Signs and symptoms of dumping syndrome generally occur right after eating, especially after a meal rich in table sugar (sucrose) or fruit sugar (fructose). Signs and symptoms might include:

• Feeling bloated or too full after eating
• Nausea
• Vomiting
• Abdominal cramps
• Diarrhea
• Flushing
• Dizziness, lightheadedness
• Rapid heart rate

Late dumping syndrome starts one to three hours after you eat a high-sugar meal. The signs and symptoms develop that long after you eat because your body releases large amounts of insulin to absorb the sugars entering your small intestine. The result is low blood sugar.

Signs and symptoms of late dumping syndrome can include:

• Sweating
• Flushing
• Dizziness, lightheadedness
• Weakness
• Rapid heart rate

Some people have both early and late signs and symptoms. And dumping syndrome can develop years after surgery.

Stomach and pyloric valve

In dumping syndrome, food and gastric juices from your stomach move to your small intestine in an uncontrolled, abnormally fast manner. This is most often related to changes in your stomach associated with surgery.

Dumping syndrome can occur after any stomach surgery or major esophageal surgery, such as removal of the esophagus (esophagectomy).

Gastric bypass surgery

Surgery that alters your stomach can increase your risk of dumping syndrome. These surgeries are most commonly performed to treat obesity, but are also part of treatment for stomach cancer, esophageal cancer and other conditions. These surgeries include:

• Gastrectomy, in which a portion or all of your stomach is removed.
• Gastric bypass surgery (Roux-en-Y operation),which is performed to treat morbid obesity. It surgically creates a stomach pouch smaller than the stomach, meaning that you're no longer able to eat as much as you once did. It connects the small intestine to this pouch in the form of a gastrojejunostomy.
• Esophagectomy, in which all or part of the tube between the mouth and the stomach is removed.