In British English, it seems, people are said to "come out in a rash."
In the United States, the usual expression is "break out in a rash."|
British and American examples, respectively, from the Web:
But Mr Davis is now in talks with his Exeter solicitors to take his six-year battle for damages to the European Court of Justice. Mr Davis claims he first became ill in 1996 when he came out in a rash from which he has never recovered.There are British examples on the Web of "break out in a rash," too, and it appears in at least one British dictionary (though more British dictionaries list "come out in a rash"). In a quick Web search, I didn't see any American "come out in a rash" examples.
(March 17, 2003)