Nausea can be caused by various factors, including: 1. Viral or bacterial infections 2. Motion sickness or vertigo 3. Side effects of medications 4. Pregnancy 5. Anxiety or stress 6. Digestive issues like acid reflux or gastritis 7. Food intolerance or allergies 8. Migraines or headaches 9. Overeating or eating spoiled food If you experience persistent or severe nausea, it’s important to seek medical advice to identify the underlying cause and receive appropriate treatment.