Tag Archive for: testosterone

Low-Level Laser Light Therapy for Androgenic Alopecia

Woman looking at her scalp closely for hair growth. Laser light therapy can help stimulate and boost hair growth, especially when used alongside a prescription hair growth treatment.

Data from the American Hair Loss Association shows that androgenic alopecia accounts for more than 95% of men and 40% of women over age 50. (01) So, if you’re dealing with hair loss, the chances that your condition is due to androgenic alopecia are high. Fortunately, in the battle against hair loss, there are a variety of strategies to choose from. One such option is low-level laser light therapy. 

Understanding How Androgenic Hormones Affect Hair Follicles

Androgenic alopecia, also known as pattern baldness, is the most prevalent type of hair loss in both men and women. The condition is primarily caused by the influence of androgenic hormones on hair follicles.

How DHT Relates to Hair Loss 

Testosterone and dihydrotestosterone (DHT) are examples of androgen hormones that play a crucial role in developing and regulating secondary sexual characteristics in both sexes. After all, humans would not be able to procreate without these hormones! However, when it comes to hair follicles, DHT can have a detrimental impact.

In individuals genetically predisposed to androgenic alopecia, hair follicles become more sensitive to the effects of androgens. DHT binds to receptors in the hair follicles, leading to an unwanted process known as miniaturization.

Miniaturization is the gradual shrinking of hair follicles over time. This process shortens the hair growth cycle, resulting in thinner, weaker hair strands. Eventually, these hairs may stop growing altogether. As a result, affected individuals experience a receding hairline, a more visible crown, or overall hair thinning. (02)

The exact mechanisms by which androgens cause miniaturization remain unknown. One theory suggests that DHT disrupts the natural growth cycle of hair follicles, shortening the anagen (growth) phase and lengthening the telogen (resting) phase. This disrupts the balance between hair growth and shedding, eventually leading to hair loss. (02)

Another theory hypothesizes that DHT may affect the hair follicle’s nutrient supply. Increased production of DHT can reduce the size of blood vessels supplying the hair follicles. The shrunken vessels cannot deliver adequate oxygen and nutrients, making the starved hair follicles more susceptible to miniaturization. 

Whatever the cause of androgenic alopecia, the resulting hair loss is almost always distressing. Understanding how to identify the condition’s specific growth patterns can help individuals seek appropriate treatment as soon as possible. 

Androgenetic Alopecia Growth Patterns in Males and Females 

When it comes to androgenic alopecia, hair loss patterns are distinct. The most common hair loss pattern for men starts with a receding hairline, forming an “M” shape. Hair loss extends to the crown area as the condition progresses, resulting in a thinning or a bald spot. In contrast, female pattern baldness follows a different pattern. Women usually experience overall hair thinning rather than distinct bald spots or receding hairlines. Unlike men, women rarely develop a completely bald scalp. 

What are the Signs of Androgenic Alopecia?

To determine if they are experiencing androgenetic alopecia, individuals should look for specific signs and symptoms. A few signs of androgenic alopecia may include:

  • Gradual hair thinning
  • Excessive hair shedding
  • A widening part line
  • A stark decrease in hair volume
  • Distinct changes in the hair texture (e.g., becoming finer or more brittle)

Keep in mind that other factors, such as stress, vitamin deficiencies, and certain medical conditions, can also contribute to hair loss. Therefore, consulting a healthcare professional can provide an accurate diagnosis and identify the underlying cause. 

So, once you’ve determined that you have androgenic alopecia, the next step is finding the right treatment.

Hair Growth Solutions for Androgenetic Alopecia

Intervening early improves the chances of reducing or halting hair loss. Treatment options for androgenetic alopecia typically include medications like Minoxidil or Finasteride to counter the impacts of DHT. These medications make hair follicles healthier, encouraging robust hair growth. 

Although these medications may be taken orally, pills typically result in more side effects because they are ingested. Topicals, however, target hair follicles directly and usually have fewer negative effects on the rest of the body. Medicated hair growth treatments work best when they’re customized for the individual, which is why working with an experienced hair professional is essential. 

Interestingly, many individuals feel the need to stick to one treatment option at a time. Many may choose medications but opt out of other hair growth treatments while taking the medications. 

