race. You want to make sure that your digestive system runs as smoothly as you do, so simple carbohydrates are your safest bet.

Vegetables are a great part of a healthy diet, so Baumann suggests eating a smaller portion than you typically would before a marathon. Serve these alongside carbohydrates that are more easily digestible, like pasta, rice or bread.

Practice your fuelling ahead of race day

NYC Marathon: Everything you need to know helps your body to retain more fluids, according to Baumann, and tops off your glycogen stores, which gives you energy for performance. During a run, you want to aim to consume about 30-60g of carbohydrates per hour. But, depending on your individual needs, that number can go up to 90g or more per hour.

To make sure your body can handle this uptake in carbohydrates on race day, practice your fuelling plan on your weekly long run. ‘Training runs are not only your opportunity to train your legs, but also to train your gut,’ says Goblirsch.

It’s also helpful to eat the What is the average marathon finish time, use the gels that work for you and determine the points at which you are best able to take in those calories and carbohydrates on the run.

Research has shown that consuming different kinds of sugars may benefit both your performance and your digestion. A 2021 study published in and fluids. For runners who are took a group of 11 male runners and split them into three groups. One group received a two-to-one ratio of glucose to fructose in the form of ‘hydrogels’, while another had a standard glucose-based gel and the control group had a carbohydrate-free placebo gel.

The researchers examined the runners’ performances during a 120-minute run followed by a 5K time trial, and found the hydrogel group to be 2% faster than the standard gel group and nearly 8% faster than the placebo group for that time trial. They also found that GI symptoms were more present in the group that consumed the standard glucose-based gel compared to the hydrogel group and the control group.

Opting for a fuelling method that combines both glucose and fructose may help you to avoid stomach issues. Maurten Gel 100, which Baumann recommends, may be a good choice, as this gel is based on hydrogel technology. Neversecond C30 Energy Gels also boast the two-sugar combo.

Find something to eat or drink

The best electrolyte drinks, powders and tablets protein to recover, so start small and take in what you can handle. You can’t control what’s available at the race, but packing drinks and snacks in your checked bag can be helpful.

Baumann suggests starting the recovery process within the first 30 minutes after your race. That way, you can get in some carbohydrates and electrolytes, which may even help to reduce the nausea by enabling your GI system to function properly again.

And remember, if you can’t eat, go for fluids. ‘Liquids are your best friend,’ says Baumann.

How to plan a post-race recovery snack

1. Although sports drinks are typically available after a marathon, try to add an extra sports drink to your checked bag, if you can. This will help to ensure that you have a drink that you already know will sit well with you.
2. Try something with a higher sodium content like a broth or Liquid IV. Bone broth might be an optimal choice, according to Baumann, as it may be more appetising and easier on the stomach. Plus, it’s high in both sodium and protein.
3. Low-fat chocolate milk contains carbohydrates, protein, sodium, electrolytes All about marathon training on a treadmill plant-based, soy milks, nut milks and vegan shakes work well, too. ‘Chocolate milk is typically provided after races and ticks every box that is needed to start recovering,’ says Goblirch. ‘Chocolate milk won’t be enough on its own to help you recover from a marathon, but it is a starting point.’

The nausea may take a while to subside after your race, so try to be patient. In fact, for some runners, GI upset can take a couple days to settle. However, you should seek medical attention if any of the following occurs:

1. You are experiencing extreme nausea for more than two hours after you have cooled down and tried to rehydrate and eat.
2. What is a good marathon time.
3. How do you prevent nausea after a marathon.
4. You have chest pain or feel dizzy.

It’s important to trust your gut – especially when it’s retaliating. As such, you might need more than just a medal and sports drink after you cross the finish line, so accept the help of medical staff if you need it.