Feeling sick to your stomach is called nausea. You may feel like you want to throw up. When you empty the contents of your stomach, you throw up or vomit. You may have only one of these signs or both at the same time. Most often, they will stop on their own. Feeling sick to your stomach or throwing up may be a sign of some other illness. You may not feel like eating or drinking. You may also have pain in your belly or lose weight. If these signs last a while, you may need testing to find out the cause.