Medically reviewed by Jill Johnson, FNP
Written by Our Editorial Team
Last updated 9/2/2022
As men age, testosterone can become a scarce commodity. Age can make just about all of your body’s processes less efficient, which can lead to wrinklier skin, slower healing from injuries and a reduction in your bone density.
It can also potentially contribute to lower production of certain essential hormones, including the male sex hormone testosterone.
For many men, this gradual decline in testosterone production that occurs with age can lead to low testosterone, or “low-T” -- a condition that can affect everything from your bone density and muscle mass to your sex drive and risk of erectile dysfunction.
Low testosterone is a treatable condition, and one of the most common treatment options is the use of injectable testosterone to bring your serum testosterone levels back up to normal. This is often referred to as testosterone replacement therapy, or TRT.
Testosterone replacement therapy can deliver real benefits, but it can also accelerate the effects of male pattern baldness.
Below, we’ve discussed why pattern hair loss can occur in men, as well as the indirect role that testosterone can play in the process of developing a receding hairline, bald patch at your crown or other common signs of balding.
We’ve also explained your options for maintaining your hair as you grow older, whether you use testosterone to treat low-T or not.
Before we go into detail about testosterone and your hair, it’s important to briefly clear up what exactly male hair loss is, as well as the key factors that cause it to occur.
As a man, a variety of different factors can cause you to shed hair. These include stress, issues with your diet, infections, illnesses that cause fever and your use of certain types of medication, such as chemotherapy drugs used in cancer treatment.
Even certain hairstyles can cause you to shed hair by pulling on your hair follicles and causing a form of hair loss called traction alopecia.
Most of these issues cause temporary hair shedding, such as telogen effluvium. When a dietary problem or stressful work environment takes a toll on your hair, it’s normally possible to get your hair back once you fix the underlying issue.
The most common type of hair loss in men, however, is male pattern baldness, or androgenetic alopecia.
Unlike most forms of hair loss, which cause temporary shedding, male pattern baldness causes permanent loss of your hair. It usually begins with a receding hairline or bald patch around your crown (the area at the top of your head), before causing a general loss of hair density.
Male pattern baldness is common, and it can potentially affect adult men of all ages. It can vary hugely in severity from mild to extensive, with specialists using tools like the Norwood Scale to assess the extent of this type of hair loss.
So, what causes male pattern baldness, and how is the hormone testosterone involved? Male pattern baldness occurs due to a combination of genetic factors and the effects of an androgen hormone (the clinical name for a male sex hormone) called dihydrotestosterone (DHT).
If you’re genetically prone to pattern hair loss, DHT can attach to receptors located throughout your scalp and cause your hair follicles to gradually become smaller, affecting your hair growth cycle.
This process is referred to as follicular miniaturization, and it can eventually lead to hair follicles that are no longer capable of producing new hairs.
As you’ve likely noticed, the word “dihydrotestosterone” is similar to “testosterone.” This isn’t a coincidence. Your body produces dihydrotestosterone as a byproduct of DHT via the effects of an enzyme called 5 alpha-reductase.
5 alpha-reductase converts a tiny percentage of your testosterone into DHT in certain types of tissue, particularly in your skin, testes and prostate.
During childhood and adolescence, this DHT is important for developing your genitals, prostate and male secondary sex characteristics, such as your voice and body hair.
However, as an adult, DHT doesn’t play a major role in your physiology. However, it can cause a variety of health issues, including prostate enlargement and hair loss.
Many treatments for male pattern hair loss, such as the oral medication finasteride and hair loss shampoos, work by blocking DHT, either at its source or at the follicular level.
We’ve discussed the effects of DHT on your hair in more detail in our full guide to DHT and male hair loss.
If you’ve been diagnosed with low testosterone levels, your healthcare provider may prescribe a form of therapeutic testosterone to help you increase your levels of testosterone so that they fall within the normal range.
Testosterone has important benefits. It’s an anabolic hormone, meaning it helps you to build and maintain skeletal muscle. It also increases red blood cell production, which may lower your risk of developing conditions such as anemia.
Research also suggests that testosterone helps to keep your bones healthy, increase your level of energy, help you to maintain a stable mood and promote a consistent sex drive and healthier erections.
