Experiencing slight fatigue or soreness after running is normal, but nausea is usually a sign that something is out of balance. Common factors that contribute to nausea after running include fluid imbalances, low blood sugar and overexertion.
Eating foods that are hard to digest or that irritate the gastric lining can have similar results. Pacing yourself and watching your food and water intake can prevent nausea after running from occurring in many cases, but if it doesn't, consult a doctor to rule out an underlying medical disorder.
Nausea after running means something is wrong. Check your fluid and food intake before a run and don't overexert yourself.
Dehydration and Overhydration
Dehydration can contribute to a feeling of nausea, but overhydration can also cause similar symptoms. To find the right balance of water, weigh yourself before and after you run. The weight you lose will be mostly water weight, so weighing yourself will give you an idea how much water you need to drink. Start hydrating the night before a vigorous run.
Drink 8 fluid ounces of water, 20 to 30 minutes before you run, says ACE Fitness. Take small sips of water during your run, waiting until after you finish running to fully hydrate.
If you are sweating a lot while you run, replacing water with a sports drink enhanced with electrolytes can help you hydrate more effectively; however, you should avoid drinking beverages that are high in sugar and salt, as they can be hard to digest and often lead to nausea or other gastrointestinal issues.
Not Enough or Too Much
Not eating enough food or skipping a meal can make your feel dizzy and nauseous after running because your body is lacking the fuel to function properly. On the other hand, eating too much too soon before running can put a strain on your digestive system, leading to cramps and nausea.
What you eat also plays a role. If you consume hard-to-digest foods or substances that irritate the gastric lining, such as caffeine, alcohol or aspirin, it can have similar results. Eat a meal that is mostly carbohydrates with small amounts of lean meat and fats. Avoid consuming too much protein, fiber, sugar or fats. Mayo Clinic recommends not eating in the two hours before a run.
Pushing Yourself Too Hard
Nausea is a common experience for runners who participate in endurance events, such as marathons and triathlons, says the National Academy of Sports Medicine. Even if you aren't participating in a long race, you may be working beyond your limits.
When you do that, you not only deplete your energy, you build up waste products, primarily lactic acid. If you are out of shape, your body may not be able to process getting rid the waste products quickly enough, which can lead to nausea.
In addition to following proper eating and drinking habits, pace yourself while you are working out. Avoid running to the point where you feel like you are going to be sick. If you are a more seasoned runner trying to increase the duration or intensity of your regimen, do so slowly and gradually.
The Underlying Issues
While controlling what you eat and drink and pacing yourself can get rid of post-run nausea in many cases, other underlying issues could be causing the problem. Medications, gastrointestinal problems and balance issues can all have nausea as a side effect or symptom.
If you are on medication, talk to your doctor to ensure nausea is not a side effect. Running could just be making the nausea more noticeable. If you are not taking medication and feel nauseated consistently, despite taking preventive measures, consult your doctor to rule out a gastrointestinal or other disorder.