Coming Back from a Stomach Bug: Gastroenteritis Treatment for Athletes

By Jim Rutberg, CTS Pro Coach & Co-author “The Time-Crunched Cyclist”

A stomach bug is one of the most dreaded circumstances for an athlete preparing for a goal event. Whether it is from a bad plate of food (bacteria) or something your kids brought home from school (virus), you have most likely have minor gastroenteritis and the end result will be a physically draining but relatively short-lived experience that encompasses vomiting, diarrhea, or sometimes both.

As coaches, we get plenty of panicky calls from athletes who come down with gastroenteritis in the week leading up to a goal event. This is often the time when athletes get sick because they are either traveling to an event and eating/drinking in areas they’re not accustomed to, because they are nervous/stressed due to their events, or because their immune systems are a bit compromised.

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The first thing you need to do is try to differentiate between a minor gastroenteritis and more serious illness. Nausea, vomiting, and diarrhea come with the territory, and may be accompanied by a low-grade fever. But a high fever (above 101 degrees F) should be a warning sign of a more serious illness. Similarly, vomiting lasting more than 48 hours, or leading to significant dehydration, is serious and you need to seek medical attention. Honestly, if it’s the week before a big competition seeing a physician is a good choice if you can.

Most of the time athletes get hit by minor gastroenteritis, the type that comes on quickly, makes you feel terrible for 1-2 days, and then goes away. From a performance standpoint, the impact can be huge. You’ll go 24-48 hours with little nourishment, you’ll lose significant amounts of fluid and electrolytes, and you’ll burn through energy stores you would rather save for race day.

So, if you get nailed by gastroenteritis the week of your race, is there any hope you can still have a good performance? The answer is yes, as long as you treat the illness like an endurance event.

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  1. Understand the goal: Gastroenteritis drains you of fluids, electrolytes, and energy. As an athlete with a goal coming up within a week, your goal is to minimize these losses. One mistake athletes make is to just curl up in a ball and wait for the illness to pass. If you’re not taking anything in to balance the depletion, the fluid, electrolyte, and energy deficits grow and grow. Your goal is to keep those deficits as small as possible, so you have a better chance of closing the gap once you feel better.
  2. Prioritize: Fluids are most important, followed by electrolytes, then calories. Not only are the consequences of dehydration and electrolyte imbalances more detrimental to health and performance than a lack of calories, they take longer to recover from. Your body is very good at packing glycogen into muscle cells and restocking liver glycogen. It takes longer to fully replenish fluid levels in tissues.
  3. Eat like an athlete: When you’re in a long training session or competition, you primarily consume fluids, electrolytes, and small portions of simple foods. When you’re suffering from gastroenteritis, you pretty much want to do the same thing, and you can even use some of the same foods. Water is an obvious choice, but simple sports drinks (essentially carbohydrate, electrolytes, and water) may be a good choice as well, if you can tolerate them. Salty foods can also be good, just keep your choices bland and simple (like crackers) when you’re nauseas. Most important, you should be consuming something regularly and frequently, just like during an endurance event.

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When you finally start feeling human again, you know the worst is over; but there’s still work to be done. Now you have to try to replenish what you’ve lost. Remember that your gut is still irritated; so don’t overwhelm it with huge quantities of complex foods. Continue eating simple ingredients in small portions on a frequent basis. Ideally, if you have about 3 days between the end of a 24- to 36-hour bout of gastroenteritis and your event, you can have a strong performance. If you have more time than that, all the better. If less, be prepared for a slow day and understand that you may reach a point where dropping out is the right choice.

If all goes well, you could have a surprisingly great performance. Moderate and temporary weight loss is often a consequence of gastroenteritis, and even though most of that weight loss is from dehydration, some athletes are still able to experience weight-related improvements in performance. On the other hand, it’s not uncommon for athletes to start out feeling great, and then suffer a rapid decline. This is most likely due to fuel depletion, and it seems to happen more frequently for athletes in high-intensity events like criteriums, sprint triathlons, and cyclocross. Athletes who compete at a more moderate intensity for longer periods may be able to avoid this sudden feeling of emptiness by consuming calories early on in their events.

