Persistent side effects from the 5alpha reductase inhibitor finasteride, dutasteride and saw palmetto extract (Propecia, Proscar, Avodart, generics)

The Post-Finasteride Syndrome (PFS) is a devastating condition characterized by the persistence and development of diverse sexual, neurological and physical side effects after discontinuation of 5-alpha reductase inhibitors such as finasteride and Dutasteride. Symptoms are variably distributed from person to person, and vary widely in severity. The condition has a life-altering impact on victims and their loved ones, too often leading to career loss, the loss of relationships, and suicide. The pathomechanism(s) are currently unclear, and the predisposition that cause a subset of young people to develop PFS from as little as a single exposure to a 5-alpha reductase inhibitor remain unknown.

In terms of adverse drug reactions, PFS has a traditionally counter-intuitive clinical presentation given the condition’s persistence and even worsening after the causal medication has left the patient’s system. This atypical presentation of side effects and the broad spectrum of treatment-resistant and often permanent health problems caused by exposure to finasteride have resulted in sufferers facing great difficulty in achieving the necessary acknowledgement of medical professionals.

Postt-Finasteride Syndrome can develop after as little as one dose or suddenly after years of taking the drug without prior complaint, with many severe cases having taken the medication for only days. While not a universal experience, a commonly observed pattern is as follows:

  • The patient ceases taking a 5ARI and may experience a brief resolution of side effects
  • Unfortunately this resolution is short lived, and in the next days/weeks, the patient experiences a “crash”
  • At this stage a varied range of symptoms can develop, including the rapid onset of anxiety and cognitive problems, loss of libido and sexual function and sleep disturbances.
  • Deterioration of androgen-dependent tissue, including penile tissue loss and muscle wasting, can become apparent over the next weeks or months
  • Patients symptoms can remain indefinitely, with variable improvement or deterioration over time

PFS is without a consistent biomarker, however patients with prior hormonal bloodwork will often report significant alterations to their serum hormonal profile following onset of the condition including raised or reduced testosterone. Low luteinising hormone values is commonly reported. Additionally, low vitamin D and signs of metabolic alteration including increased triglycerides and elevated bilirubin can be frequently apparent. Basic urological evaluation may be subclinical or unrevealing, but this is not always the case and clinical evaluation of PFS patients describing a severe or total sexual dysfunction and penile changes often receive relevant diagnoses including penile venous leak, microcalcifications, fibrosis and markers of neuropathy. These outcomes, as with all effects, are not dose dependent, often developing rapidly after cessation in persistently and severely affected patients with extremely brief exposure to finasteride.

Therapeutic attempts meet with very low success and PFS is currently without safe and effective treatment. Patients can develop further symptoms in multiple domains of the condition upon rechallenge or exposure to antiandrogenic substances. The health of the most severely affected patients is so profoundly impacted that they cannot continue their lives in any meaningful capacity.

Post-Finasteride Syndrome Symptoms





  • Loss of libido and sexual desire


  • Erectile dysfunction; impotence
  • Loss of morning, nocturnal and spontaneous erections


  • Penile structural atrophy (length, girth)
  • Pudendal neuropathy, penile venous leak, microcalcifications, fibrosis
  • Perineal tissue loss
  • Peyronie’s disease and/or rotation
  • Skin and tissue changes; wrinkling, thinning, darkened
  • Numbness or lowered sensitivity
  • Testicular atrophy
  • Prostate problems
  • Decreased pubic hair


  • Sexual anhedonia
  • Premature ejaculation
  • Significantly increased refractory period
  • Decreased ejaculate volume and force
  •  Changes to seminal quality e.g. clear watery ejaculate
Androgenicity, muscle and body composition

  • Decreased oil/sebum production; Dry skin
  • Worsening skin quality, thinned skin and pigmentation changes
  • Muscle atrophy
  • Body-wide muscle twitches (fasciculations)
  • Fat distribution changes: increased android and gynoid fat
  • Gynecomastia
  • Facial changes: Sunken eyes, subcutaneous fat loss
  • Prominent veins
  • Changed body odour
  • Significantly increased or decreased rate of hair loss


  • Penile, testicular, and prostate pain
  • Myalgias
  • Joint and bone pain
  • Teeth pain
  • Headache, sensation of pressure in the head


  • Chronic fatigue
  • Loss of stamina, frequent exhaustion


  • Decreased body temperature
  • Significant weight gain or loss
  • Glucose intolerance, metabolic dysfunction


