As soon as he started eating, his mouth began to burn, his eyes began to water, and his whole face became as red as the fruit.

他一开始吃，嘴巴就开始发烫，眼睛开始流眼泪，整个脸变得像水果一样红。

youdao

Be careful not to burn your mouth.

小心别烫痛嘴。

《新英汉大辞典》

He picked many chiles and began to eat them but the chiles were hot and his mouth and tongue began to burn.

他摘了很多辣椒开始吃了起来，辣椒很辣，他的嘴和舌头都被辣得发起烧来。

youdao

In another incident, a mother said that cafes and restaurants had refused to warm up baby food for her daughter because the hot food might burn the 14-month-old girl's mouth.

BBC: UK Politics