American Board of Internal Medicine (ABIM) Certification Practice Exam

What is the minimum duration considered for an adequate antidepressant trial?

1. 4 weeks at a therapeutic dosage

2. 6 weeks at a therapeutic dosage

3. 8 weeks at a therapeutic dosage

4. 10 weeks at a therapeutic dosage

The correct answer is: 6 weeks at a therapeutic dosage

An adequate trial of an antidepressant is generally recognized as lasting a minimum of 6 weeks at a therapeutic dosage. This duration is essential to allow for the gradual onset of the therapeutic effects of most antidepressants, which typically does not manifest until after several weeks of consistent use. The reason 6 weeks is specifically considered the minimum is tied to pharmacodynamics: many antidepressants require time to build up to their effective concentration in the body. Additionally, clinical guidelines and studies suggest that significant clinical improvement usually occurs around this timeframe, prompting clinicians to reevaluate the effectiveness of the treatment. While responses can vary among patients and some may begin to notice effects sooner, adhering to the 6-week timeframe helps to minimize trial-and-error in treatment, ensuring that patients receive adequate time for potential therapeutic benefits before switching medications. It also helps providers avoid prematurely discontinuing a potentially effective treatment.