“Brain Fog”: A Cognitive Symptom of Post-finasteride Syndrome

If you've read about Post-finasteride Syndrome (PFS), you're likely familiar with the persistent sexual side effects reported by some individuals who have taken the drug finasteride. However, beyond the well-documented sexual symptoms, finasteride can significantly affect cognitive abilities indefinitely, leading to challenges that impact daily life and well-being. In this article we review what brain fog is, how it presents in PFS, and the resources and support available for patients experiencing this symptom. 

What is finasteride “brain fog”/cognitive impairment?

PFS patients report a range of cognitive impairment symptoms that significantly impair their quality of life. They can range in severity from being annoyances to causes of disability and/or suicide. These symptoms often include, but are not limited to:

  • Reduced mental clarity: The pervasive sense of "brain fog," described as feeling mentally sluggish, cloudy, or unable to think clearly. 

  • Difficulty concentrating: A diminished ability to focus on tasks.

  • Executive dysfunction: Challenges with planning, organizing, and executing tasks, further complicating personal and professional responsibilities and aims. 

  • Difficulty processing information: Difficulty in taking in, interpreting, and responding to information. 

  • Impaired visual-spatial processing: Difficulty orienting yourself and other objects in space. 

  • General cognitive impairment: A general reduction in cognitive capacity.

How PFS patients describe “brain fog”

Here are some descriptions from patients based on documented interviews and stories: 

“Nothing flows freely from my mind anymore. I used to be able to type lengthy, eloquent emails at work or to friends with ease [...], now it’s a real chore to type much. I find myself with fewer things to say and tend to drift out of conversations quite easily, not having said much. [...] I can just zone out into a world of my own and not communicate much, sort of zombied out.“

“Severe brain fog that feels like a mix between being drunk, drugged and having the flu. It also resembles the way your brain feels when you wake up in the middle of the night and you are extremely groggy. Frequently I feel so bad I can’t even watch a movie or read for more than 5 minutes at a time. All I can do then is sit or lay down with my eyes closed.“

It should be noted that “brain fog” has been reported as a side effect experienced while taking finasteride. Self-reports indicate that it can take up to 3 months for on-drug side effects to resolve after discontinuation of the drug. After that, the symptoms can be considered persistent. 

How common is cognitive impairment as a symptom of Post-finasteride Syndrome?

While there are estimations of incidence for cognitive impairment as a side effect of finasteride, there is limited data with which to estimate the prevalence of cognitive impairment in PFS.

Research findings on cognitive impairment in PFS 

Two separate studies have found an overexpressed androgen receptor in affected tissue from PFS patients (Di Loreto et al. 2014; Howell et al. 2021), and in addition one of them examined for and found concurrent differential expression of several thousand genes (Howell et al. 2021). Notably, there are numerous pathways in several parts of the brain by which adequate androgen receptor function is necessary for cognitive function. 

Other studies of PFS have found altered neurosteroid levels (Melcangi et al. 2013; Melcangi et al. 2017) present in the cerebrospinal fluid of some patients.   

It is essential to note that more research into post-finasteride syndrome is desperately needed. PFS is currently without an accurate animal model, pathomechanistic understanding, and as a result, safe and effective treatment. 

Does persistent cognitive impairment or brain fog after finasteride go away? Is it reversible?

Some patients have reported improvement in cognitive symptoms over time. However, PFS is understood to persist indefinitely, and it is currently without safe and effective treatment. 

Managing and coping with cognitive impairment

For those who may be struggling with symptoms, here are some general recommendations:

  1. Focus on self-care: Try to find routines and activities that help you personally.

  2. Be practical about your life situation and/or relationships: Try not to think too far ahead and catastrophize. PFS affects individuals to different degrees and some experience improvements over time. 

  3. Familiarize yourself with the scientific literature: Read through previous research into PFS on our website in order to better understand your condition.

  4. Support research: Further research into PFS, based on a theory and/or conceptualization of the condition that is backed by all previous research findings and can plausibly explain all symptoms reported by patients, is the only way toward a treatment.

What about supplements or other drugs to help treat symptoms?

There are currently no evidence-based items recommended for treatment of cognitive impairment stemming from PFS. In general, patients have reported worsening by attempting to treat their symptoms with anti-androgenic substances. We are obligated to make patients aware as this has preceded patient suicide.  

Next steps 

If you or a family member is experiencing cognitive impairment from finasteride, there are multiple resources available to you and ways you can help:

Learn more about Post-Finasteride Syndrome 

  • Read our Frequently Asked Questions page.

  • Inform your physician. PFS Network provides resources to help patients discuss PFS symptoms with their clinicians. Not sure about how to start the conversation? Start here.

  • Read about previous studies of PFS. 

  • Experiencing other symptoms? You can find information on other persistent side effects from finasteride here.

Help us fund research 

  • Consider donating to help fund our research projects. The best and easiest way to support research into PFS is through a monthly recurring donation. Every amount matters. 

  • Learn more about our ongoing research projects.

Report your symptoms

  • Refer to your country’s pharmacovigilance organization by reviewing our regulatory list, or by consulting the World Health Organization’s (WHO) list of reporting resources here: https://who-umc.org/ (Scroll to the bottom to select your country from the map provided).

Stay up-to-date

  • Sign up for our mailing list to stay up to date on research and news related to PFS: Email sign-up

  • View and subscribe to our YouTube channel. You may also consider appearing on our patient interview series. 

Connect with other PFS patients

  • Follow our Patient Stories & Interviews to hear how others have experienced similar symptoms of cognitive impairment.

  • Join our community forums. PFS Network operates the largest and longest-running standalone patient forum, propeciahelp.com, where patients can connect with others affected by adverse reactions to finasteride. The charity also operates r/FinasterideSyndrome on Reddit.