But why put all your eggs in one basket? Instead, one way to boost the chances for success is to add another layer of treatment and explore other options — all while undergoing treatment using prescription topical medications. For example, a process that can be utilized alongside prescription topical treatments is low-level laser light therapy.

Stimulating Hair Growth With Laser Light Therapy 

Laser light therapy is also known as low-level laser therapy (LLLT) or red light therapy. This process involves the use of specific wavelengths of light to stimulate hair follicles and promote hair growth. 

FDA-approved since 2007 with red light wavelengths of 650nm-1200 nm, LLLT works well with tissues such as the scalp. Low-level light therapy is based on the principle of photobiomodulation, where light energy is absorbed by cells, triggering biological responses. (03

Is Low-Level Light Therapy Effective? 

Numerous studies have investigated the efficacy of laser light therapy for hair loss. A  study published in Lasers in Surgery and Medicine in 2019 evaluated the effects of laser light therapy on pattern hair loss in both men and women. After 24 weeks of treatment, the laser therapy group exhibited a significant improvement in hair density compared to a group that did not receive light therapy (04).

Furthermore, a review published in the Journal of Dermatological Treatment analyzed data from a 24-week study. The analysis found that laser light therapy significantly increased hair density and hair growth rate in people with androgenetic alopecia (05).

These studies and many others provide promising evidence for the effectiveness of laser light therapy. However, it’s important to note that individual responses may vary, and long-term maintenance treatments may be required to sustain the results.

How Does LLLT Work?

While using light to grow hair might seem like science fiction, the science behind low-level light therapy is undoubtedly real. The low-power lasers or light-emitting diodes (LEDs) used by low-level light therapy stimulate cellular activity and promote healing. And although the exact mechanisms are not yet fully understood, several theories suggest how LLLT can positively impact hair growth and cell turnover, especially on the scalp. 

One proposed theory is that LLLT increases blood flow and nutrient delivery to the hair follicles. The photons emitted by the laser or LED devices are absorbed by the cells in the scalp, leading to increased production of adenosine triphosphate (ATP), the energy source for cellular processes. This heightened ATP production may enhance blood circulation, promoting the supply of oxygen and nutrients to the hair follicles. 

Another theory suggests that LLLT stimulates the production of growth factors and cytokines. These molecules play crucial roles in cell development. By boosting these molecules, LLLT may trigger the hair cycle’s anagen (growth) phase, leading to increased hair growth and density.

Furthermore, LLLT is thought to reduce inflammation and oxidative stress in the scalp. Inflammation and oxidative stress can contribute to hair loss and block cell turnover. By targeting these underlying factors, LLLT may create an environment more favorable for hair follicles to heal and cells to regenerate. In turn, healthier follicles can begin to grow hair. 

Laser Hair Growth Home Formats Available

Perhaps the best reason to incorporate LLLT into your hair growth routine is that it’s safe and easy to use at home. LLLT is considered a very safe and non-invasive option not only for individuals experiencing hair loss but also for people simply seeking to improve the health and quality of their hair. 

While low-level light therapy services can be found at dermatology clinics, these in-office treatments are often extremely costly and time-consuming. However, a home-based LLLT routine can conveniently and safely reduce scalp inflammation and stimulate hair follicles to produce new growth. Personal at-home LLLT treatments allow individuals to see all the benefits of light treatment without the in-office price tag.  

 References: 

(01) https://www.americanhairloss.org/men_hair_loss/introduction.html 

(02) Study on the role of LLLT in adrogenetic alopeica

(03) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6554163/

(04) https://link.springer.com/article/10.1007/s10103-018-02699-9

(05) https://pubmed.ncbi.nlm.nih.gov/23551662/

Your Comprehensive Guide to Oral Dutasteride

Happy Head's dermatologists formulate prescription-grade hair loss treatments with Dutasteride as an active ingredient, made to block hair loss. Learn more about this active ingredient and how it tackles hair loss and prevents future loss while promoting hair growth.

If you’re experiencing male or female pattern baldness, your dermatologist probably recommended a Dihydrotestosterone or DHT blocker. There are a few different types that you may have heard about. Finasteride was the first DHT blocker on the market and the oral version is FDA approved for male pattern hair loss. Dutasteride is a newer medication that’s often used off-label to treat hair loss. If you’re unfamiliar with Dutasteride as a primary ingredient in hair loss treatments then you’re in the right place. We’re going to share everything you need to know about oral Dutasteride in this comprehensive guide and how it can help you achieve successful hair growth. 