Gastroenteritis sucks, but like most things in life and sport, the worst thing you can do is throw up your hands and give up. Stay focused, work the problem, and be patient. Don’t give up; it’s not pleasant but there have been plenty of champions who have gone from puking to the podium in less than a week.

Jim Rutberg is a Pro Coach for Carmichael Training Systems, Inc. and co-author of seven books with Chris Carmichael, including the NYT Bestseller Chris Carmichael’s Food for Fitness, The Time-Crunched Cyclist, and The Time-Crunched Triathlete. To find out about CTS coaching and camps visit

7 Responses to “Coming Back from a Stomach Bug: Gastroenteritis Treatment for Athletes”

  1. Mandie on

    Thankyou for the article, it makes sense and I wish I’d read it earlier! I am a novice Triathlete and have a sprint Triathlon tomorrow morning. I’ve had diarrhoea since Thursday though not constant. Last proper food was Wednesday evening. So far I’ve eaten dry biscuits and toast. I’ve drunk plenty but only water and black tea. Should I still compete or pull out? What should I eat today if aiming to compete still?

  2. Willem on

    Thanks for the article. Currently I’m that guy curled up in bed, only to get up to vomit and then snacking on plain bread or an apple, neither of which stays in long.

    I would love to compete in my half marathon this Sunday, but right now I can’t imagine I will.

    • Mandie on

      William I’m certainly no expert but I would think the Apple may be too fibrous and may not be helping? Try clear liquids, bland foods and possibly electrolytes in form of sports drinks? Hope you feel better soon

  3. Brian Klein on

    Good article. Most of the ‘average’ (using USATF recent numbers) athletes would probably just throw in the towel but for the people who spend so much time training that’s when you have the big choice to make.

    I ended up running a 1/2 marathon today mid-gastroenteritis (hit 36hrs since first ‘symptoms’ as I woke up for the race). No food in 36hrs and little liquids, but it was the 2nd part of a 3 part series, and since I was winning after the first I just wanted to try and keep myself in the running for the ‘TripleCrown’. With 6min of my time devoted to a porta-potty at mile 8, I was thus quite happy with a 1:31 finish time (14min off my PR).
    However, my body does hate me right now, and if I don’t manage to win the ‘TripleCrown’, I’ll be pretty pissed at my immune system. Only need to run a 1:20 in the last race so the potential is there.

    Thanks for the article!

  4. Steve Rush on

    Great job on the article. Josh, never heard that but makes sense. Another more aggressive way to settle the GI system is to take Imodium ( but not in excess, tricky to balance correctly) early to stop the diarrhea. You can also see if your Doctor will give you a few Zofran oral dissolvable tablets to have. Test it first when you’re well to make sure you tolerate it. Then if you are sick you can take it as a dissolvable tablet on your tongue to reduce or stop the nausea. This will allow you to begin to rehydrate and eat earlier. I agree with pushing sports drinks early, diluted if necessary. Two-3 days of clear urination prior to competing hopefully signal you have done your best. Besides just feeling depleted, lightheadedness should be an important indicator to not compete, or withdraw if you began the event.

  5. Joshua Clark, RN on

    Try charcoal.

    One of the best ways to combat, both before and during, a stomach bug is using an all natural remedy, like charcoal. It is super-absorbent, easy to find at your local health food store and it is fast acting, within an hour or two.
    What charcoal does is it soaks up whatever is bugging (pun intended) your stomach, decreasing your nutrient absorption, but more importantly decreasing normal signs and symptoms of gastroenteritis. Emergency rooms across the nation use charcoal as standard protocol for overdose patients for the same sponge-like reasoning, it gets rid of stuff fast.
    Mix a typical dose, 2-3 tablespoons, with your favorite fruit juice, water becomes very gritty and tasteless, and bottoms-up. One word of caution, it leaves a delightful appearance that you’ve been kissing a campfire, so make sure to brush your teeth before resuming daily activities. Best of luck to all of the sick-o’s that have to race, hope this helped a little.


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