(used of something considered unpleasant) appear again after being hidden or forgotten: Political corruption has reared its ugly head again.

What does reared its head mean?

If you say that something unpleasant or embarrassing rears its ugly head or raises its ugly head, you mean that it occurs, often after not occurring for some time. There was a problem which reared its ugly head about a week after she moved back in.

Has reared its head again?

COMMON If something unpleasant rears its head or raises its head, it starts to appear or be active, often when it had stopped or been hidden for a period. Now the same ugly forces of racial hatred are beginning to rear their heads again. The familiar pattern of violence is raising its head once again in the region.