expression, adverb
without thinking of the consequences; recklessly; heedlessly
Used when someone acts impulsively without considering what will happen afterwards. Often has a negative connotation.
彼は後先考えずに会社を辞めてしまった。
He quit his job without thinking of the consequences.
後先考えずに発言すると、後で後悔するよ。
If you speak without thinking of the consequences, you'll regret it later.