Dutasteride is a DHT Blocker

Let’s start with the basics. Both men and women have an enzyme called 5-alpha reductase in their liver and skin. It can also be found in men’s prostates. The enzyme is responsible for converting Testosterone produced into dihydrotestosterone (DHT). Healthy levels of DHT are needed to support sexual development in both men and women. When a person’s DHT level gets too high during adulthood, however, it can cause prostate enlargement in men and hair loss in both men and women. High levels of DHT shrink the hair follicles and shorten the hair growth cycle resulting in hair loss.   

Dutasteride is Designed to Prevent Hair Loss 

DHT blockers like Dutasteride prevent Testosterone from converting into DHT in th

e first place. When production is inhibited, the amount of DHT that can attach to your hair follicles is significantly reduced, limiting the effects on your scalp. 

Dutasteride is a Newer DHT Blocker

Finasteride was the first DHT blocker on the market in 1992. Dutasteride was developed a few years later and patented in 1996. The medication was marketed to treat benign prostatic hyperplasia, another name for enlarged prostates, under the brand name Avodart. In 2015, Dutasteride’s patent expired, making the medication more widely available. Although Dutasteride is not FDA approved for treatment of male or female pattern hair loss and is used off-label in the United States, it has been approved in South Korea since 2009 and Japan since 2015. At Happy Head, every formula we create is thoroughly tested and found to have effective results by our board-certified dermatologists. 

Finasteride and Dutasteride Both Treat Androgenetic Alopecia, but Work Differently

Like Finasteride, Dutasteride inhibits 5a-reductase (5AR). The difference is the number and types of enzymes inhibited. Finasteride selectively inhibits the Type 2 isoenzyme, and Dutastride inhibits both Type 1 and 2. A research study published in the National Library of Medicine on 576 men confirmed that Dutasteride is an effective option for men who don’t respond well to Finasteride. So if you’ve tried Finasteride before without success, just let your Happy Head dermatologist know and they’ll find an effective solution for you or craft one from prescription-grade ingredients just for you. 

Is Dutasteride Stronger 

Than Finasteride?

According to research findings, Dutasteride is a stronger ingredient. In one study on men with Androgenetic Alopecia (male pattern baldness), Dutasteride improved hair growth by over twelve percent after 24 weeks, compared to just seven and a half percent in the group that took Finasteride. However, anecdotally, some dermatologists find that while some patients respond better to Dutasteride, other patients achieve better results with Finasteride. It’s difficult to predict which medication will work better without trying each. 

Dutasteride Has Long-Lasting Effects

Dutasteride remains in your system for a long time after the medication is stopped. It can be detected for up to four to six months after your last dose. In comparison, Finasteride only lasts in your system for five to eight hours. 

Why Not Try Dutasteride First?

When prescribing medications for genetic and other types of hair loss, dermatologists often start with lower strengths and dosages and bump up to higher ones as needed. The system gives you the most effective formulas at the lowest possible dosages to help avoid side effects. After all, Finasteride, which is usually used as a first-line treatment, effectively treats many patients experiencing male and female pattern baldness. Some people never need another DHT blocker. There are times, however, when Finasteride doesn’t do the trick. In those cases, Dutasteride is often prescribed next. 

Are Side Effects Common with Dutasteride?

DHT blockers can cause sexual side effects, such as decreased libido and erectile dysfunction, so some people, especially men, may be hesitant to try them. The truth is that side effects due to Dutasteride are not typical, and most people do not experience them.  According to a study from the National Library of Medicine, eighty-five percent of men who use DHT blockers don’t experience any side effects. Side effects usually dissipate over time after the medication is discontinued.  

What Conditions Does Oral Dutasteride Treat

Dutasteride is most often prescribed to treat male and female pattern hair loss, also known as Androgenetic Alopecia. The condition is genetic and occurs when an overproduction of DHT attacks the hair follicles. Dutasteride stops the flow of DHT to prevent further hair loss and allow new hair to grow. Oral Dutasteride is also prescribed for conditions such as frontal fibrosing alopecia and as appropriate for other forms of alopecia. 

How Long Will It Take to See Results?

Oral Dutasteride may start working immediately, but it will take approximately six months to a year to see a noticeable difference. 

