How Dutasteride Works, Results, Usage, and Side Effects

Hair loss, medically termed as androgenetic alopecia (AGA), is a widespread concern impacting countless individuals worldwide. The chief culprit behind AGA is dihydrotestosterone (DHT). Dutasteride, a dual 5α-reductase inhibitor, has garnered significant attention for its potential in arresting hair loss by attenuating DHT synthesis. This in-depth article elucidates the scientific underpinnings of dutasteride’s mechanism and reviews key studies highlighting its effectiveness.

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What is Dutasteride?

Dutasteride is a medication primarily used to treat benign prostatic hyperplasia (BPH), a condition characterized by an enlarged prostate gland in men. It belongs to a class of drugs known as 5-alpha-reductase inhibitors. Dutasteride works by inhibiting the activity of the enzyme 5-alpha-reductase, which is responsible for converting testosterone into dihydrotestosterone (DHT) in the body. DHT is a hormone that can contribute to the growth of the prostate gland. By reducing DHT levels, dutasteride helps shrink the prostate, relieving urinary symptoms associated with BPH. Additionally, dutasteride has been investigated as a potential treatment for male pattern baldness (androgenetic alopecia) due to its ability to reduce DHT levels in the scalp. However, its use for hair loss is typically off-label and not approved by regulatory agencies for this purpose in many countries.

History of Dutasteride

Dutasteride, a medication primarily used for treating benign prostatic hyperplasia (BPH) and, to some extent, male pattern baldness (androgenetic alopecia), has an interesting history. It is a member of the class of drugs known as 5-alpha-reductase inhibitors, and its development is closely linked to that of another similar medication, finasteride.

The story of dutasteride begins with the recognition of the role of dihydrotestosterone (DHT) in both BPH and male pattern baldness. DHT is a hormone derived from testosterone and is believed to contribute to the growth of the prostate gland in BPH and the miniaturization of hair follicles in androgenetic alopecia. Researchers sought ways to inhibit the conversion of testosterone into DHT to address these conditions.

In the late 20th century, finasteride was developed as the first FDA-approved medication in the 5-alpha-reductase inhibitor class. It was approved for the treatment of BPH and later for male pattern baldness. However, it selectively inhibits only one of the two isoforms of the 5-alpha-reductase enzyme, known as type II.

Dutasteride, on the other hand, inhibits both type I and type II isoforms of 5-alpha-reductase, making it a more potent inhibitor of DHT production. The development of dutasteride as a potential treatment for BPH and androgenetic alopecia followed the success of finasteride. Dutasteride was approved by the FDA for the treatment of BPH in 2001 under the brand name Avodart. Its effectiveness for male pattern baldness, while demonstrated in some studies, has led to off-label use in some countries.

The history of dutasteride highlights the ongoing efforts to find effective treatments for conditions influenced by DHT, such as BPH and hair loss. Its dual inhibition of 5-alpha-reductase isoforms has expanded the options available to individuals seeking relief from these conditions, but its use for hair loss remains a subject of ongoing research and discussion.

The Role of DHT in Androgenetic Alopecia

Dihydrotestosterone (DHT) is a hormone derived from testosterone, and it plays a significant role in hair loss, particularly in androgenetic alopecia (male and female pattern baldness). In individuals with a genetic predisposition to hair loss, hair follicles in certain areas of the scalp are sensitive to DHT. When DHT binds to receptors in these follicles, it can lead to a process known as miniaturization. This process causes the hair follicles to shrink over time, resulting in thinner and shorter hair growth cycles. Eventually, the affected follicles may stop producing hair altogether, leading to baldness in those areas. Therefore, DHT is a key factor in the development and progression of hair loss, and treatments often target its effects to mitigate or reverse the condition.

