Dutasteride (Avodart)
Also known as: Avodart, Dutasterid, Dutasteride, Dut, Duta
Blocks both isoforms of 5-alpha-reductase and suppresses DHT further than finasteride — with a half-life of weeks, which changes what stopping means.
Substance family
Which one works depends entirely on the cause. 5-alpha-reductase inhibitors block a conversion; receptor blockers block the receptor; minoxidil acts on the growth cycle regardless of androgens.
Strain profile
Where this substance is most likely to hit — a rough orientation, individually dependent on dose, duration and predisposition.
This substance works against
Dosing & protocols by goal
Rough orientation ranges as reported in harm-reduction literature — not an individual treatment plan. Doses are individual and open-ended; frequency depends on the ester or half-life.
Prostate enlargement (approved indication)
MedicalDose
0.5 mg / day
Frequency
1× daily
Cycle length
Ongoing, medically supervised
Suppresses DHTDHTA far more potent androgen the body makes from testosterone — responsible for hair loss and prostate effects. by roughly 90%, compared with 65–70% for finasteride.
Androgenetic alopecia
AdvancedDose
0.5 mg / day
Frequency
1× daily, or 2–3× weekly
Cycle length
Ongoing
The long half-lifehalf-lifeHow long it takes for half the substance to leave the body — it determines dosing frequency, not duration of effect. means less frequent dosing still maintains suppressionsuppressionThe body shutting down its own testosterone production because an external source is present. — which is why some use it every other day or a few times a week.
Cautious entry
AdvancedDose
0.5 mg, 2× / week
Frequency
2× weekly
Cycle length
Ongoing
Used to test tolerance before committing. Because of the 5-week half-lifehalf-lifeHow long it takes for half the substance to leave the body — it determines dosing frequency, not duration of effect., levels still accumulate over the first months.
Side effect & countermeasure
Typical problems and what you can do to reduce harm — at a glance. Does not replace medical monitoring.
Problem
Five-week half-life makes stopping slow
Countermeasure
This is the practical difference from finasteride. If side effects appear, discontinuation does not resolve them quickly — the substance takes months to clear. Anyone uncertain about tolerance should start with finasteride, where a decision to stop takes effect within days.
Problem
No effect against DHT-derived compounds
Countermeasure
Like finasteride, dutasteride acts on the conversion step. Drostanolone, stanozolol, oxandrolone and methenolone are already DHTDHTA far more potent androgen the body makes from testosterone — responsible for hair loss and prostate effects. derivatives — stronger suppressionsuppressionThe body shutting down its own testosterone production because an external source is present. of an enzyme that is not involved changes nothing. Minoxidil or a topical receptor blocker such as RU58841 are the mechanisms that apply there.
Problem
Higher rate of sexual side effects than finasteride
Countermeasure
Blocking both isoforms suppresses DHTDHTA far more potent androgen the body makes from testosterone — responsible for hair loss and prostate effects. further, and the side-effect profile follows. If they appear, the long half-lifehalf-lifeHow long it takes for half the substance to leave the body — it determines dosing frequency, not duration of effect. means waiting them out is slow — factor that into the decision to start.
Problem
Mood changes and depressive symptoms
Countermeasure
Both isoforms are involved in neurosteroid production, so the mechanism behind mood effects applies more strongly here than with finasteride. Pre-existing depression is a reason to discuss alternatives.
Problem
Distorted PSA readings
Countermeasure
Dutasteride roughly halves PSAPSAA prostate marker that androgens can raise — worth a baseline before it is needed., as finasteride does. Tell any doctor measuring it, otherwise prostate screening is unreliable.
Problem
Blood donation restriction
Countermeasure
Because of the long half-lifehalf-lifeHow long it takes for half the substance to leave the body — it determines dosing frequency, not duration of effect. and teratogenic potential, blood donation is restricted for a period after stopping — relevant for anyone donating to manage hematocrithematocritThe percentage of blood made up of red cells — rises on androgens and thickens the blood..
Overview
Dutasteride blocks both isoforms of 5-alpha-reductase, where finasteride blocks only type 2. The result is DHT suppression of roughly ninety percent instead of two thirds, and correspondingly stronger effects on hair — in head-to-head trials it outperforms finasteride.
It is approved for hair loss only in South Korea and Japan; elsewhere the indication is prostate enlargement and hair use is off-label.
Two properties distinguish it from finasteride in ways that matter more than the extra suppression.
Mechanism of Action
Type 2 of the enzyme dominates in prostate and hair follicles; type 1 is more prominent in skin and sebaceous glands and contributes a meaningful share of circulating DHT. Blocking both is why dutasteride reaches ninety percent suppression.
The half-life is the second difference and the more consequential one. Finasteride clears within a day or so; dutasteride has a half-life of around five weeks. Levels build over months and take months to fall.
That cuts both ways. It makes dosing forgiving — missing a day, or dosing a few times a week rather than daily, still maintains suppression. It also means that if something goes wrong, stopping is not a quick exit. Side effects that would resolve within days off finasteride can persist for weeks or months here.
For anyone unsure how they tolerate 5-alpha-reductase inhibition, that argues for starting with finasteride and switching later rather than the other way round.
The limitation it shares with finasteride is complete: neither does anything about DHT-derived compounds. Drostanolone, stanozolol, oxandrolone and methenolone bypass the enzyme entirely. Suppressing that enzyme more thoroughly does not change an equation the enzyme is not part of.
Typical Context
Half a milligram daily, or two to three times weekly given the long half-life. Some use it after finasteride proves insufficient; others start with it for the stronger effect.
The tolerance question deserves more weight than it usually gets. The side-effect profile is the same as finasteride's but somewhat more frequent, and the exit is considerably slower. Testing tolerance with the shorter-acting drug first is the more reversible order of operations.
Side Effects & Risks
- Reduced libido, erectile dysfunction, reduced ejaculate volume — somewhat more frequent than with finasteride
- Mood changes, depressive symptoms
- Gynecomastia, rarely
- PSA readings roughly halved
- Very slow clearance if problems occur
- Blood donation restricted for a period after stopping
- No effect on hair loss driven by DHT-derived compounds
Blood Work & Monitoring
- PSA — halved; the treating doctor needs to know
- Estradiol (sensitive) — can rise modestly
- Total/free testosterone
- DHT — if confirmation of the effect is wanted
Harm-Reduction Notes
- Test tolerance with finasteride first — stopping that takes days rather than months
- Useless against drostanolone, stanozolol, oxandrolone and methenolone, exactly as finasteride is
- The long half-life allows less frequent dosing without losing suppression
- Tell any doctor measuring PSA
- Note the blood donation restriction if donation is part of managing hematocrit
- A history of depression belongs in the decision
Legal status by region
Regulation differs considerably between jurisdictions and changes over time. This is a rough orientation, not legal advice — check the rules that apply where you are.
| Region | Regulatory status |
|---|---|
| United States | Prescription-only medicineApproved for prostate enlargement; use for hair loss is off-label. |
| EU / UK | Prescription-only medicineApproved for prostate enlargement. |
| South Korea / Japan | Approved for androgenetic alopeciaThe two markets where the hair-loss indication is licensed. |
| Parts of Asia, Latin America & Middle East | Pharmacy availability varies |
| Competitive sport | Not prohibited |