Oral Hair Growth treatments formulated by dermatologists and delivered to your door using Dutasteride, Finasteride, Minoxidil, and more.

Can Oral Dutasteride Be Combined With Minoxidil and Other Hair Loss Treatments?

Not only can Dutasteride be combined with Minoxidil, but it is also recommended. The two medications work differently and together can maximize your hair growth. Here’s how. When people experience androgenetic alopecia, the hair follicles shrink, resulting in shorter and thinner hair. Over time, the hair follicles can completely close, so that hair will no longer grow. Dutasteride blocks DHT from shrinking the follicles, and Minoxidil enlarges the hair follicles, allowing thicker, healthier hair to emerge.  

How to Get Oral Dutasteride

Oral Dutasteride is only available by prescription and should be taken under the supervision of a licensed dermatologist. Be sure to follow-up as recommended by your doctor. As with any medication, Dutasteride should be monitored regularly. 

If you have been diagnosed with male or female pattern baldness and are interested in learning more about Dutasteride, Happy Head can help. Not diagnosed for hair loss but feel like you’re losing hair? You can get a FREE consultation with our board-certified dermatologists and get prescribed the treatment you need online by taking our quick questionnaire here and telling us about your hair. We have licensed dermatologists available in every state to answer your questions and determine whether Dutasteride is right for you. We also help make Dutasteride affordable, whether or not you have insurance. Use code GOHAIR for 50 percent off of your first order. 

Resources:

(01) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6388756/

(02) Khandpur, S., & Suman, M. (2014). Dutasteride improves male pattern hair loss in a randomized study in identical twins. Indian journal of dermatology, 59(6), 630-633. doi: 10.4103/0019-5154.143571

(03) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5023004/#:~:text=Sexual%20adverse%20effects%2C%20such%20as,the%20symptoms%20improve%20over%20time.

 

Dealing with Hair Loss? Get These Hormones Under Control.

Here’s a fun fact: hormonal imbalances are the leading cause of hair loss.  At least 50 percent of men are affected by the age of 50. (01)  Ladies, this is true for you too.  Those chemicals that send messages to your organs, skin, muscles, and other tissues are pretty powerful.  They rule your emotions, your weight, your sleep patterns, and, yes, your hair.  If your hairline is receding, or you’re starting to see bald patches on the crown of your head, it may be a sign that you need to get those hormones under control.  Not sure how?  Here are some tips and tricks to help.  

Hormonal Hair Loss Triggers

Before we get into the nitty-gritty, let’s talk about the different types of hormonal hair loss.  Not all hair loss due to hormonal imbalances is the same.  Some hair loss is short-term. Once balance is restored, your hair will grow back.  Other types are a bit more challenging to manage.  In this case, medication can help stop your hair loss and jump-start the growth process.  Fortunately, great progress has been made researching and developing medications designed to treat hair loss due to hormonal imbalances.  Many effective oral and topical options are now available.  So, what hormones cause temporary hair loss, and which create more long-term issues?

Testosterone

We’ll start with testosterone.  Testosterone is the hormone that stimulates the development of male sexual characteristics.  Testosterone affects men’s sex drive and sperm production.  It also plays a role in bone and muscle mass, fat storage, blood cell production, and mood.  Women also produce testosterone, but in much smaller amounts.  

Typically, about ten percent of testosterone in men and women converts to an androgen called dihydrotestosterone (DHT) due to an enzyme called 5-alpha reductase (5-AR).  Once DHT flows through your bloodstream, DHT attaches to the receptors on your hair follicles.  The hair follicles then shrink, making your hair thin and eventually fall out, causing what’s known as male or female pattern hair loss.  

Solution:  Successfully treating male or female pattern hair loss often takes a multi-faceted approach.  Enlarging the hair follicles while blocking the testosterone from converting to DHT is usually the best strategy.  It can, however, take some trial to determine which medications and strengths are most effective for each person.  Minoxidil is often used to open the follicles.  Commonly used DHT blockers include Finasteride, Dutasteride, and Spironolactone.  All of these medications are available in oral or topical formulas.  Many people prefer topicals since they eliminate the risk of systemic side effects.  

