No studies have yet confirmed how long PFS symptoms can last. One research study found that side effects could persist for 40 months or more after stopping finasteride use, though this was just until the time of the interview. Symptoms may have persisted for longer. In these cases, the men surveyed had taken finasteride for an average of 28 months.
—Post-Finasteride Syndrome: Should You Be Worried? Wimpole Clinic Blog, September 15, 2023