Nausea refers to the uncomfortable feeling preceding vomiting, though vomiting does not always occur afterward. Certain foods, contaminated foods and eating too quickly may contribute to nausea. In some cases, nausea indicates a serious underlying condition, such as food poisoning or an ulcer. If your nausea is severe, recurrent or long-lasting, seek guidance from your doctor.

Food poisoning, or food-borne illness, happens after ingesting food contaminated with toxins such as bacteria. According to the University of Maryland Medical Center (UMMC), 75 million people are affected by food poisoning annually and nausea is a common primary symptom. In addition to nausea, you may experience headache, body aches, fever, diarrhea, abdominal pain or cramping and vomiting. Most mild to moderate cases of food poisoning in healthy adults resolves itself in a matter of days. People with weakened immune systems, elderly people and children are more susceptible to severe food poisoning symptoms and may require medical attention or hospital care. If diarrhea or vomiting accompany nausea, be sure to replenish fluids by drinking plenty of water or sports beverages containing electrolytes to avoid dehydration.

Peptic ulcers, or erosions in the stomach lining or the top of the small intestine, commonly lead to mild nausea after eating. According to the UMMC, most people develop peptic ulcers in response to a bacterial infection. Excessive alcohol consumption, regular use of aspirin or other anti-inflammatory medications, smoking and serious illness may also trigger or exacerbate peptic ulcer symptoms. Additional symptoms may include uncomfortable fullness during and following meals, hunger, an "empty" feeling several hours after a meal and pain in the upper abdomen. More serious potential symptoms include bloody diarrhea, chest pain and unintentional weight loss. Peptic ulcer treatment generally involves medications that reduce harmful bacteria. Eating smaller meals, avoiding certain foods known to influence symptoms such as spicy or high-fat foods, and relaxation techniques may also help prevent or alleviate symptoms.

Nausea after eating may stem from indigestion. Also known as dyspepsia, indigestion refers to a set of symptoms that arises when the digestive process is somehow hindered. Additional symptoms of indigestion may include abdominal pain, bloating, belching or gas. According to the Mayo Clinic, common causes of indigestion include overeating, consuming fatty or greasy foods, emotional stress and drinking carbonated beverages. In some cases, indigestion develops in response to a more serious underlying condition such as gallstones or stomach cancer. Indigestion is often treated through dietary lifestyle changes, stress reduction or over-the-counter medication. If an underlying condition causes nausea or other indigestion symptoms, diagnosis and treatment for that condition is crucial. Since nausea may indicate a variety of conditions aside from indigestion, seek your doctor's guidance for best potential results.