Cortisol 

Who isn’t stressed out these days?  Pressure at work, rising costs, and keeping peace at home can be a lot to handle.  When you get stressed out, your body generates extra cortisol.  Cortisol is produced and released in your adrenal glands which are located on top of your kidneys.  Its job as a steroid hormone is to tell your body, ”Hey, you need to chill out!” When your cortisol level gets high, it can reduce the synthesis and speed up the breakdown of hyaluronic acid and proteoglycans in your scalp.  The increase interrupts your hair’s growth cycle, which can lead to hair loss.

Solution:  Breathe.  Hair loss due to stress is usually temporary.  Your hair will grow back on its own once the stressors are gone.  Head outside for a walk, sign-up for a yoga class, or download a meditation app to listen to before bed.  If the usual tricks for restoring calm in your life don’t work, seeking help from a counselor or therapist may be the way to go.  

Triiodothyronine (T3) & Thyroxine (T4)

T3 and T4 are hormones produced in the thyroid gland.  They control how your body uses energy and help regulate many functions from your metabolism to brain development.  T3 and T4 are the markers typically used to help diagnose thyroid disorders.  Too high or too low can be signs of hyper or hypothyroidism.  Both hyperthyroidism and hypothyroidism can lead to hair loss with specific patterns.  People who lose their hair due to thyroid issues usually see thinning over the entire scalp.  

Solution:  Treating the thyroid disorder usually leads to regrowth over several months.  If you think your hair loss may be thyroid related, you’ll need an appointment with an endocrinologist.  Once your thyroid is treated, your hair will slowly grow back.   

Estrogen and Progesterone 

Decreases in estrogen and progesterone levels have been proven to affect women’s hair growth cycles. (02)  That’s why women tend to see their hair thinning or shedding after childbirth or during menopause.  During menopause, a decrease in these hormones also causes an increase in androgens that produce DHT.  DHT conversion happens for women as it does for men, resulting in female pattern hair loss.  Hair lost after childbirth usually resolves itself and grows back over time.  Hair loss due to menopause requires treatment.

Solution:  If you’ve recently had a baby or are nearing menopause age, visit your dermatologist for a consultation and diagnosis.  Postpartum hair loss and female pattern baldness can usually be diagnosed through a visual exam.  There are very specific patterns of hair loss.  You don’t want to assume that your hair loss is hormone-related, just in case another cause requires different treatment.   

How to Treat Hormonal Hair Loss

If your hair loss is due to hormones, treatment options will be based on your condition.  In some cases, your hair will grow back on its own.  Other cases will require treatment.  Here’s an idea of the different types available: 

Minoxidil

Minoxidil, a popular hair loss medication, is sold over the counter and in stronger doses by prescription.  It helps enlarge your hair follicles and allows healthy hair to grow.  It’s best to have a board-certified dermatologist monitor your Minoxidil use.  The reason why is because the medication must be continued once you start using it.  If you discontinue Minoxidil, the hair you grow while using the medication can fall out.  

DHT Blockers

When male or female pattern hair loss is an issue, preventing testosterone from converting to DHT is one of the most effective ways to stop thinning and shedding.  A few different types are available, including Finasteride, Dutasteride, and Spironolactone for women.  Prescription DHT blockers are available in pill or topical formulas.  Each have pros and cons, so it’s important to work with your dermatologist to determine which medication and formula is best for you.  

Supplements

Supplements alone won’t regrow your hair, but they can help treat the root cause of your hair loss.  Iron and vitamin D deficiencies are common among people with hair loss due to hormonal imbalances.  Collagen, probiotics, and other supplements can also help strengthen your hair and scalp.

Thickening Shampoo & Conditioner

The right shampoo and conditioner can help make your hair thicker, shinier, and healthier.  Look for products infused with collagen, saw palmetto, keratin, biotin, and other ingredients that have been proven to support hair growth.

 

Whether you’re 15, 50, or 70, dealing with hormone imbalances can be a nuisance.  However, thanks to research and technology, you have more reliable and accessible options than ever to deal with associated hair loss.  You don’t even have to leave your sofa.  Simply answer a short hair loss questionnaire and our licensed dermatologist will review your case.  If you are a candidate for hormone-induced hair loss, we can make recommendations and deliver customized prescription medications directly to you.  Want to learn more?  Get in touch with us for an evaluation and personalized treatment plan.  

