gastroenteritis; stomach flu
Commonly used in everyday conversation to refer to acute gastrointestinal illness with symptoms like vomiting and diarrhea. The medical term 胃腸炎 is more formal.
See also: 胃腸炎
I've been laid up with stomach flu since yesterday.
Stomach flu is going around, so please be careful.
More formal medical term for gastroenteritis. 胃腸風邪 is a colloquial, less clinical expression.
Compound of 胃腸 (stomach and intestines) and 風邪 (cold), literally 'stomach-intestinal cold'. The term likens gastrointestinal symptoms to those of a common cold.