Pablo had been losing his hair since his late twenties. Like millions of men, he started a common prescription medication called finasteride, which became so routine in his daily life that he almost forgot he was taking it. It was working well, and he built his career and started a family.
By the time I met Pablo, he was in his early forties. Referred by a family member I’d supported through a complicated health journey, he came to me because he was struggling with severe anxiety, irritability, and difficulty connecting with the people closest to him. His relationships at home and at work were strained, and he didn’t recognize himself in his edginess. He also had persistent digestive issues that weren’t responding to the usual interventions.
Pablo was seeing a primary care physician, a psychotherapist, and the staff at his hair loss clinic. Each practitioner worked from one of three separate lanes, and none of them was talking to the others.
The slow work of connecting dots
When I reviewed Pablo’s full history, including medications, supplements, health conditions, timelines, and how different areas of his health had shifted over the years, I started to see a pattern. His anxiety predated the finasteride, but had gotten significantly worse during the decade he’d been on it. Research over the past several years has increasingly linked finasteride to depression, anxiety, and other psychiatric effects, particularly in younger men (1, 5, 6). A large pharmacovigilance study using the WHO’s global safety database found a significant signal for depression and anxiety in finasteride users under 45 (1). Population-based studies have found that the risk of depression nearly doubles in the first 18 months of use and remains modestly elevated thereafter (2).
The biological mechanism is plausible: finasteride inhibits the enzyme that produces allopregnanolone, a neurosteroid with antidepressant and anti-anxiety properties (5, 7). Reduce allopregnanolone, and you may shift the brain’s emotional control panel.
But the story gets more interesting and more complicated.
The gut connection
Pablo also had gastrointestinal symptoms, and he was eventually diagnosed with an H. pylori infection. Was finasteride contributing to his gut issues too? Honestly, I can’t say with confidence, and that honesty is important. H. pylori alone could explain his digestive symptoms. But preclinical research has shown that finasteride alters gut microbiota composition and induces intestinal inflammation in animal models, with changes persisting even after the drug is stopped (4, 7). A pilot study in men with persistent symptoms after finasteride use found reduced gut microbial diversity compared to healthy controls (3).
The gut and the brain are in constant conversation, what researchers call the gut-brain axis. When one is disrupted, the other often follows (7). In Pablo’s case, I was looking at a client with both gut and brain symptoms, on a medication that research suggests can affect both systems, who also had an independent gut infection that could be driving gut symptoms on its own.
If I had assumed finasteride was the sole culprit for his GI issues, we might have missed the H. pylori entirely. Nothing causes everything, and attention to nuance is important in clinical practice.
What changed
When I shared my findings and the supporting research with Pablo, he was surprised. He’d never considered that his hair loss medication could be connected to his anxiety or his gut. But when he thought back over the timeline, he noted that his symptoms had worsened after starting finasteride and improved significantly after, in consultation with his medical team, he stopped taking it.
I asked Pablo to share my notes and the relevant research with his other practitioners, and I left the door open for them to contact me if they wanted to discuss the case. I always advise clients not to change or discontinue medications without consulting their prescribing physician.
We also worked on rebuilding his gut health through probiotic supplementation and expanding the range and color of plant foods in his diet. This is a practical, evidence-informed approach to supporting microbial diversity.
The real problem isn’t the drug
This piece is not an argument against finasteride. Finasteride helps many people, and the fact that a medication can cause side effects in some individuals doesn’t mean it will in all (5). I’ve seen clients assume based on some alarmist online content that it must be the root of all their problems. The kind of thinking that attributes everything to one cause can lead to missed opportunities at every step of the health journey. A drug with potential side effects might still be the right choice for a given person.
The real problem in Pablo’s case wasn’t finasteride itself. It was the compartmentalization of his health care. He had multiple practitioners, each excellent in their own domain, none of whom had the full picture. His hair loss doctor wasn’t asking about his mental health and relationships. His therapist wasn’t asking about his medications. His PCP wasn’t asking about his gut in the context of his mental health. And none of them had the time to sit down with his complete history and look for patterns across systems.
This isn’t a criticism of any individual practitioner. It’s a structural reality of how healthcare is organized. Specialists specialize. That’s their value. But when health gets complicated, someone needs to step in and map out the whole picture.
The takeaway
The patterns I noticed in Pablo’s case aren’t rare, and they aren’t even limited to finasteride. I regularly see clients of all ages and genders whose gut and brain symptoms are entangled in ways that no single specialist is ideally positioned to untangle. The connections emerge from the unglamorous, slow work of reviewing timelines, cross-referencing medications with symptoms, and staying current with the research.
Make sure you have at least one person on your healthcare team who is connecting the dots for you. And make sure they have your full medication list, your supplement list, and your full health history, even (especially) the things that seem unrelated to why you’re there.
Sometimes, a piece that doesn’t seem to fit or matter is the one that makes the whole picture make sense.
And yes, I work with 1:1 clients and I specialize in complex health issues!
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References
(1) Nguyen DD, Marchese M, Cone EB, et al. Investigation of suicidality and psychological adverse events in patients treated with finasteride. JAMA Dermatology. 2021;157(1):35-42.
(2) Welk B, McArthur E, Ordon M, et al. Association of suicidality and depression with 5α-reductase inhibitors. JAMA Internal Medicine. 2017;177(5):683-691.
(3) Borgo F, Macandog AD, Diviccaro S, et al. Alterations of gut microbiota composition in post-finasteride patients: a pilot study. Journal of Endocrinological Investigation. 2021;44(6):1263-1273.
(4) Diviccaro S, Giatti S, Borgo F, et al. Treatment of male rats with finasteride induces long-lasting effects on depressive-like behavior, hippocampal neurogenesis, neuroinflammation and gut microbiota composition. Psychoneuroendocrinology. 2019;99:206-215.
(5) Traish AM. Post-finasteride syndrome: a surmountable challenge for clinicians. Fertility and Sterility. 2020;113(1):21-50.
(6) Brezis M. Failing public health again? Analytical review of depression and suicidality from finasteride. Journal of Clinical Psychiatry. 2025;86(4).
(7) Diviccaro S, Oleari R, Amoruso F, et al. Exploration of the possible relationships between gut and hypothalamic inflammation and allopregnanolone: preclinical findings in a post-finasteride rat model. Biomolecules. 2025;15(7).