take a turn for the worse
To worsen, often quickly or suddenly. We should get over to the hospital now—Uncle Jim's taken a turn for the worse and probably won't make it through the day. My day took a turn for the worse when I got that phone call.
take a turn for the worse
to start to get worse. It appeared that she was going to get well; then, unfortunately, she took a turn for the worse. My job was going quite well; then last week things took a turn for the worse.
take a ˌturn for the ˈbetter/ˈworse
become better/worse: The weather is taking a turn for the worse, I’m afraid.