antidepressant onset of action

Last reviewed 01/2018

  • data using weekly or daily rating demonstrate that maximum improvement with antidepressant treatment occurs during the first 2 weeks, with some improvements within the first 3 days (1)
    • implication for clinical practice is that current evidence suggests it would be more accurate to say to patients that in 90% of cases substantial improvement occurs within the first 2 weeks, but that benefit continues to build up over several weeks


  1. Mitchell AJ. Two-week delay in onset of action of antidepressants: new evidence. The British Journal of Psychiatry (2006) 188: 105-106.
  2. Warwick Medical School (August 2007).Clinical Pharmacology Newsletter.