7 Reasons Why You Feel Nauseous After Working Out

If you feel nauseous after working out, you are not alone. The cause often comes down to how your body responds to a few key things: dehydration, what and when you eat and drink, bouncing movements, low blood sugar, heat exposure, and overexertion.

Jump to Key Takeaways.

1. Dehydration

Fluids and electrolytes (charged minerals like sodium and potassium) are lost during sweaty workouts. If you don’t replace them, you may become dehydrated and develop symptoms such as nausea, dizziness, or stomach cramps.

Hot or humid weather raises the risk, especially during workouts that induce heavy sweating or if someone isn’t well-hydrated before exercising. To help ensure you are not underhydrated before exercise, drink water consistently throughout the day, not just during exercise.

2. Exercising on a Full Stomach

Eating a large meal just before exercise can trigger nausea. This happens because blood flow shifts away from your digestive organs to fuel working muscles. Also, undigested food in your stomach may be jostled around during physical activity, leading to gastrointestinal (GI) problems.

While meal-timing before exercise is individual, a good rule of thumb is to finish large meals two to three hours before working out.

3. High-Impact Activity (Bouncing)

The bouncing motion of high-impact activities like running, jumping, or doing explosive plyometrics can upset your stomach, especially if it’s full. Jarring up-and-down movements during cardio workouts can cause motion sickness in some people.

If you have trouble with nausea during activities with bouncing motion, choose low-impact cardio exercises like walking, cycling, swimming, using an elliptical, or rowing machine.

4. Low Blood Sugar

Working out on an empty stomach can trigger low blood sugar (hypoglycemia). Glucose is your body’s main fuel source during exercise. When levels drop too low, nausea may follow. To help prevent low blood sugar, eat a light snack 30 to 60 minutes before you start exercising.

5. Overexertion

Going too hard, too fast during exercise can upset your stomach, as can endurance exercise such as long-distance running or cycling. High-intensity workouts or prolonged exercise may trigger exercise-induced gastrointestinal syndrome (EIGS), which often causes nausea.

6. Heat Exposure

Exercise produces internal heat, which the body works to dissipate. Exercising when it’s hot and humid further strains your body’s cooling system. As more blood is sent to your skin to release heat, less reaches your gut. This shift in blood flow can cause nausea or vomiting.

To prevent heat illness, avoid exercising outdoors when temperatures, humidity, or the ultraviolet (UV) index are high.

7. Effects of Sports Drinks or Energy Snacks

If you drink sports drinks or use energy gels or bars, you may develop nausea due to sensitivity to the sugars (such as fructose or lactose) or other ingredients in them. Also, sports drinks that are high in sugar and electrolytes may trigger nausea.

On the other hand, replenishing only with plain water during endurance exercise can lead to low sodium levels (hyponatremia), as you lose salt through sweat. Nausea is a symptom of hyponatremia.

How to Get Immediate Relief

If you start to feel nauseous during or after exercise:

• Stop your workout and rest in a cool, shaded, or air-conditioned space.
• Sip water or an electrolyte drink without gulping.
• Take deep, slow diaphragmatic breaths or lie down with your legs slightly elevated.
• Don’t eat anything heavy until your stomach settles.

How You Can Prevent Nausea in Future Workouts

Most causes of exercise-induced nausea can be managed with a few simple strategies:

• Hydrate steadily throughout the day, not just before or during your workout.
• Avoid large meals within two to three hours of exercise.
• Eat a light snack before your workout if exercising on an empty stomach tends to make you nauseous.
• Build intensity gradually to prevent overexertion.
• Choose cooler workout times (early morning or evening) and wear breathable, sweat-wicking clothes in hot or humid weather.
• Keep a log of your exercise habits to identify nausea triggers. Note what you ate, when you exercised, the weather, type of activity, etc.

When to See a Healthcare Provider

Mild nausea after a tough workout is usually nothing to worry about. But if it happens often, keeps you from exercising, or comes with more serious symptoms (like chest pain, vomiting, or fainting), talk to a healthcare provider.

Key Takeaways

• Dehydration, big meals, hot weather, low blood sugar, bouncing activities, energy drinks and snacks, and pushing too hard can make you feel sick to your stomach during or after exercise
• Making small changes to your eating, drinking, and exercise habits can help.
• If you feel nauseous, stop, rest, sip water, and cool down.