那“把肺都要咳出来了”用英语怎么说呢？还真有一种说法，叫 cough (one's) head off。
意思是指to cough intensely, as from an illness，因为疾病而剧烈咳嗽。看来外国人不说肺咳出来，而说“把头咳掉了”。
举个例子：
Natalie has still been coughing her head off, so I don't think the antibiotic you gave her has helped.
娜塔莉一直在咳嗽，所以我认为你给她的抗生素没有帮助。
还有一种说法叫做 coughing fit，意思是 a sudden period of coughing，“一阵猛咳”。
举个例子：
However, when not in a coughing fit, the patient does not experience trouble breathing.然而，当不咳嗽时，患者不会出现呼吸困难。