  • Discomfort, dysmotility
  • Constipation and/or diarrhoea
  • Pale stools

Bones and Teeth

  • Changes to bone structures, such as jaw line
  • Tooth decay, gum problems
  • Osteopenia, osteoporosis

Impaired organ function

Immune system problems

Dysautonomia including sinus arrhythmia, bradycardia, tachycardia



  • Severe short and long term memory/recall impairment


  • Decreased acuity, comprehension
  • Slowed thought processes, fogginess
  • Difficulty processing information and confusion
  • Impaired problem solving
  • Derealisation and depersonalisation
  • Loss of verbal fluency
  • Psychotic episodes

Emotion & Drive

  • Emotional blunting, flat affect
  • Anhedonia; Loss of interests, excitement, pleasurable or rewarding feelings
  • Loss of ambition, motivation
  • Loss of aggression; passivity
  • Loss of creativity


  • Clinical depression (eg. melancholic depression, suicidal ideation)
  • Treatment-resistant depression


  • Severe panic attacks
  • Generalized anxiety disorder, social anxiety disorder


  • Severe insomnia
  • Disrupted sleep/wake cycle
  • Loss of deep sleep
  • Sleep related movement disorders
  • Sleep apnea (obstructive and central)

Sensory changes

  • Vision impairment
  • Skin numbness
  • Tinnitus, hearing loss



Emerging evidence of the Post-Finasteride Syndrome

Elucidation of the biological mechanisms behind PFS is critical to the development of treatments for the many patients suffering. It is also essential for consumers to be adequately informed of the potentially catastrophic risks of 5-alpha reductase inhibitor products, as the syndrome remains unacknowledged by pharmaceutical industries and regulatory systems across the globe.

Funded primarily through donations to the PFS foundation, research has begun into the syndrome. Several notable findings have been made in studies of patients, including the persistent over-expression of the androgen receptor, significant alterations in the levels of neuroactive steroids (critical for brain and nervous system function), and neuropathy of the pudendal nerve. The emergent findings have led clinicians to speculate possible driving factors:

“A group of Italian researchers gave finasteride to rats and noticed that the number of androgen receptors in their brains went up. Moreover, the effects persisted long after the drug had been discontinued… [T]hey then called in men with PFS, took skin from the penis and found that the density of androgen receptors in men with PFS was about twice that of those without. Now, remember the idea of the testosterone bell curve and damping effects (little testosterone, little growth, more testosterone, more growth, even more testosterone, reduced growth)? I think this is what we are seeing here. With a greater concentration of receptors, the organ becomes more sensitive to testosterone and at a certain point, paradoxically, that sensitivity may shut down.”

— Charles J. Ryan, M.D., Professor of Clinical Medicine and Urology at the University of California, San Francisco, The Virility Paradox (2018).

The contribution of neurotransmission and heterogeneously altered neuroactive steroid levels and their receptors to the psychiatric symptomatology of the Post-Finasteride Syndrome has recently been considered:

“The important role of these 5α-reduced metabolites is suggested by the observation that their levels are modified in several experimental models of neurodegenerative and psychiatric disorders and their treatment exert important neuroprotective effects…The blockage of the enzyme 5α-R may have important negative consequences for nervous function…important side effects have been ascertained after treatment with inhibitors of this enzyme.

Interestingly, some of the examined neuroactive steroids are differently altered in plasma vs CSF and vs brain areas. In addition, these alterations are different depending on the specific brain areas. Furthermore, not only the levels of neuroactive steroids but also the expression of their receptors, like for instance AR and ERs or some subunits of the GABA-A receptors, are altered in these experimental conditions. For instance, an upregulation of AR occurred in rat cerebral cortex both after the chronic treatment then at the withdrawal. That is particularly interesting, because an upregulation of this steroid receptor also occurred in the prostate of patients treated with finasteride for BPH as well as in the prepuce of AGA patients showing persistent side effects. Other factors, in addition to neuroactive steroids, have been proposed to explain the pathogenesis of this syndrome as, for instance, alterations of dopaminergic signaling. Indeed, as demonstrated in animal models, finasteride treatment was able to impair the signaling of dopamine…involved in the regulation of sex drive”

— “Post-finasteride syndrome and post-SSRI sexual dysfunction: two sides of the same coin?” Giatti, S., Diviccaro, S., Panzica, G., Melcangi, R., Endocrine (2018).

Important research is ongoing into the Post-Finasteride Syndrome, and further investigation is urgently needed. If you or a loved one are suffering from PFS and wish to fund further research, please give what you can.