"Wow, you are on fire!"，初次听到这句话，会不会潜意识里以为自己身上着火了呢？
on fire的确有"着火"的意思，比如：The house is on fire. 房子起火了！
但是on fire不仅仅有“着火”的意思，它还可以表示“情绪饱满、热情高涨、高水平发挥”，
比如说：
Man, you are on fire! 哥们儿，你状态真不错！[666]
You guys were on fire in the last quarter. 你们最后一节真是打得太棒了。
“上火”英语怎么说？
“上火”这一词儿，对不了解中国文化的外国友人来说，那是难上加难懂呀，
一激动，可别说成“I'm on fire” ，还是要’体谅下‘对方的理解情绪。[偷笑]
那怎样表达“上火” 比较合适呢?
英语中有这么一个词：heatiness
先借助下中医理论言辞看看：
a characteristic of certain foods or stimulants said to cause emotional or physical reactions associated with temper, fever, passion, excess, or true heat.（From Chinese culture and medicine.）
一种食物或刺激物的特性，据说能引起情绪或身体上的反应，与脾气、发烧、情绪、过量或热有关。（参考中医理论）嗯...解释的到位。[小鼓掌]
heatiness的形容词形式是heaty：
You're heaty. 你火大（上火）。
其属于中医术语，如果有强迫症，需要给对方解释清楚下的话 ，我们可以这样表达下中医概念：
"Shanghuo(heatiness)" is a unique concept in traditional Chinese medicine.
“上火”是传统中医中一个特有的概念。
Traditional Chinese medicine categorises food as凉lèung (“cooling”),热气yiht hei (“warming”) and neutral–and practitioners use the nature of the foods to balance the body's yin（ 阴）and yang （阳）[无辜笑]
传统中医把食物分为凉性、热性和中性——医生们则用这些食物的特性平衡人体的阴阳。
以下为拓展，参考了解下吧 [听歌]
TCM describes heaty foods as having the ability to warm and improve circulation, dispel cold and stimulate the body. When these foods are taken in excess (yang is greater than yin, your body will generate too much heat), heatiness is caused, resulting in symptoms such as fever, sore throat, mouth ulcers, acne, excessive thirst, redness of the skin and irritability.
中医认为，热性食物具有保暖、促进血液循环、驱寒和激发身体的功能。当这些食物摄入过量（体内的阳压过阴时，你的身体会产生过多的热气），会导致“上火”的现象，引发发烧、喉咙痛、口腔溃疡、*疮痤**、极度口渴、皮肤发红和易怒等症状。