If nausea is associated with profuse watery salivation, vomiting soon follows. Patients with food problems will often report chronic low-grade nausea. They often wake up feeling sick and describe a variety of uncomfortable abdominal sensations as the day proceeds. Their nausea is not related to eating any one food, but disappears when complete diet revision is successful. Bloating is distention of the abdomen from excess gas in the digestive tract.
Gas can accumulate from the fermentation of food materials and from air-swallowing.
Food allergy can cause rapid, dramatic bloating by a mechanism that is not understood but probably involves increased blood flow through the small intestine with transfer to blood gases. Constipation consists often decreased frequency of bowel movement, often with harder stools that are difficult to pass. Skipping bowel movements for several days will usually result in abdominal bloating and tenderness. Constipation suggests a slowing of peristalsis, with accumulation of feces in the colon. Often the muscle of the colon will contract in a spastic manner blocking the passage of stool.