Dutasteride

Dutasteride blocks both enzymes, not one

This section holds 6 lines from £18 to £90, averaging near £33 — among the cheapest sections stocked. The compounds here are dutasteride and one tamsulosin combination.

Everything interesting about it is the comparison with finasteride, and the difference is not one of degree in the way it is usually presented.

Type 1 and type 2

5-alpha reductase exists in two isoenzyme forms. Finasteride inhibits type 2. Dutasteride inhibits both type 1 and type 2, which is why it suppresses circulating DHT far more completely — the commonly cited figures put finasteride around 70% and dutasteride above 90%.

For androgenic hair loss, where DHT is the driver, more complete suppression is the argument for it. It is also the argument against it, depending on what you make of DHT having functions worth keeping.

The half-life is the practical difference

Dutasteride against finasteride

	Finasteride	Dutasteride
Enzymes blocked	Type 2	Type 1 and type 2
DHT suppression	~70%	>90%
Half-life	Hours	Weeks
Washout after stopping	Days	Months

That last row deserves more attention than it gets. Finasteride clears quickly, so someone who dislikes how it makes them feel can stop and know within a week or two. Dutasteride’s terminal half-life is measured in weeks, and it remains detectable in serum for months after the last dose.

Anyone worried about the sexual and mood side effects reported with 5-ARIs should understand that dutasteride removes the ability to change your mind quickly. That is a meaningful difference in risk, independent of whether the side effects are more likely.

What it is licensed for

Dutasteride is licensed in the UK for benign prostatic hyperplasia, not for hair loss. Finasteride carries a hair-loss licence at the lower dose; dutasteride’s use for that purpose is off-label here, though it is approved for it in some other countries.

The tamsulosin combination in this section is a BPH product specifically — tamsulosin relaxes smooth muscle in the prostate and bladder neck and does nothing for hair.

Where it fits alongside the rest of the catalogue

The same limitation applies as with finasteride: it blocks conversion of testosterone to DHT, so it helps where testosterone is the driver. It does nothing about compounds that are already DHT derivatives, and against 19-nor compounds it may make matters worse. That reasoning is set out in full on the finasteride page and applies here unchanged.

Broader treatment options sit in hair and skin, and the compound-selection side across the injectable range.

A note on this section’s history

These products were previously filed under a diabetes heading, which was simply wrong — none of them treat diabetes. The category has been corrected. If you arrived from an old link it will have redirected you here.

Frequently asked questions

Is dutasteride stronger than finasteride?
It suppresses DHT more completely because it blocks both isoenzymes rather than one.

How long does it stay in the system?
Months. The terminal half-life is measured in weeks, against hours for finasteride.

Is it licensed for hair loss in the UK?
No. It is licensed for benign prostatic hyperplasia; hair-loss use here is off-label.

Will it protect hair on a DHT-derived compound?
No. There is no conversion step to block, exactly as with finasteride.

What is the tamsulosin combination for?
Benign prostatic hyperplasia. Tamsulosin relaxes smooth muscle and does nothing for hair.