Taking therapeutic testosterone can help to reduce your risk of dealing with the symptoms of low testosterone, which can include:
Erectile dysfunction (ED)
Low sex drive and other forms of sexual dysfunction
Reduced skeletal muscle mass and strength
Insomnia and other sleep difficulties
Reduced body hair growth
Increased body fat
Mental health issues, such as depression
Although testosterone is often given as an injection, it’s also available as a pill, gel, patch and as an implant that’s placed under your skin. Your healthcare provider will suggest the best form of exogenous testosterone treatment for you based on your needs and preferences.
While testosterone itself doesn’t cause hair loss, using testosterone -- whether as an injection or in any other form -- can potentially accelerate the progression of male pattern baldness.
This is because, as we mentioned earlier, a small percentage of the testosterone that circulates in your body is converted into dihydrotestosterone, or DHT, by the enzyme 5 alpha-reductase.
For healthy men, normal testosterone levels range from 300 to 1,000 nanograms per deciliter of blood (ng/dL).
When you increase your testosterone levels by getting a testosterone injection, applying a gel or using a testosterone patch, you provide more testosterone for the 5 alpha-reductase enzyme to use for the conversion of testosterone into DHT.
This increase in DHT levels means that the effects of male pattern baldness, such as slow scalp hair growth or noticeable hair thinning, may happen at a faster pace.
If you have low testosterone, using a form of testosterone therapy to increase your testosterone levels can have real benefits for your health, wellbeing and quality of life.
However, testosterone therapy can also potentially cause side effects, including:
Reduced sperm count
Increased cholesterol levels
Difficulty falling asleep or staying asleep
Elevated risk of heart disease
Worsening of heart failure
Increased risk of blood clots
While testosterone therapy may also cause negative effects if you already have cardiovascular disease, it isn’t clear if it increases your risk of stroke, heart attack or diseases such as prostate cancer.
If you’re considering using testosterone to treat low-T, it’s important to talk about these potential side effects of hormone therapy with your healthcare provider.
Dealing with hair loss can be a frustrating experience, whether it’s something you slowly notice over time or an issue that accelerates after you start using testosterone.
The good news is that male pattern baldness is treatable. Currently, there are two medications that you can use to either slow down, stop or reverse the effects of male pattern baldness and maintain your hair as you get older.
The first of these medications is finasteride, an oral prescription medication. Finasteride works by blocking the effects of the 5 alpha-reductase enzyme. This stops your body from converting testosterone into DHT, shielding your hair follicles from DHT-related damage.
A typical dose of finasteride can reduce your serum DHT levels by around 70 percent, which is enough to combat hair loss for most men.
Clinical studies show that finasteride works well for most men with androgenetic hair loss. For example, a clinical trial from the Journal of the American Academy of Dermatology found that men with pattern hair loss showed improvements after using finasteride over two years.
We offer finasteride online, following a consultation with a licensed healthcare provider who will determine if a prescription is appropriate.
The second of these medications is minoxidil, a topical treatment that’s available as a solution or foam. Minoxidil doesn’t block DHT, but it does stimulate hair growth by moving your hair follicles into the anagen, or growth, phase of the hair growth cycle.
It also increases blood flow to your scalp, which may help your blood vessels supply nutrients to your hair follicles.
Like finasteride, minoxidil is supported by countless studies showing major improvements in hair growth, including some that suggest it’s especially effective at treating hair loss when it’s used in combination with finasteride.
For example, one study published in the journal Dermatologic Therapy found that more than 94 percent of men with pattern hair loss showed improvements after using finasteride and minoxidil over a period of 12 months.
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In addition to evidence-based medications such as finasteride and minoxidil, other products and healthy habits can help you to keep a full head of hair as you age, even if you take testosterone to treat low-T.
These include vitamins and minerals for healthier hair, such as vitamins B12, C, D12 and B7, or biotin. Our Biotin Gummy Vitamins contain a mix of vitamins and nutrients to support hair growth and strong, resilient skin and nails.
Good habits for hair growth include using a hair loss prevention shampoo, quitting smoking and protecting your hair from the sun.
Our guide to lifestyle changes for improved hair growth goes into more detail about these steps and others that you can take for optimal hair health and a reduced risk of hair issues.
If you have clinically low testosterone, your healthcare provider may suggest using testosterone injections, pills, gels or patches to bring your levels up to the normal range.
Testosterone itself doesn’t directly cause hair loss. However, increasing your testosterone levels can also increase your levels of DHT, causing damage to your hair follicles and speeding up the effects of male pattern baldness.
If you’re concerned about hair loss, you can protect yourself by using hair loss medications such as finasteride and minoxidil.
You can also learn more about your options in our full guide to the most effective treatments for thinning hair.