Introduction

Introduction

Nausea is a subjective sensation that is difficult to define. It is an unpleasant feeling in the abdomen, often associated with the sense of being ill, a lack of appetite and the urge to vomit.
Early satiety is the feeling of fullness after ingesting a small amount of food or drink.
Vomiting is the forcible expulsion of stomach contents through the mouth.
Retching is a strong, belching-like, rhythmic movement in the oesophagus without vomiting.
Regurgitation is the passive return of gastric contents to the oesophagus and potentially the mouth; this is not associated with nausea.

Nausea and vomiting often (but not always) occur in combination.
Nausea and/or vomiting may be accompanied by salivary discharge, pallor, sweating, tachycardia, and the urge to defaecate.

Nausea and/or vomiting have a highly negative effect on quality of life. Persistent symptoms of nausea and/or vomiting may lead to a reduced intake of food and fluids and ultimately to dehydration, metabolic dysfunction (impaired renal function, hypokalaemia, metabolic alkalosis), malnutrition, exhaustion, haematemesis caused by oesophageal lacerations (Mallory-Weiss syndrome) or aspiration pneumonia. It may also lead to being unable or unwilling to take medication, and discontinuation of radiotherapy or chemotherapy.