Closed comedones pop up after pulling an all-nighter.
Tips
usage
Beauty-community usage. The original meaning of 闭口 is the verb 'to close one's mouth' — in skincare it's short for 闭口粉刺 (closed comedone). Pair term: 黑头 (blackhead / open comedone).
mistakes
In a skincare context 闭口 is always a noun. Don't confuse with the idiom 闭口不言 'to refuse to speak'.