break out in a cold sweat
To begin sweating because one is nervous or frightened. Any time I have to get blood drawn, I break out in a cold sweat the minute I get to the doctor's office. I used to be terrified of driving, but now I can get behind the wheel without breaking out in a cold sweat!
break out in a cold sweat
Lit. or Fig. to become frightened or anxious and begin to sweat. I was so frightened, I broke out in a cold sweat. Larry broke out in a cold sweat when he cut his hand.