How to say "relapse" in Japanese

• 再発さいはつJLPT N1approx.Common
  noun, suru verb, intransitive verbCovers the medical or problem sense: a disease, symptom, or undesirable situation that returns after it seemed cured or resolved. Typical in talk of illness, addiction, and recurring troubles.
  １９５５年ねんにガンが再発さいはつし、彼女かのじょは１９５６年ねんに４２歳さいで亡なくなった。↗

  In 1955, the cancer returned and she died in 1956 at the age of 42.
• 逆戻りぎゃくもどりCommon
  noun, suru verb, intransitive verbMeans doubling back or reversing to an earlier state, often a worse one, e.g. progress on negotiations or reform undone. As 'relapse' it is figurative; for returning to bad habits or old behavior 後戻り is often the better fit.
• 後戻りあともどりCommon
  noun, suru verb, intransitive verbMeans going back to a previous, usually bad state or to old ways, and suits relapse into bad habits or former behavior. It is really 'regression or returning to a bad state', not a medical recurrence.

Use 再発 for a recurrence of a disease, condition, or problem after improvement; use 「逆戻り」 or 「後戻り」 for going back to a former, usually worse, state or behavior.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• 再発さいはつreturn
• 逆戻りぎゃくもどりretrogression
• 後戻りあともどりregression