 

Resources:

(01) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5817427/

(02) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7432488/

 

Side Effects of Topical Finasteride: Review of Current Medical Literature

Topical Finasteride is a medication used off-label to treat hair loss. So what are the side effects of using topical Finasteride and how do you know if you'll experience those side effects? It's good to note that not everyone will experience this, so talk to your dermatologist to see what they recommend for you.

Oral Finasteride, also known as Propecia, is an oral medication that has been prescribed by physicians for decades for hair loss. It works in the majority of patients by reducing hair loss and stimulating hair growth, however there can be side effects. One of the most concerning side effects are the sexual side effects, which occur only in 1.8% to 3.8% of patients who take it. As a result, many physicians have been switching to topical Finasteride as an alternative. In recent years, there have been many studies on the efficacy and side effects of topical Finasteride. In this article, we will review the clinical trials and scientific data to evaluate the side effect profile of topical Finasteride

In one of the first single-blind, placebo-controlled clinical trials of topical finasteride, Mazarella et al.1 (1997) published a study of 52 subjects ranging from 19 to 28 years of age. The patients were treated with topical finasteride 0.005% vs placebo for 16 months. These were the results:

  • There was a significant reduction in the rate of hair loss after 6 months of treatment.
  • There were no reports of local or systemic side effects in the patients who received topical Finasteride for treatment. 

In another double blind, randomized clinical trial study conducted with 45 male patients, Hajheydari et al.2 (2009), compared oral Finasteride 1mg vs topical Finasteride 1% for a total of 6 months.

  • Authors concluded that “the therapeutic effects of both Finasteride gel and Finasteride tablet/oral were relatively similar to each other.”
  • One person had erythema of the scalp after application of the topical Finasteride. 

In a prospective pilot study conducted in 15 patients for 9 months by Rafi and Katz3 (2011), patients applied a topical solution called NuH Hair, which is a novel topical combination of Finasteride, Dutasteride, and Minoxidil, with the option to add oral Finasteride, Minoxidil and/or Ketoconazole shampoo for 9 months. 

  • Significant growth was demonstrated after 3 months of use of the topical solution.
  • There were no reports of sexual side effects or irritation or redness reported. 

In a randomized clinical study by Tanglertsampan C.4  (2012), 33 male patients ranging between 27 to 49 years old were enrolled to compare the efficacy and safety of a 24 weeks application of Minoxidil 3% lotion versus Minoxidil 3% combined with 0.1% Finasteride lotion.

Caserini et al. conducted two pharmacokinetic studies on topical finasteride. In a randomized clinical study of 23 males, Caserini et al.5 (2014) compared topical Finasteride 0.25% twice daily vs oral Finasteride 1mg once daily for seven days. They measured Dihydrotestosterone (DHT) and Testosterone levels in the serum (systemic DHT levels).

  • Similar reduction in serum DHT was observed by the use of topical 0.25% Finasteride twice daily  (68-75% ) and oral Finasteride 1mg (62-72%).
  • No sexual side effects were observed. 

In another randomized clinical trial, Caserini et al.6 (2015) did another study involving 50 male patients studying DHT in both the serum and the scalp. 

  • This pharmacokinetic study confirmed that topical Finasteride 0.25% (1ml application twice daily) and oral Finasteride 1mg (once daily) both have similar reduction in scalp (47-51%) and serum DHT levels (74-76%). No changes in testosterone were observed.
  • In the portion of the study where patients used 1ml of topical finasteride 0.25% twice daily, there were 2 patients (11%) that had the following side effects. Elevated ALT levels, pollakiuria and testicular pain. 
  • About 37-54% when 0.1ml, 0.2ml, 0.3ml and 0.4ml of topical 0.25% Finasteride was used, showing relatively similar results to 1ml twice a day application of topical 0.25% Finasteride. Serum DHT was reduced by 24% with the use of 0.1ml, 26% with 0.2ml, 44% with 0.3ml and 48% with use of 0.4ml of 0.25% topical Finasteride. This testing suggests that lower dosage of topical Finasteride may lead to lower reduction of serum DHT levels and thus lower sexual side effects (assuming that serum DHT is solely responsible for the sexual side effects).  
  Scalp DHT Serum DHT
Oral FInasteride 1mg 51% 76%
1ml (twice daily) of 0.25% Topical Finasteride 47% 74%
1ml (once daily) of 0.25% Topical Finasteride 71% 76%
0.1ml (once daily) of 0.25% Topical Finasteride  52% 24%
0.2ml (once daily) of 0.25% Topical Finasteride 47% 26%
0.3ml (once daily) of 0.25% Topical Finasteride 37% 44%
0.4ml (once daily) of 0.25% Topical Finasteride 54% 47%

Oral vs Topical Finasteride

In a retrospective assessment and prospective crossover cohort study of 50 male between 20 to 40 years old by Chandrashekar et al.7 (2017), all 50 patients used Minoxidil 5% and oral 1mg Finasteride for 2 years.They then stopped and their treatment differed.

