without thinking of the consequences; recklessly; heedlessly
Used when someone acts impulsively without considering what will happen afterwards. Often has a negative connotation.
He quit his job without thinking of the consequences.
If you speak without thinking of the consequences, you'll regret it later.
Standard kanji spelling for this set phrase.
Kana spelling for the first part is common in everyday writing.
A set phrase combining 後先 (あとさき, 'before and after' or 'consequences') with the negative continuative form of 考える (かんがえる, 'to think'), literally 'without thinking of before and after'.