Dutasteride has been patented by GlaxoSmithKlein (GSK) in order to treat the benign prostatic hypertrophy symptoms. Then, the drug has been put on the market under the name “Avodart”.

The role of Dutasteride in the cure against hair loss is ambiguous: this drug is not approved to treat Androgenic Alopecia in Europe (Italy included) and in the USA, but it is approved in Japan since 2015 and in South Korea since 2009. In the Usa and in Europe the institutions that manage the matter, respectively FDA and EMA, authorise the use of this drug for the cure of the benign prostatic hypertrophy.


Which is the effect of Dutasteride on hair?

The functioning of Dutasteride on hair is similar to the one of other approved drugs, such as Finasteride, or of anti-DHT natural supplements (the most effective is Serenoa Repens). The real difference between Dutasteride and the other products is the intensity of the effect. Dutasteride inhbits the tranformation of testosterone into DHT, just like Finasteride does, but with a definitely higher reduction level (around 94%). The decrase of DHT amount cures the benign prostatic hypertrophy but also opposes to hair loss. In fact, it is the presence of DHT that causes the hair follicular miniaturisation in people affected by androgenic alopecia.

There are not many studies about Dutasteride, if not for the cure of benign prostatic hypertophy. In particular, there are only 2 specifically focused on the effects of this drug on alopecia.

The first one has been carried out in Korea in 2006 and then pubblished on the Journal American Accademy Dermatology. The result of the study is that Avodart was more or less effective against alopecia depending on the dosage that veried between 0,05 mg and 2,5 mg per day. Three years later, in Korea, a dosage of 0,5 mg per day for the treatment of alopecia was approved, the same dosage used for the treatment of benign prostatic hypertrophy.

The second study took place in Korea again and saw the partecipation of 712 men with different Norwood levels of hair loss. The study has lasted 4 years, between 2009 and 21013, and at the end was pubblished on the magazine Annales of Dermatology.

The result of the study is that Dutasteride was well tollerated if assumed with a dosage of 0,5 mg per day. The side effects, if incurred, have disappeared at the end of the study suspending the assumption of the drug.

In the case of Dutasteride, the approved dosage for the cure of alopecia is the same one for the cure of benign prostatic hypertrophy. This information may seem weird if we think about the fact that other drugs present different dosages for the two different purposes. For example, 1 mg of Propecia is used for hair and 5 mg of Proscar for the prostate. It is hard to deeply analyse the different dosages of Dutasteride in the treatment of androgenic alopecia, since Dutasteride is not approved in Europe and in the USA and that online it is hard to find information about the approved dosages in the East. Digging a little bit, however, it is possible to find out that on the japanese market, where Dutasteride is approved, there is a drug, always produced by GlaxoSmithKlein and called Zagallo, that is available in 2 different dosages: 0,5 mg and 0,1 mg. The choice to put Zagallo on the market also in the version of 0,1 mg suggest the idea that Japan understood that the 0,5 mg dosage, the same one for the treatment of benign prostatic hypertrophy, is too high. Although the low dosage of Dutasteride, this drug is still not approved in Italy.


Dutasteride side effects

Also Avodart, just like any other drug on the market, can cause side effects. It is important to underline that these are just unfortunate and rare exceptions. Moreover, most of the side effects disappear in a little while after the suspension of the drug. Dutasteride inhibits the enzyme 5-alfa reduttasi and so causes the same possible side effects of the drugs of the same type. Here are the main:

  • The most frequent sides are defined “common” and mainly affect the sexual sphere: e. D., difficulty in ejaculating, libido decreased and lower amount of seminal fluid. In addition to these, there is the enlargement of the masculine breast, the gynaecomastia. These sides show in around 1 subject in 10.
  • Less frequent are the so called “not common effects”, such as hair loss from the rest of the body due to the changed level of androgens. This side effect shows in around 1 subject in 100.
  • Among the side effects we need to include the immune reactions of the organism, like the hypersensitivity to the active substance or allergies. These can incur using any drug and can be more or less severe.
  • Since Dutasteride has a great capacity to inhibit the DHT production and since it takes action in particular on the isoform 1 of the enzyme, its assumption may cause side effects on the brain neurosteroids. In fact, the isoform 1 is particularly present in the nervous system and in the brain. The consequences of this action is a kind of brain fog that causes impaired concentration. About this side effect, a specific study that proves its existence has never been carried out. So, it is an open and controversial issue.
  • The enzyme inhibited by Dutasteride is present also in the sebaceous glands. So, one consequence of the action of the drug can be hair dryness and a feeling of straw hair due to the reduction in the sebum production.


