An upset stomach can happen due to indigestion, a viral infection, food poisoning, acidity, overeating, stress or eating contaminated food. Symptoms include nausea, bloating, stomach cramps, loose stools, gas, or a feeling of heaviness after meals. The right medicine depends on whether the main problem is acidity, diarrhoea, vomiting, or stomach pain. Doctors may use anti-acids for acidity, probiotics to promote digestion, oral rehydration fluids for loose motions, or anti-nausea medicines when vomiting is present. Many mild stomach problems improve with light meals, such as rice, bananas, toast and curd, along with plenty of fluids. Avoiding oily, spicy, and heavy foods for a short time may also help the stomach settle better. Antibiotics are usually not needed for simple viral stomach upset, and unnecessary use may sometimes worsen digestion. Fever, blood in stool, severe dehydration, black stools, persistent vomiting, or severe abdominal pain can indicate a more serious stomach problem and may need proper medical care.