The Complete Finasteride FAQ: 25 Questions Answered With Evidence

Yes. In the Merck Phase III trials, 87% of men showed improvement or maintained their hair at 2 years. The 10-year Japanese study showed 99.1% of men demonstrated improvement or prevention of progression over a full decade. Finasteride is one of the most well-studied hair loss treatments available. Read: How Finasteride Works

DHT drops within 1–2 weeks of starting. Visible changes require 3–12 months due to the hair growth cycle. Most dermatologists recommend evaluating results at 12 months minimum. Men who quit at month 3 often miss the improvement that comes later. Read: Finasteride Results Month by Month

1mg daily is the FDA-approved hair loss dose. It reduces DHT by approximately 65%. Some dermatologists prescribe 0.5mg daily or 1mg every other day, which still provides meaningful DHT reduction (~55% at 0.5mg). The 5mg dose (for BPH) only adds ~5% more DHT reduction — not worth the additional exposure for hair loss. Read: Finasteride Dosage Guide

Generic finasteride 1mg: $3–7/month with GoodRx coupons. The 5mg tablet splitting hack: $1.50–3/month. Telehealth all-inclusive: $16–25/month. Mark Cuban's Cost Plus Drugs: ~$5.82/month. It's one of the cheapest prescription medications in existence. Read: Finasteride Cost Guide

Propecia is the brand name for finasteride 1mg. The generic version is identical in every clinically meaningful way — same active ingredient, same bioavailability, same efficacy — at a fraction of the price.

In clinical trials, 1.3% of men on finasteride reported ED compared to 0.7% on placebo — an absolute difference of 0.6%. Most cases resolved with continued use or upon discontinuation. The nocebo effect may amplify reported rates significantly. Read: Finasteride and ED

Yes. No drug interactions exist between finasteride and PDE5 inhibitors (sildenafil/Viagra, tadalafil/Cialis). They work through completely different mechanisms. Many men take both concurrently. Read: Can You Take ED Medication With Finasteride?

Merck Phase III: 3.8% sexual AE on finasteride vs 2.1% on placebo. Absolute risk increase: 1.7%. Side effects decreased to ≤0.3% by year 5. The 10-year study: 6.8% total adverse reactions, all mild, zero serious. Read: Side Effects by the Numbers

This is debated. The FDA has added warnings about persistent sexual side effects and suicidality. Biological plausibility exists (neurosteroid disruption). But PFS hasn't been validated as a distinct syndrome by any regulatory body, and the nocebo effect is a significant confounding factor. Our position: side effects are real for some men; the persistence question remains unresolved. Read: PFS Evidence Review

Finasteride slightly increases testosterone — by about 10–20% — because it blocks the conversion to DHT. This increase stays well within the normal physiologic range and has no meaningful clinical effect. Finasteride does NOT lower testosterone.

Yes, this is common practice. A 5mg tablet split into quarters gives approximately 1.25mg per piece — close enough to the 1mg dose to be clinically equivalent. Use a pill splitter for consistent results. Cost: as low as $1.50–3/month.

No. Morning, evening, or afternoon — the timing doesn't affect efficacy. Consistency matters more than timing. Pick a time that's easy to remember and stick with it.

One missed dose is meaningless. Finasteride's effect on DHT lasts well beyond a single day — the enzyme-drug complex has a turnover half-life of approximately 30 days. Missing a day occasionally won't affect your results. Missing weeks or months will.

DHT returns to normal within 14 days. Hair loss resumes. Within 12 months, gains are typically lost. This isn't because finasteride is addictive — it's because the underlying condition resumes when you stop treating it. Read: What Happens When You Stop

It's a trade-off. Topical achieves over 100-fold lower plasma levels (fewer systemic side effects possible) but less DHT reduction (~34.5% vs ~65% oral). For men concerned about systemic side effects, topical is a reasonable option. For maximum efficacy, oral remains the standard. Read: Topical vs Oral

Different tools for different jobs. Finasteride blocks the cause (DHT). Minoxidil stimulates growth. The 2025 meta-analysis ranked using both together as the most effective approach. If you can only choose one, finasteride addresses the root cause more directly. Read: Why Use Both

Dutasteride is stronger. It reduces DHT by 92–98% vs finasteride's ~70% and inhibits all 3 isoenzymes of 5-alpha reductase vs finasteride's 2. Meta-analysis shows +28.57 more hairs with dutasteride. But dutasteride has a 4–5 week half-life vs finasteride's 6–8 hours, making side effects harder to reverse. Most guidelines recommend trying finasteride first. Read: Finasteride vs Dutasteride

Not FDA-approved for women. Category X for pregnancy (can cause genital malformations in male fetuses). Some dermatologists prescribe it off-label for postmenopausal women. Spironolactone is the preferred antiandrogen for women. Read: Finasteride for Women

It can reduce sperm count and motility in some men. This is reversible within 3 months of discontinuation. If you're planning to conceive, discuss timing with your provider. Many dermatologists recommend pausing finasteride 3 months before attempting conception.

No clinical evidence that finasteride 1mg impairs muscle gains, strength, or athletic performance. It slightly increases testosterone (stays in normal range). DHT contributes to muscle development, but the effect at hair-loss doses is negligible. Read: Finasteride and the Gym

Yes. The 10-year safety data includes older men. Additional consideration: finasteride reduces PSA by ~50%, so any doctor ordering a PSA test must know you're taking it. There may also be secondary prostate health benefits. Read: Finasteride and Prostate Health

Yes. No known drug interactions. Completely different metabolic pathways. Many men take both concurrently. Read: Finasteride + GLP-1 Drug Interactions

If you've been on finasteride for 12+ months with inadequate response, dutasteride is a reasonable next step. It achieves greater DHT reduction. You can switch directly with no taper needed. Discuss with your provider. Read: Switching Guide

Likely yes. The temporary shedding at weeks 2–8 (the "dread shed") occurs because finasteride pushes resting follicles into a new growth cycle. The old telogen hairs fall out to make way for new anagen hairs. It's counterintuitive but typically a positive indicator.

Finasteride tends to be most effective at the crown and midscalp. Hairline improvement is possible but less consistent — the temples are the most DHT-sensitive area and often the hardest to recover. Starting early (before significant recession) gives the best hairline results. Adding minoxidil can improve outcomes at the hairline specifically.