relapse

/rɪˈlæps/
verb
  1. To return to a previous, usually worse, condition or state after a period of improvement.
    • He relapsed into his old habit of staying up too late.
    • The economy could relapse into recession if the reforms fail.
    • If you stop taking the medication, you might relapse into depression.
noun
  1. A return to a previous, usually worse, condition or state after a period of improvement, especially in health or behavior.
    • After months of feeling better, she suffered a relapse of her illness.
    • He had a relapse into his old smoking habit after quitting for a year.
    • The patient's relapse was unexpected and required immediate medical attention.