Why You Might Feel Nauseous at the End of a Run

Man resting with hands on knees during a run
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Nausea during or after a run can happen for a few different reasons. It's not fun, but it's usually something you can manage. If you get nauseous after running while training for a race, look at it as a blessing. You can determine the cause and fix it before the event.

Why You Feel Sick to Your Stomach

Even if you usually have an iron stomach, intense exercise can reduce the flow of blood to your digestive system. The result is that queasy feeling, especially when paired with these common causes of post-run nausea.

Your Pre-Run Meal

If you ate less than an hour before your run, that's too close to your workout and it's possible that you'll feel nauseous and even throw up whatever you ate. It's OK to eat a light snack about 90 minutes before your run. Try to eat something that is easily digestible, such as some toast with peanut butter or a banana. If you eat something that takes longer to digest, like fatty or fried foods, you should give yourself at least two hours before running.

Dehydration

Nausea is an early symptom of dehydration. Be sure to drink water before your run. While running, obey your thirst and drink when you are feeling thirsty. In general, that means about 6 to 8 ounces of fluid for runners running faster than an 8-minute/mile pace, and 4 to 6 ounces of fluid every 20 minutes for those running slower than that. But also be aware that drinking too much water can also cause nausea.

During longer workouts of 90 minutes or more, some of your fluid intake should include a sports drink (like Gatorade) to replace lost sodium and other minerals. And don't forget to rehydrate with water or a sports drink after your run. If your urine is dark yellow after your run, you're dehydrated and need to keep rehydrating. It should be a light lemonade color.

Some runners don't drink during their runs because they don't have access to water if they're running outdoors. An easy solution to that problem is to run with a hand-held water bottle or belt carrier made specifically for runners. If you really don't like to carry water with you, plan your route so that you have access to water fountains or a strategically placed water bottle.

Hot Weather

Use caution when the conditions are extremely hot and humid. Even if you attempt to stay hydrated when running in those conditions, you could still be at risk for nausea, dehydration and other heat-related illnesses. Run indoors or reduce the distance or intensity of your workout to help you stay safe when running in the heat.

Your Sports Drink or Energy Gel

If you've consumed a sports drink or energy gels while running, your nausea could be a reaction to them. Some runners find that their stomachs are sensitive to sugary-sweet sports drinks or energy gels. This is often the case if you combine a drink and a gel. Together, they provide too much sugar for your stomach to handle. Other options:

  • Make your own rehydration drink by adding four tablespoons of lemon juice, a couple pinches of salt, and two tablespoons of honey to 16 ounces of water.
  • Instead of energy gels, try dried fruit, nuts, or honey (which is available in portable Honey Stinger packets).

Overdoing It

Another possible cause of nausea during or after running is that you simply ran too hard and overexerted yourself. You may also feel more tired than usual, or moody and irritable, or slow to catch your breath.

Avoid this problem by making sure you're warmed up before starting an intense run, and running at a pace that you're ready for (you should be able to hold a conversation while running, if you're doing a distance run). Always increase your pace, distance, or time slowly and gradually, and never all three at once.

What to Do If You Feel Nauseous After a Run

If you feel like you might throw up after a run, sip some water very slowly, in case you are dehydrated. If heat is a likely culprit, make sure you get in air conditioning as soon as possible to cool off. Whatever the suspected cause may be, don't force yourself to continue running or do another activity (although you should not skip your cool-down, as it may help you feel better). Just rest. If you're still feeling sick or throwing up after several hours, you may want to consult a healthcare professional.

Your Next Run

If your post-run nausea was short-lived, and you feel pretty confident that you know what caused it, you should be able to run again within a day or two. If your nausea was due to overexertion, scale back your intensity, and be sure to warm up and cool down adequately.

If you think your pre-run meal or on-the-go nutrition was the culprit, you will probably need to experiment to see what foods and what timing work better. It's always better to do this when you are training so that you will be comfortable during a race, if you have one planned. Consider adding notes on nutrition to your training log, so you can look for patterns and keep track of successes and failures.

If You Feel Nauseous Before a Run

If you're suffering from nausea, vomiting, or some other gastrointestinal discomfort even before you lace up your shoes, it's best to skip your run. The "above the neck/below the neck" rule is a good guideline: If you are feeling unwell, but your symptoms are all above the neck (runny nose, sore throat), you can run if you feel up to it. Below the neck symptoms, including nausea, are a sign that you should stay home.

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