How Dutasteride Works

Dutasteride works for hair loss, specifically male pattern baldness (androgenetic alopecia), by targeting the underlying cause of this condition, which is the hormone dihydrotestosterone (DHT). Here’s how it works:

  • DHT Production Inhibition: In individuals with male pattern baldness, hair follicles in certain areas of the scalp are genetically predisposed to be sensitive to DHT, a hormone derived from testosterone. DHT has been shown to miniaturize hair follicles, leading to the production of shorter, finer hair and, eventually, the cessation of hair growth. Dutasteride inhibits the action of the enzyme 5-alpha-reductase, which is responsible for converting testosterone into DHT in the body. By reducing DHT levels in the scalp, dutasteride helps slow down the miniaturization of hair follicles.
  • Maintenance and Regrowth: By reducing DHT levels, dutasteride can help maintain existing hair and potentially promote regrowth of hair in areas where follicles have not yet ceased functioning. This can lead to an increase in hair density and improved coverage on the scalp.
  • Broader 5-alpha-reductase Inhibition: One key difference between dutasteride and another medication used for male pattern baldness, finasteride, is that dutasteride inhibits both type I and type II isoforms of the 5-alpha-reductase enzyme. Finasteride only inhibits the type II isoform. This broader inhibition of 5-alpha-reductase by dutasteride results in a more significant reduction in DHT levels, making it a potent option for individuals who do not respond well to finasteride or have a more aggressive form of hair loss.

It’s important to note that while dutasteride has shown promise in the treatment of male pattern baldness, its use for this purpose is often off-label, meaning it may not be officially approved by regulatory agencies in many countries.

Empirical Evidence

  • Olsen et al. (2006): A comprehensive study involving 416 men highlighted a dose-dependent increase in hair count. Notably, participants on higher doses exhibited remarkable improvements, shedding light on dutasteride’s potency.
  • Jung et al. (2014): In this investigation, a noteworthy increase in hair density was observed, reinforcing the drug’s clinical effectiveness.
  • Tsai et al. (2016): This study juxtaposed dutasteride against finasteride, another 5α-reductase inhibitor. While both medications manifested improvements, dutasteride’s superiority in terms of hair count and patient satisfaction was undeniable.
Clinical trial results of dutasteride compared to a placebo and finasteride

Clinical trial results showing improved hair growth for 0.02mg, 0.1mg, and 0.5mg of dutasteride compared to 1mg of finasteride and a placebo.


The results of dutasteride for hair loss can vary from person to person, and it’s important to note that the use of dutasteride for this purpose is often off-label, meaning it may not be officially approved for treating male pattern baldness (androgenetic alopecia) by regulatory agencies in many countries. Here are some potential results and considerations:

  • Maintenance of Existing Hair: Dutasteride can be effective in slowing down the progression of male pattern baldness by reducing levels of dihydrotestosterone (DHT), a hormone linked to hair follicle miniaturization. This can help in maintaining existing hair and preventing further hair loss.
  • Hair Regrowth: In some individuals, dutasteride may promote hair regrowth in areas where hair follicles have not yet ceased functioning. This can lead to an increase in hair density and improved coverage on the scalp.
  • Variable Responses: The effectiveness of dutasteride varies among individuals. Some people may experience significant improvements in hair density and thickness, while others may have more modest results. Response to treatment can depend on factors such as the severity of hair loss, individual genetics, and the duration of use.
  • Slower Progression: Even if complete hair regrowth is not achieved, dutasteride can help slow down the progression of hair loss, allowing individuals to maintain a more stable and cosmetically satisfactory appearance.
Before and after showing improved results of using dutasteride

Improved hair growth and density after continued use of dutasteride.

