Eosinophilic oesophagitis – EoE for short – is a chronic inflammatory condition of the oesophagus, also known as ‘asthma of the oesophagus’. This immune-mediated condition is clinically characterised by oesophageal dysfunction and histologically by eosinophil-predominant inflammation. The most common symptoms in adults are dysphagia (difficulty swallowing, sometimes accompanied by pain when swallowing), bolus obstruction or impaction with an associated gag reflex, and chest pain.

However, the condition has only come increasingly into the focus of medical attention since the 2000s. EoE should not be confused with other systemic and local causes of immune-mediated inflammation of the oesophagus, such as gastro-oesophageal reflux disease (GERD), eosinophilic gastroenteritis, parasitic infections or Crohn’s disease.

Eosinophilic oesophagitis probably first emerged in the 1970s. It was not recognised as a distinct clinical entity in the USA and Europe until 1993/94, when it was described independently by Stephen Attwood and Alex Straumann. Subsequently, the condition was rapidly documented in Australia and, since then, in virtually all industrialised countries worldwide. The prevalence of EoE is steadily increasing. Roughly estimated, there is currently one patient with diagnosed EoE for every 2,500 to 4,000 inhabitants in countries with a Western lifestyle (prevalence = 25–40 patients per 100,000 inhabitants). To put it more clearly, there is one patient in every medium-sized village. The figure is likely to be significantly higher (perhaps even considerably higher) if previously undiagnosed cases are taken into account. EoE can occur at virtually any age, but usually begins between the ages of 10 and 40.