Finasteride for Hair Loss: How It Works, What to Expect, and Is It Safe?
If you have spent any time researching hair loss treatments, you have almost certainly come across Finasteride. It is the most widely discussed, heavily debated, and clinically proven medication for male pattern baldness available today.
Despite its proven track record, there is a significant amount of misinformation surrounding Finasteride online. Men are often caught between two extremes: clinics claiming it is a miracle cure with zero downsides, and internet forums warning of permanent, life-ruining side effects.
At Magna Health, we believe in giving our patients the complete, unvarnished truth. As a doctor-led clinic that has treated thousands of New Zealand men, we have seen first-hand what Finasteride can do, who it works for, and what the actual risks are. Here is the science-backed reality of Finasteride for hair loss.
The Science: Why Hair Falls Out and How Finasteride Stops It
To understand how Finasteride works, you first need to understand why male pattern baldness (androgenetic alopecia) happens.
The primary culprit behind male hair loss is a hormone called Dihydrotestosterone (DHT). DHT is a byproduct of testosterone, converted by an enzyme called 5-alpha reductase. In men who are genetically predisposed to hair loss, the hair follicles on the top of the scalp are highly sensitive to DHT. When DHT binds to these follicles, it causes them to shrink over time—a process known as follicular miniaturisation [1]. As the follicles shrink, the hair they produce becomes thinner, shorter, and lighter, until the follicle eventually stops producing hair altogether.
This is where Finasteride comes in. Finasteride is a 5-alpha reductase inhibitor. It works by blocking the enzyme that converts testosterone into DHT [2]. By taking Finasteride, you can lower the DHT levels in your scalp by up to 60 percent, effectively starving the process that causes your hair follicles to shrink [3].
It is important to note that Finasteride does not cure hair loss; it manages it. It acts as a shield, protecting your follicles from DHT. If you stop taking the medication, your DHT levels will return to normal, the miniaturisation process will resume, and you will eventually lose the hair that the medication was protecting.
What the Clinical Data Actually Says:
When it comes to efficacy, the clinical data on Finasteride is unequivocal. It is one of only two medications approved by the FDA (and Medsafe in New Zealand) specifically for the treatment of male pattern hair loss.
In landmark long-term studies, the results are consistently positive:
• Stopping further loss: Clinical trials show that 1mg of Finasteride daily halts further hair loss in approximately 83 to 90 percent of men [4].
• Regrowing hair: Over a two-year period, approximately 66 percent of men taking Finasteride experienced visible hair regrowth [4].
• Long-term durability: A 10-year study of men taking Finasteride found that 86 percent of participants maintained or improved their hair count over the entire decade [5].
The medication is most effective at the crown and mid-scalp, though it can also help stabilise a receding hairline. However, the golden rule of hair loss treatment applies here: early intervention is critical. Finasteride is highly effective at saving the hair you have and reviving follicles that have recently begun to shrink. It cannot bring a completely dormant, dead hair follicle back to life.
Addressing the Elephant in the Room: Side Effects
The most common reason men hesitate to start Finasteride is the fear of sexual side effects. It is a valid concern, and one that requires an honest look at the clinical data rather than internet anecdotes.
Because Finasteride alters hormone levels by reducing DHT, it can cause side effects in a small percentage of users. According to the clinical trials and Medsafe data, approximately 1 to 2 percent of men experience sexual side effects, which can include a decreased libido, erectile dysfunction, or a decrease in the volume of ejaculate [6].
For the vast majority of men who do experience these side effects, the issues resolve completely once they stop taking the medication. In many cases, the side effects even subside with continued use as the body adjusts to the medication [6].
There have been rare reports of "Post-Finasteride Syndrome" (PFS), where patients claim sexual or psychological side effects persist long after stopping the drug [7]. While these reports are taken seriously by medical regulators, the incidence rate is exceptionally low, and the causal link remains a subject of ongoing medical study.
For 98 percent of men, Finasteride is a well-tolerated, daily medication that works quietly in the background to protect their hair.
Topical vs. Oral Finasteride
Traditionally, Finasteride has been prescribed as a 1mg oral tablet taken daily. However, recent advancements in compounding pharmacy have made topical Finasteride increasingly popular.
Topical Finasteride is applied directly to the scalp, often combined with Minoxidil. The goal of the topical application is to deliver the DHT-blocking medication directly to the hair follicles where it is needed, while minimising the amount of the drug that enters the systemic bloodstream [8].
For men who are particularly concerned about the risk of systemic side effects, or who have experienced mild side effects on the oral tablet, a compounded topical formulation can be an excellent alternative. Clinical studies have shown that topical Finasteride can significantly decrease the rate of hair loss and improve hair density, with a lower risk of systemic absorption compared to the oral pill [8].
Is Finasteride Right for You?
Finasteride is the most powerful tool available for stopping male pattern baldness, but it is a prescription medication, not a cosmetic supplement. It requires a medical assessment to ensure it is safe and appropriate for your specific health profile.
It is also a long-term commitment. Hair grows slowly, and it typically takes three to six months of consistent use before you will see visible changes in hair density.
If you are noticing the early signs of thinning, increased shedding, or a receding hairline, its worth looking into treatment. The hair you have today is easier to keep than the hair you have already lost is to regrow.
Ready to take control of your hair loss? At Magna Health, our registered New Zealand doctors specialise in clinically proven hair loss treatments, including tailored Finasteride formulations. Complete our free, confidential online assessment today to find out if treatment is right for you, and get a personalised plan delivered discreetly to your door.
Start your free assessment at getmagna.co.nz
References
[1] PubMed. (1998). Finasteride in the treatment of men with androgenetic alopecia. https://pubmed.ncbi.nlm.nih.gov/9777765/ [2] StatPearls. (2024). Finasteride. https://www.ncbi.nlm.nih.gov/books/NBK513329/ [3] PubMed. (2021). Finasteride for hair loss: a review. https://pubmed.ncbi.nlm.nih.gov/34291720/ [4] Journal of the American Academy of Dermatology. (1998). Finasteride in the treatment of men with androgenetic alopecia. https://www.sciencedirect.com/science/article/pii/S0190962298700076 [5] OA Text. (2019). Long-term (10-year) efficacy of finasteride in 523 Japanese men with androgenetic alopecia. https://www.oatext.com/Long-term-(10-year)-efficacy-of-finasteride-in-523-Japanese-men-with-androgenetic-alopecia.php [6] Mayo Clinic. (2026). Finasteride (oral route) - Side effects. https://www.mayoclinic.org/drugs-supplements/finasteride-oral-route/description/drg-20063819 [7] Medsafe. (2016). Post-Finasteride Syndrome. https://medsafe.govt.nz/profs/PUArticles/March2016/PostFinasterideSyndrome.htm [8] JMIR Dermatology. (2026). Patient Satisfaction, Side Effects, and Other Reactions Reported by Adult Men Prescribed Compounded Topical Finasteride via a National Telehealth Platform. https://derma.jmir.org/2026/1/e84676/