A long half-life

The time of disposal of Dutasteride, after its assumption, is pretty long. Up to 6 months may be necessary in order not to present any trace of it in the organism anymore. This happens because Dutasteride time of half-file, the time required in order to halve the concentration of the active substance in the organism, is of around 4 weeks, while Finasteride only needs 6-8 hours. This feature of Dutasteride is clearly a limit, especially for those who are affected by its side effects: ever if they immediately end the assumption, they will keep on having a certain amount of it in the blood for weeks and so they will keep on suffering from the side effects. So, it is true that Dutasteride is more effective in deleting DHT, but, at the same time, is much harder to dispose of.



Another aspect to keep into account if you decide to assume Dutasteride is that it gets metabolized by the liver. This does not mean that the drug is dangerous for the liver, but for sure suggests that who suffers from hepatic impairment should not take it.


Action of the drug

Dutasteride in able to inhibit both the isoform 1 and the 2 of the 5-alfa-reduttasi enzyme. For this reason it is called a “second generation” inhibitor. Because of this feauture, Dutasteride can inhibit the enzyme much more than Finasteride, that takes action only on the isoform 1, can. In addition to the fact that Dutasteride inhibits both the forms, it also seems that his inhibitory power is higher, up to 100 times more than Finasteride on the isoform 1 and around 3 times on the isoform 2. The task of the 5-alfa-reduttasi enzyme is to transform the testosterone into DHT, diidrotestosterone, the hormone responsable for the benign prostatic hypertrophy. By inhibiting this enzyme, Dutasteride and Finasteride have the indirect effect to reduce the DHT production. Dutasteride reduces even more than 90% of its production, while Finasteride only 60%-70%.


Where can I buy Dutasteride?

Dutasteride has to be bought in the pharmacy under medical prescription, since it is a strong drug with many possible side effects. It will be on a white prescription if off label, on a red one if for the treatment of the benign prostatic hypetrophy. Since the GSK license expired in 2015, on the market there are many equivalent generic drugs, produced by important companies such as Teva, EG, Sandox, Mylan etc.


How to use Dutasteride

In Italy, Avodart and the generic drugs with Dutasteride are approved only for the treatment of the benign prostatic hypertrophy with a 0,5 mg daily dosage. This amount corresponds to a soft capsule, the form in which it is present on the market, of Avodart. The soft capsules contain the active substance in liquid form and wrapped in a soft gelatine shel. The fact that the active substance is in the liquid form represents a disadvantage for those who whises to take it off label. In fact, if you try to reduce the dosage of the capsule by dividing it, it would lose its efficency. Instead, who uses Proscar as a replacement for Propecia, can easly divide it in 4 or 5 parts. Another difficulty is due to the absence of an official dosage. Taking an incorrect amount, many side effects can occur.


Warnings and precautions about Dutasteride


It is extremely important that pregnant women do not touch Dutasteride. Touching even just one capsule may lead to damages of the fetus, since the drug can be absorbed through the skin. In particular, it can cause a malformation of the fetus’ genitalia.  Traces of Dutasteride are also present in the semen of who is assuming it, so pregnant women should avoid having unprotected sex with someone that is assuming it. It is also important to avoid donating blood if you are assuming the drug, in order to avoid its transmission to pregnant women.

To avoid genital malformations, children and teenagers do not have to come into contact with Dutasteride.


PSA Monitoring

If you have planned to undergo an analysis to detect prostate cancer, it is opportune to tell the doctor and suspend Dutasteride assumption 2 months before. In fact, Dutasteride, just like Finasteride, provokes a 50% decrease of the specific prostatic antigen serum concentration, used as a screening for the cancer diagnosis. If you are taking Dutasteride, the result of the analysis may be distorted.


Dutasteride interaction with other drugs  

We said that Dutasteride gets metabolized by the liver. The enzyme that makes it possible is called CYP3A4. Taking Avodart you have to pay attention not to take other drugs that inhibits this enzyme, such as antidepressants (nefadozone) or antivirals (itraconazolo, ritonavir, indinavir, ketoconazolo etc). If the CYP3A4 is inhibited, it will not be able metabolize Dutasteride and so it will keep on circulating in the body causing more side effects.


Conclusions about Dutasteride

We saw that the assumption of Dutasteride has advatages and disadvantages. The most positive aspect of the drug is its high power in fighting hair loss, since it is the most effective drug in inhibiting the 5-AR enzyme. On the other hand, it can cause many long lasting and annoiyng side effects, especially if taken in an high dosage. Although, if the dosage is reduced, the benefits are reduced too and at that point it does not make sense to prefer Dutasteride to Finasteride. The ideal solution would be to find a well balanced dosage with the doctor in order to obtain the maximum benefits possible with the less side effects.

Our advice is, in any case, to follow the ufficial line. Finasteride is a good anti-DHT drug, specifically approved for hair loss and with widely evaluated results. If you really want to take the risk of starting an Avodart cure, we widely suggest to do so turning to a doctor. It is a heavy drug that if wrongly assumed can cause many problems.