Feeling like throwing up after a run—or actually doing it—is not fun or uncommon. Nausea or vomiting during or after a run can happen for a few reasons.
Most of the time—while unpleasant—it's not serious and is usually something you can manage. If you experience nausea after running while training for a race, consider it an opportunity to determine the cause and fix it before your marathon.
Reasons for Nausea After Running
Even if you usually have an iron stomach, intense exercise can reduce blood flow to your digestive system. The result is a queasy feeling, especially when paired with these common causes of post-run nausea.
Pre-Run Meal Timing
If you ate less than an hour before your run, you may feel nauseous and even throw up whatever you ate. That's because it can take up to two hours for food to move out of the stomach.
It's OK to have a light, healthy snack about 90 minutes to two hours before your run. Try to eat something easily digestible, such as toast with peanut butter or a banana. If you eat something that takes longer to digest, like fatty or fried foods, you should wait at least 2 hours before running.
Dehydration
Nausea after running is an early symptom of dehydration, which occurs when the body doesn't have enough water in it to function well. Dehydration can impact your heart rate, blood pressure, and temperate, which can all trigger nausea when associated with issues.
Be sure you're fully hydrated before you start running and drink when you feel thirsty on your run. In general, that means about 6 to 8 ounces of fluid if you're running faster than an 8-minute-per-mile pace, and 4 to 6 ounces of fluid every 20 minutes for those running slower. However, also be aware that drinking too much water can cause nausea.
During longer workouts of 90 minutes or more, some of your fluid intake should include an electrolyte sports drink to replace lost sodium and other minerals. Don't forget to rehydrate with water or a sports drink after your run, too. If your urine is dark yellow, you're dehydrated and need to keep rehydrating. Aim for urine the color of light lemonade.
Some runners don't drink during their runs because they don't have access to water if running outdoors. An easy solution is to run with a hand-held water bottle or belt carrier made specifically for runners. If you don't like to carry water with you, plan your route so you have access to water fountains or a strategically placed water bottle.
Hot Weather
Use caution during hot and humid conditions. Even if you attempt to stay hydrated when running, 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 gel product while running, your nausea after running could be a reaction to the food or beverage. Some runners find their stomachs are sensitive to sugary 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.
To mitigate this issue, try making your own rehydration drink by adding 4 tablespoons of lemon juice, a couple of pinches of salt, and 2 tablespoons of honey to 16 ounces of water. Instead of energy gels, try dried fruit, nuts, or honey (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, moody and irritable, or slow to catch your breath. This feeling can be a sign that you are lacking some fitness for the pace you are running.
Avoid this problem by warming up before starting an intense run, and running at a pace you're ready for. (Tip: During a distance run, you should be able to talk while running.) Always increase your pace, distance, or time slowly and gradually—and never all three simultaneously.
What to Do When Nausea Strikes
If you feel like you might throw up after a run, sip water slowly, in case you are dehydrated. If heat is a likely culprit, get into an air-conditioned space as soon as possible to cool off.
Whatever the suspected cause may be, don't force yourself to continue running (although you should not skip your cooldown, as it may help you feel better). Rest. If you're still feeling sick or throwing up after several hours, consult a healthcare professional.
If your nausea after running is short-lived and you feel confident you know what caused it, you should be able to run again within a day or two. If the nausea was due to overexertion, scale back your intensity and warm up and cool down adequately.
If you think your pre-run meal or on-the-go nutrition was the culprit, experiment to see what foods and timing work better for you. It's always better to experiment when training to be comfortable during a race. Consider adding notes on nutrition to your training log so you can look for patterns and keep track of successes and failures.
Nausea Before a Run
If you're struggling with 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 feel 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, is a sign you should stay home and rest.
Nausea on Race Day
If you're about to line up for your race and aren't feeling well, your nerves may be kicking in. It's not unusual to feel anxious about a race, especially after all the hard work you've put in to train and prepare, but all of that training is what will ultimately get you through it.