How to Use

Dutasteride is a prescription medication that may be used off-label to treat male pattern baldness (androgenetic alopecia). If your healthcare provider recommends dutasteride for hair loss, here are some general guidelines for its use:

  • Consultation with a Healthcare Provider: Before starting dutasteride or any prescription medication, schedule a consultation with a healthcare provider or dermatologist who specializes in hair loss. They will assess your condition, provide a proper diagnosis, and discuss treatment options.
  • Prescription: If dutasteride is deemed appropriate for your situation, your healthcare provider will prescribe the medication. Follow their instructions carefully.
  • Dosage: The typical dosage for treating hair loss with dutasteride is 0.5 milligrams (mg) per day. It is usually taken as a single oral capsule. Follow the specific dosage and administration instructions provided by your healthcare provider.
  • Consistency: Take dutasteride consistently at the same time each day. This helps maintain steady levels of the medication in your system.
  • Duration: Hair loss treatments often require patience. It may take several months before you start noticing significant improvements in hair density or regrowth. Be prepared for a long-term commitment to the treatment.
  • Monitor Side Effects: While taking dutasteride, monitor yourself for any potential side effects. Common side effects may include sexual side effects such as decreased libido, erectile dysfunction, and decreased ejaculate volume. If you experience any concerning side effects, discuss them with your healthcare provider.
  • Regular Follow-Up: Your healthcare provider will likely schedule regular follow-up appointments to monitor your progress and assess the effectiveness of the treatment. These appointments are essential for tracking your response to dutasteride and addressing any concerns.
  • Patience and Realistic Expectations: Understand that not everyone responds to dutasteride in the same way, and results can vary. Some individuals may experience significant improvements, while others may have more modest outcomes.

Safety and Side Effects

Dutasteride, like many medications, can have potential side effects. It’s important to be aware of these side effects and discuss them with your healthcare provider before starting the medication. Here are some common side effects associated with dutasteride:

  • Sexual Side Effects: Dutasteride can cause sexual side effects in some individuals. These may include a decrease in sexual desire (libido), difficulty achieving or maintaining an erection (erectile dysfunction), and a reduction in the volume of semen during ejaculation. These side effects can be concerning for some people, and it’s important to discuss them with your healthcare provider.
  • Breast Tenderness or Enlargement: Some individuals may experience breast tenderness or breast enlargement (gynecomastia) while taking dutasteride. If this occurs, inform your healthcare provider.
  • Allergic Reactions: While rare, allergic reactions to dutasteride can occur. Symptoms of an allergic reaction may include rash, itching, swelling of the face, lips, tongue, or throat, severe dizziness, or difficulty breathing. Seek immediate medical attention if you experience any signs of an allergic reaction.
  • Other Side Effects: Dutasteride may also lead to other side effects such as headache, dizziness, runny or stuffy nose, and skin rash. These side effects are less common but should be reported to your healthcare provider if they persist or worsen.
  • Depression: In rare cases, some individuals have reported experiencing symptoms of depression while taking dutasteride. If you notice mood changes, feelings of sadness, or other signs of depression, discuss them with your healthcare provider.
  • Liver Function: Dutasteride may affect liver function in some individuals. Your healthcare provider may monitor your liver function through blood tests during treatment.


Dutasteride’s dual inhibitory action against both types of 5α-reductase enzymes positions it as a formidable adversary to AGA. By drastically curtailing DHT levels, it offers a scientifically-backed approach to counter the biochemical triggers of hair loss. Clinical trials consistently underscore its efficacy, solidifying its standing in the pantheon of AGA treatments.

However, the journey to an ideal therapeutic solution is laden with intricacies, and while dutasteride offers hope, its potential side effects necessitate a well-informed and cautious approach.


  • Olsen, E. A., et al. (2006). Dual 5α-reductase inhibition in male pattern hair loss: Results of a randomized study. Journal of the American Academy of Dermatology, 55(6), 1014-1023.
  • Jung, J. Y., et al. (2014). Dutasteride in men with AGA recalcitrant to finasteride. International Journal of Dermatology, 53(11), 1351-1357.
  • Tsai, T. F., et al. (2016). A comparative study: Finasteride vs. dutasteride. Journal of Dermatological Science, 81(2), 183-188.

Note: Always seek professional medical advice before starting any treatment.

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