Finasteride Does Not Directly Cause Dizziness
Finasteride itself does not cause dizziness—this side effect is specifically associated with alpha-blocker medications, not 5-alpha-reductase inhibitors like finasteride. 1
The Evidence Against Finasteride Causing Dizziness
The most authoritative guideline data directly addresses this misconception:
In head-to-head trials comparing finasteride (a 5-alpha-reductase inhibitor) to alpha-blockers for benign prostatic hyperplasia, dizziness and postural hypotension were statistically more frequent among patients receiving alpha-blocker therapy, not finasteride. 1
The established adverse event profile of finasteride is limited to sexual dysfunction (erectile dysfunction, decreased libido, reduced ejaculate volume), gynecomastia, and breast tenderness—dizziness is notably absent from this list. 2, 3
Why This Confusion Occurs
This is a common clinical pitfall that arises from:
Medication class confusion: Alpha-blockers (like tamsulosin, doxazosin) are frequently prescribed alongside or instead of finasteride for BPH, and these medications cause dizziness through vasodilation and orthostatic hypotension. 1
Polypharmacy in the typical patient population: Men taking finasteride for BPH are often older with multiple medications that could cause dizziness.
The Actual Mechanism of Finasteride
Finasteride works by inhibiting 5-alpha-reductase (primarily Type 2), which converts testosterone to dihydrotestosterone (DHT). 3, 4 This mechanism:
- Reduces DHT levels by approximately 70% in serum and 85-90% in the prostate 4
- Decreases circulating neuroactive steroids including allopregnanolone and other GABA-modulating compounds 5, 6
- Has no direct cardiovascular or vestibular effects that would produce dizziness 1
Neuropsychiatric Effects vs. Dizziness
While finasteride does affect neuroactive steroid formation, the clinical manifestations are depression-related symptoms, not dizziness:
- The reduction in GABAergic neuroactive steroids (allopregnanolone, pregnenolone) may contribute to depressive symptoms in isolated cases 5, 6
- These neurosteroid changes affect mood and anxiety pathways, not vestibular or cardiovascular systems that cause dizziness 5
Clinical Bottom Line
If a patient on finasteride reports dizziness, look elsewhere for the cause—review their alpha-blocker use, antihypertensives, or other medications with known cardiovascular effects. 1 The discontinuation rate for finasteride due to adverse events (6-7%) matches placebo, and dizziness is not among the documented reasons. 2, 3