Ethephon (2-chloroethylphosphonic acid) is a generally used plant growth regulator, but the data on its toxic effects, especially in humans, are very limited. This study was conducted to describe the clinical characteristics, management, and outcomes of patients exposed to products containing ethephon. We performed an 8-year retrospective study using data from the Ramathibodi Poison Center database (2013–2020), which included 252 patients. Most patients were male, with a median age of 32 years. Almost all patients were exposed through ingestion, mainly in unintentional circumstances. The clinical presentations included local effects, gastrointestinal (GI), neurological, and respiratory symptoms. Some patients required hospital admission; specifically, seven patients received inotropic drugs, and six were intubated with ventilator support. Most patients had either no or only minor clinical effects. However, six patients experienced moderate/severe effects, and two patients died. Age, intentional exposure, and the presence of initial neurological symptoms could prognosticate moderate to fatal outcomes. In conclusion, exposure to ethephon predominantly resulted in no or minor effects, and GI symptoms were the most common clinical manifestation. The cholinergic toxic syndrome was not frequently observed. The mortality rate was very low. Patients presenting with factors associated with worse outcomes should be monitored closely for clinical deterioration and appropriately managed.