Why Do I Feel Nauseous After Working Out? Causes and Solutions Explained

Nausea after a workout can be caused by dehydration, working out hard on an empty or full stomach, or heat.

Common causes

• Dehydration.
• Exercising on an empty stomach or right after eating.
• Intense effort and blood being diverted from the gut.
• Heat.
• Low blood sugar or low sodium.

Prevention

• Eat a light snack 1 to 2 hours before.
• Drink water.
• Cool down gradually.

What to do now

Sit down, sip fluids and rest.

See a doctor

If nausea comes with chest pain, dizziness or confusion.

Mechanisms

During exercise, blood is diverted from the digestive tract to working muscles. Digestion slows, and the stomach may not empty properly, which can cause nausea. Intense effort also raises body temperature and adrenaline.

Common triggers

• Exercising too soon after a meal. Wait 2 to 3 hours after a large meal, or 30 to 60 minutes after a small snack.
• Dehydration or heat.
• Low blood sugar from not eating before a workout.
• Overexertion at high intensity.
• Drinking too much water quickly.
• Sports drinks and gels high in sugar.
• Medications, including NSAIDs.
• Sudden stopping after hard exercise, causing blood to pool in the legs.

Medical reasons

Heart issues, exercise induced asthma, acid reflux, low sodium or pregnancy can also contribute.

Prevention

• Eat a light, easy to digest snack (a banana or toast) 30 to 60 minutes before.
• Drink fluids regularly during exercise.
• Warm up gradually and cool down for 5 to 10 minutes.
• Avoid fatty or high fiber foods before a workout.
• Build intensity slowly.
• Exercise in cooler conditions.

What to do now

Slow down, stop and rest, sip water or an electrolyte drink and cool off. Sit or lie down with legs raised if dizzy. Ginger or peppermint may soothe.

Heat illness

Nausea with confusion, extreme fatigue, cramps, heavy sweating or very high temperature may be heat exhaustion or heat stroke. Get medical help.

See a doctor if

Nausea with every workout, with chest pain, shortness of breath, dizziness or fainting. Seek emergency help for chest pain or fainting.

Why exercise can cause nausea

During hard exercise, blood flow shifts from the digestive system to working muscles, which slows digestion and can cause nausea, especially if you ate recently. Other causes are dehydration, low blood sugar, high temperatures, too much intensity too soon, drinking large amounts of water or sports drinks quickly and stopping abruptly, which lets blood pool in the legs. Exercise associated hyponatremia from overdrinking is a rare cause. Heat illness is another cause.

Prevention

Eat a light snack of carbohydrates 1 to 2 hours before and avoid large or fatty meals 2 to 3 hours before exercise. Warm up for 5 to 10 minutes and cool down gradually. Sip fluids steadily, stay cool and build intensity over weeks. If nauseous, slow down, sit and sip a little water. See a doctor if nausea comes with chest pain, shortness of breath, dizziness, confusion or if it happens with every workout, which can signal heart or other conditions.

Based on data from the American College of Sports Medicine and the Mayo Clinic