DHT blockers are the most evidence-backed treatment for preventing male pattern baldness. Dihydrotestosterone (DHT) is the hormone directly responsible for miniaturizing hair follicles in androgenetic alopecia, and blocking its production slows or halts hair loss in 80 to 90% of men.
This guide covers every DHT blocker available in 2026, from prescription medications to topical formulations to natural alternatives, with data on how well each one works.
How DHT Causes Hair Loss
Testosterone circulates through the bloodstream and is converted to DHT by the enzyme 5-alpha reductase (5AR). There are two types of this enzyme:
- Type I 5AR: Found primarily in the skin and liver
- Type II 5AR: Found primarily in the prostate and hair follicles
DHT is 2 to 3 times more potent than testosterone at binding to androgen receptors. When DHT attaches to receptors in genetically susceptible scalp follicles, it shortens the anagen (growth) phase of the hair cycle. Over successive cycles, each hair grows thinner and shorter. This process is called miniaturization.
The Miniaturization Cycle
| Cycle Stage | Normal Hair | DHT-Affected Hair |
|---|---|---|
| Anagen (growth) | 2-6 years | Progressively shorter each cycle |
| Catagen (transition) | 2-3 weeks | Normal |
| Telogen (rest) | 2-3 months | Progressively longer |
| Hair diameter | 60-100 microns | Decreases 10-20% per cycle |
| Final stage | N/A | Vellus hair (invisible peach fuzz) |
The follicle does not die immediately. It transitions from producing thick terminal hair to thin vellus hair over many cycles. This is why early intervention with DHT blockers can reverse some thinning: the follicle is still alive but producing progressively weaker hair.
Prescription DHT Blockers
Finasteride (Propecia)
Finasteride 1mg daily is the most widely prescribed DHT blocker for hair loss. It selectively blocks type II 5-alpha reductase, reducing serum DHT by approximately 70%.
| Metric | Data |
|---|---|
| FDA-approved for hair loss | Yes (1997) |
| DHT reduction | ~70% |
| Halts further loss | 83-90% of men |
| Produces visible regrowth | 66% of men at 2 years |
| Time to results | 6-12 months |
| Monthly cost (generic) | $10-$30 |
| Must continue indefinitely | Yes |
Side effects: Sexual side effects (reduced libido, erectile dysfunction, decreased ejaculate volume) occur in approximately 2 to 4% of men in clinical trials. These typically resolve after discontinuation. Reports of persistent side effects exist but are not confirmed by large-scale controlled studies.
Dutasteride (Avodart)
Dutasteride 0.5mg blocks both type I and type II 5-alpha reductase, reducing serum DHT by over 90%. It is FDA-approved for benign prostatic hyperplasia (BPH) and prescribed off-label for hair loss.
| Metric | Data |
|---|---|
| FDA-approved for hair loss | No (off-label use) |
| DHT reduction | >90% |
| Halts further loss | 85-95% of men |
| Produces visible regrowth | Higher than finasteride in head-to-head studies |
| Time to results | 6-12 months |
| Monthly cost (generic) | $30-$60 |
| Half-life | 5 weeks (vs. 6-8 hours for finasteride) |
Dutasteride's longer half-life means it stays in the body much longer than finasteride. This provides more consistent DHT suppression but also means side effects take longer to resolve if they occur.
Finasteride vs Dutasteride Comparison
| Factor | Finasteride 1mg | Dutasteride 0.5mg |
|---|---|---|
| DHT reduction | ~70% | >90% |
| Hair count increase (1 year) | +86 hairs/cm2 | +109 hairs/cm2 |
| FDA-approved for hair loss | Yes | No (off-label) |
| Side effect rate | 2-4% | 3-5% |
| Long-term safety data | 20+ years | Less extensive for hair use |
| Time to clear system | 1-2 weeks | 4-6 months |
| Cost (generic) | $10-$30/month | $30-$60/month |
Most dermatologists start with finasteride and switch to dutasteride only if finasteride does not produce adequate results after 12 months.
Topical DHT Blockers
Topical Finasteride
Topical finasteride (0.1% to 0.25% solution) is applied directly to the scalp. The goal is to achieve local DHT reduction in the scalp while minimizing systemic absorption and the associated side effect risk.
| Metric | Topical Finasteride |
|---|---|
| DHT reduction (scalp) | 30-50% locally |
| DHT reduction (serum) | 15-30% (lower than oral) |
| Sexual side effect rate | Lower than oral (studies ongoing) |
| Application | Once daily to scalp |
| Monthly cost | $40-$80 |
| Availability | Compounding pharmacies, some online clinics |
Topical finasteride is a reasonable option for men who experienced side effects on oral finasteride or who want to minimize systemic exposure. Evidence is growing but less extensive than for the oral form.
Ketoconazole Shampoo
Ketoconazole 2% shampoo (Nizoral) has mild anti-androgenic activity when applied topically. It is not a standalone treatment but is commonly used as an adjunct to oral DHT blockers.
Used 2 to 3 times per week, ketoconazole shampoo reduces scalp DHT and inflammation. It is available over the counter at 1% strength and by prescription at 2%.
Natural DHT Blockers
Natural supplements marketed as DHT blockers have significantly weaker evidence than prescription options. None have been shown to match finasteride or dutasteride in controlled clinical trials.
| Natural Compound | Proposed Mechanism | Evidence Level | DHT Reduction |
|---|---|---|---|
| Saw palmetto | 5AR inhibition | Low to moderate | 10-30% (estimated) |
| Pumpkin seed oil | 5AR inhibition | Low | Not well quantified |
| Green tea extract (EGCG) | 5AR inhibition | Low | Minimal in humans |
| Pygeum bark | Anti-androgenic | Low | Not well quantified |
| Stinging nettle root | 5AR inhibition | Very low | Not well quantified |
Saw Palmetto
Saw palmetto is the most studied natural DHT blocker. A small number of studies suggest it may produce mild improvement in hair density, but the effect size is substantially smaller than finasteride. One 2012 study found that saw palmetto 320mg daily improved hair density in 38% of participants versus 68% for finasteride 1mg.
Saw palmetto may be an option for men who cannot or will not use prescription medication, but expectations should be calibrated accordingly.
Choosing the Right DHT Blocker
Decision Framework
| Situation | Recommended DHT Blocker |
|---|---|
| First-time treatment, any Norwood stage | Finasteride 1mg oral |
| Finasteride tried, insufficient results at 12 months | Dutasteride 0.5mg oral |
| Side effects on oral finasteride | Topical finasteride 0.25% |
| Cannot tolerate any prescription | Saw palmetto 320mg + ketoconazole shampoo |
| Post-hair transplant maintenance | Finasteride 1mg oral (or dutasteride) |
| Prostate health concerns at 50+ | Discuss finasteride/dutasteride dual benefit with doctor |
Combination Therapy
DHT blockers work best when combined with a growth stimulant. The standard combination is:
- Finasteride 1mg daily (blocks DHT, prevents further loss)
- Minoxidil 5% topical or 2.5mg oral (stimulates growth independently of DHT)
- Ketoconazole 2% shampoo 2-3 times per week (reduces scalp DHT and inflammation)
This three-pronged approach targets hair loss through multiple mechanisms and produces better results than any single treatment alone.
Get Your Assessment
Upload a photo at myhairline.ai/analyze for a free AI assessment of your current hair loss stage. Understanding your Norwood classification helps determine the right DHT blocker strategy for your situation.