rear one's head

• rear one's ugly head (often used in this form)

rear one's head (third-person singular simple present rears one's head, present participle rearing one's head, simple past and past participle reared one's head)

1. (literally) To raise one's head.
2. (idiomatic) To appear and cause problems or stress, especially at an inopportune time (said of something or [rare] someone that is undesirable or unwelcome).
   • 2021 October 6, Greg Morse, “A need for speed and the drive for 125”, in RAIL, number 941, page 53:

     One problem that reared its head in 1983 would prove more difficult to solve, with the heat that summer leading to a number of engine failures.

   • 2024 January 13, Callum Matthews, “Newcastle United 2-3 Manchester City”, in BBC Sport‎^[1]:

     For large parts of this season City have been far from the level that saw them win the Treble last season, especially defensively. Those issues reared their head again, and will lead to questions about the summer recruitment, with some poor defending for both Newcastle goals.

• raise one's head

• “rear one’s head”, in Lexico, Dictionary.com; Oxford University Press, 2019–2022.
• “rear its ugly head” in Longman Dictionary of Contemporary English, Longman.
• “rear its ugly head”, in Cambridge English Dictionary, Cambridge, Cambridgeshire: Cambridge University Press, 1999–present.