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Dutasteride (avodart) is a dual 5-a reductase inhibitor that inhibits conversion of testosterone to DHT. It was developed to treat benign prostatic hyperplasia (BPH), which is the enlargement of the prostate. Bodybuilders have used this compound to protect themselves from hair loss.

dutasteride chemical structure

Dutasteride Chemical Structure

Table of Contents


History and finasteride comparison

Dutasteride is a 2nd generation 5alpha reductase inhibitor, the 1st being finasteride. It was developed by drug company GlaxoSmithKline (GSK) for BPH in the early 2000's.

The difference between dutasteride, and finasteride, is in the name: Dutasteride (dual-tasteride) works on both of the 5a-reductase enzymes, while finasteride works on just one. Dutasteride has greater efficacy because of this, and it is more powerful at a lower dose.

How it works and DHT

To understand how dutasteride works we must first learn about DHT. Dihydrotestosterone (DHT) is a sex steroid and androgen hormone. The enzyme 5a-reductase synthesizes DHT in the testes, hair follicles, adrenal glands, and prostate. Reductase inhibitors work by blocking the action of the enzymes that convert testosterone to DHT. This is why they work so well for protecting/re-growing head hair and helping with BPH. Dutasteride stacked with finasteride can lower DHT in the body up to 95%.


When bodybuilders use anabolic-androgenic steroids, it can speed up head hair loss. This is due to increased testosterone hormones in the body. The more testosterone, the more conversion to DHT in the body. In addition, running DHT derivatives such as masteron, winstrol, or proviron will further increase DHT. To combat this, bodybuilders have experimented with 5a-reductase inhibitors, such as dutasteride, to protect their existing hair and even re-grow more. However, this can come at a price and a myriad of side effects.

dutasteride avodart

Dutasteride (Avodart) GSK


Dutasteride has been used for acne control, as it will lower an overabundance of androgens in the body. Nonetheless, it's not a very effective anti-acne drug, and its potential side effects aren't worth the possible acne control.

Side Effects

Preventing sex hormone DHT from being converted from testosterone might not be the best idea in the long term. If you care about your sex drive, dutasteride might not be for you. The two main side effects from this drug are 1) erectile dysfunction (ED) 2) decreased sexual desire (libido). Additional side effects like gynecomastia (bitch tits) can occur as well, due to severely low DHT levels. Even with short term use at low dosages, some users have reported serious problems problems with ED. Therefore, the user must be extremely careful when using duta, and use it only if absolutely necessary.

Dosage and Half-Life

A dosage of 2.5mgs per day is a popular starting point among bodybuilders. Most guys are splitting the dose into AM/PM, but that's not necessary. The half-life of dutasteride is very long – up to 5 weeks. So, you can dose it EOD (every other day) or longer if you wish.


Dutasteride is a potent inhibitor of 5a-reductase enzyme, which will block testosterone conversion to DHT. It helps with BPH. In addition, for bodybuilders, it will aid in keeping/regrowing head hair. It can have severe long term side effects, even when used for short periods of time, so use at your own risk.


Want to read about Dutasteride on our forums? check out these threads:


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Written by
Steve Smi (Also known as Steve Smith), has over 12 years of experience in the bodybuilding and fitness industry. He's the co-Host of the popular Evolutionary Radio Podcast - over 500,000 listens! He has been a personal trainer and writer for the last 10 years with over 1000 articles written. He's been a moderator on forums for over 10 years. Steve holds the following certifications and records: NASM Personal Trainer NASM Fitness Nutrition Specialist Florida Local Powerlifting champion Top writer for 2019 Fitness rated

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