  • Results showed that 80% to 84.4% of these patients maintained good hair density while on the topical combination of Minoxidil 5% + Finasteride 0.1% treatment for 1 year.
  • No sexual side effects were reported. 

The studies8 above demonstrate that topical finasteride has clinically proven, evidence-based, scientific data to show its efficacy in growing hair and that it has a lower side effect profile compared to oral finasteride. Out of the 7 clinical studies reported above, only one study showed one event with sexual side effects (testicular pain). This is 1 out of 268 subjects in all of the studies, which equates to a rate of 0.37%. In contrast, oral finasteride is associated with sexual side effects in 1.8% to 3.8% of patients, which means that in the above 268 subjects, there should have been about 5 to 10 subjects experiencing some form of sexual side effects. However, this was not the case. Only 1 person had sexual side effects as opposed to 5 to 10 individuals. 

Pharmacokinetic studies by Caserini et al. suggest that lower doses of topical finasteride result in lower reduction of serum DHT compared to oral finasteride and thus lower sexual side effects. No study has conclusively shown the reason of how finasteride can cause sexual side effects. Certainly serum DHT is a contributing factor but may not be the only factor. The reason for this conclusion is because there are studies that patients were on high dosage of topical finasteride and still had no sexual side effects. 

In conclusion, the majority of studies on topical finasteride show no to only a few sexual side effects. However, this does not mean that sexual side effects can not happen. It just suggests that risk of sexual side effects are lower due to the fact that the finasteride is not taken orally. Additional larger clinical studies are needed to address the sexual side effects of topical finasteride. 

References:

1. Topical finasteride in the treatment of androgenic alopecia. Preliminary evaluations after a 16-month therapy course. GF Mazzarella, GF Loconsole, GA Cammisa, GM Mastrolonardo & Ga Vena; Pages 189-192 | Received 23 Aug 1996, Accepted 18 Mar 1997, Published online: 12 Jul 2009

2. Comparing the therapeutic effects of finasteride gel and tablet in treatment of the androgenetic alopecia. Hajheydari Z1, Akbari J, Saeedi M, Shokoohi L. .Indian J Dermatol Venereol Leprol. 2009 Jan-Feb;75(1):47-51.

3. Pilot Study of 15 Patients Receiving a New Treatment Regimen for Androgenic Alopecia: The Effects of Atopy on AGA. Rafi and Katz. SRN Dermatol. 2011;2011:241953. doi: 10.5402/2011/241953. Epub 2011 Apr 11.

4. Efficacy and safety of 3% minoxidil versus combined 3% minoxidil / 0.1% finasteride in male pattern hair loss: a randomized, double-blind, comparative study. Tanglertsampan C1. J Med Assoc Thai. 2012 Oct;95(10):1312-6.

5. A novel finasteride 0.25% topical solution for androgenetic alopecia: pharmacokinetics and effects on plasma androgen levels in healthy male volunteers. Caserini M, Radicioni M, Leuratti C, Annoni O, Palmieri R.  Int J Clin Pharmacol Ther. 2014 Oct;52(10):842-9. doi: 10.5414/CP202119.

6. Effects of a novel finasteride 0.25% topical solution on scalp and serum dihydrotestosterone in healthy men with androgenetic alopecia. Caserini M, Radicioni M, Leuratti C, Terragni E, Iorizzo M, Palmieri R. Int J Clin Pharmacol Ther. 2016 Jan;54(1):19-27. doi: 10.5414/CP202467.

7. Topical minoxidil fortified with finasteride: An account of maintenance of hair density after replacing oral finasteride. B. S. Chandrashekar, T. Nandhini, Vani Vasanth, Rashmi Sriram, and Shreya Navale. Indian Dermatol Online J. 2015 Jan-Feb; 6(1): 17–20. Doi: 10.4103/2229-5178.148925

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