Written by
Science & Humans
Testosterone therapy helps replace deficits which is essential for the well being of a male, especially as they get older and testosterone synthesis starts tapering down. Testosterone therapy effectively counters hypogonadism or low – T.
Long term external replacement of testosterone might lead to an excess production of DHT(Dihydrotestosterone) which shrinks hair follicles eventually leading to hair loss. A genetic disposition to MPB (Male Pattern Balding) is the leading cause for a thinning crown and a receding hairline. But being proactive and starting early treatment will help reverse this condition.
Finasteride, a 5AR blocker blocks the enzyme called Type -II Alpha Reductase that synthesizes DHT from testosterone. More 5AR enzyme, more DHT, leading to MPB hair loss.
Minoxidil, which is a scalp treatment, helps increase blood flow to the hair follicles. Together finasteride and Minoxidil help regrowth of hair, and keep a good mane.
The quarterly follow ups will help manage side effects if any. Finasteride has been well studied, with long term and short term side effects very well researched and considered safe for treating hair loss.
Finasteride is Health Canada approved.
Why is only Finasteride prescribed and not Dutasteride for people undergoing Testosterone Therapy ?
Finasteride was discovered and patented a few decades earlier to Dutasteride. While dutasteride is as good and has similar side effects it is a recent drug and not enough studies or long term usage data to be approved by FDA.
Currently Dutasteride for hair loss is only an ‘off label’ prescription but is not allowed by Health Canada.
Finasteride and Dutasteride – what is different?
- Finasteride blocks type-II 5AR while Dutasteride blocks both Type – I and Type -II 5AR enzymes, this is one reason it is considered potent.
- Fnasteride effectively blocks 70% of DHT while Dutasteride blocks more than 80%
- Half life – Finasteride lasts in the system for a day, while Dutasteride lingers for longer time.
It is important to remember that DHT is removed not only from the scalp but from all other tissues as well. In this context is it wise to take dutasteride which is too efficient in removing DHT?
DHT in the scalp might be bad for hair, but it has a role to play in other tissues. Muscle tone for instance. Synthesizing of estradiol is another reason. Can eliminating DHT increase estradiol which can result in more body fat? Being mindful of such cascading side effects is another reason finasteride is favored over dutasteride.
The anabolic and androgenic factors of testosterone therapy are much more potent in DHT. It is DHT which is responsible for the development of male sexual features in the womb, and later in puberty secondary sexual characteristic features like deepening of the voice, pubic hair development etc.
And yes, when we credit testosterone with the good things of mood upliftment, good muscle tone, libido, it is actually DHT that is doing the heavy work. Everyday about 10% of testosterone is converted into DHT.
Hormone optimization does not mean just replacement but carefully monitoring all side effects including the likelihood of hair loss and preventing it as well. It is achieving balance as close to nature intended.
Regular blood work & quarterly check ups while on testosterone therapy is emphasized for this reason.
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FAQs
What is testosterone therapy and why is it essential for aging men?
Testosterone therapy involves the external replacement of testosterone to counteract the natural decline in endogenous synthesis that occurs as men age. Adequate testosterone levels are critical not only for maintaining muscle mass, bone density, libido, and mood, but also for overall energy and wellbeing. When testosterone production drops below healthy thresholds—a condition known as hypogonadism—men may experience fatigue, depression, loss of muscle tone, and reduced sexual function. By restoring testosterone to optimal levels, therapy alleviates these symptoms and helps preserve the secondary sexual characteristics and physiological processes that testosterone supports.
How can testosterone therapy lead to increased DHT and potential hair loss?
Once administered, exogenous testosterone circulates through the body and is converted by the TypeII 5alpha reductase (5AR) enzyme into dihydrotestosterone (DHT). While DHT is responsible for many beneficial androgenic effects—such as supporting libido, muscle tone, and mood—it can accumulate in the scalp and cause miniaturization of hair follicles. Over time, this follicular shrinkage manifests as thinning hair, a receding hairline, or a thinning crown, particularly in individuals genetically predisposed to male pattern balding (MPB).
What genetic factors contribute to male pattern balding?
Male pattern balding (MPB) is primarily driven by genetic sensitivity of scalp hair follicles to DHT. Even normal levels of DHT can trigger follicular miniaturization in individuals carrying androgen receptor gene variants that heighten follicle susceptibility. Those with a family history of MPB are at greater risk, and the pace and pattern of hair loss—typically a receding hairline and balding at the crown—are largely determined by inherited factors. Early intervention in testosterone treated patients with genetic predisposition is key to preventing irreversible follicle damage.
How does finasteride work to prevent hair loss during testosterone therapy?
Finasteride is a selective 5alpha reductase TypeII inhibitor that blocks the conversion of testosterone into DHT. By inhibiting up to 70% of DHT production, finasteride reduces the DHT burden on scalp follicles, helping to stabilize miniaturization and often promote regrowth of thinning hair. Its targeted action means other tissues remain relatively unaffected, preserving the androgenic benefits of testosterone therapy elsewhere in the body. Finasteride’s efficacy and safety have been well documented in both shortterm and longterm studies, and it is approved by Health Canada for treating MPB.
Why is minoxidil used in conjunction with finasteride?
Minoxidil is a topical vasodilator that increases blood flow to hair follicles, enhancing nutrient and oxygen delivery at the follicular level. When paired with finasteride’s DHTreducing effects, minoxidil synergistically supports hair regrowth: finasteride curtails the hormonal driver of follicle miniaturization, while minoxidil revitalizes follicle health and stimulates the dormant follicles to reenter the growth phase. This combination is widely regarded as the most effective nonsurgical regimen to restore and maintain a healthy head of hair in men undergoing testosterone therapy.
What are the safety considerations for finasteride and minoxidil?
Both finasteride and minoxidil have been extensively studied. Finasteride’s side effects are generally mild and may include decreased libido, erectile dysfunction, or mood changes, with most cases resolving upon discontinuation. Minoxidil’s topical application can sometimes cause scalp irritation or itching. Regular quarterly followups with blood work and clinical evaluation allow clinicians to monitor hormone levels, DHT suppression, and any emerging side effects, ensuring therapy remains both effective and safe over the long term.
Why is finasteride preferred over dutasteride during testosterone therapy?
Although dutasteride inhibits both TypeI and TypeII 5AR enzymes—blocking over 80% of DHT production compared to finasteride’s 70%—it also reduces DHT in all tissues more broadly and has a much longer halflife. This potent, systemic DHT suppression raises concerns about unintended effects on muscle tone, estradiol synthesis, and metabolic balance. Furthermore, dutasteride lacks longterm safety data in the context of male hormone optimization and is not approved by Health Canada for hair loss; its use remains offlabel. Finasteride’s established safety profile, more controlled DHT suppression, and regulatory approvals make it the standard choice.
How is hormone balance and hair health monitored during treatment?
Effective hormone optimization requires vigilant monitoring of both systemic and hairrelated outcomes. Patients on testosterone therapy with concurrent finasteride and minoxidil undergo regular blood panels—typically every three months—to assess testosterone, DHT, estradiol, and other relevant markers. Clinicians also perform scalp examinations to document hair density and coverage. This comprehensive approach ensures testosterone levels stay within desired ranges, DHT remains sufficiently suppressed to protect follicles, and any side effects are identified and managed promptly, achieving a balance “as close to nature intended.
