- Testosterone, the primary male sex hormone, is essential from developmental years to adulthood. When men experience low levels of testosterone, it can affect a range of bodily functions, causing sexual, physical, and psychological side effects.
- Low testosterone can be caused by age, lifestyle, and medical factors, but also by environmental toxins.
- Your thyroid plays an important role in testosterone production, and low levels in one can cause an imbalance in the other.
- At Male Excel, we diagnose low testosterone using our finger-prick blood spot test - an effective and self-administered method.
- We offer both daily subcutaneous (SubQ) injections and Lipoderm gel as treatments for low testosterone. These are both effective and convenient forms of TRT, which can work for different types of lifestyles.
- Modern studies confirm that TRT is safe when used properly, acknowledging the many proven benefits it provides.
First published: April 16 2020. Updated: September 4 2025
Why Testosterone Matters More Than You Think
Testosterone is the primary male sex hormone, produced in your testicles and, in smaller amounts, your adrenal glands. While women also produce testosterone in much lower quantities, it plays a fundamental role in male development, beginning in the womb and continuing throughout adulthood. For men, testosterone influences a wide range of bodily functions. It controls reproduction, builds muscle mass and bone density, regulates fat distribution, and can even influence your mood. When testosterone levels are low, whether due to age, lifestyle, or an imbalance of other hormones, it can have significant effects on your sexual, physical, and mental health.
What Does Testosterone Do?
Male Development
Testosterone is an androgen, meaning that it promotes the development of male sex characteristics. Its influence begins in the womb, with the formation of reproductive organs such as your penis, scrotum and testes. During puberty, your testosterone levels surge, and this triggers the onset of secondary sexual characteristics - such as a deepened voice, an increase in muscle mass, and the growth of pubic, body and facial hair. It's also responsible for producing sperm, increasing sex drive, and is often linked to more aggressive, risk-taking behavior. These changes mark the transitional period from boyhood to manhood, in which your testosterone production reaches its peak.
Sex, Energy, Muscle and Mood
In adulthood, optimal levels of testosterone help to maintain these sexual functions - supporting your libido and reproductive health. It plays a key role in sustaining erectile function and can even enhance the overall sensation and satisfaction of sex. It's vital for male fertility, as it stimulates sperm production within the testes, maintaining its quality and motility.
But the importance of testosterone goes far beyond sexual health. It's also responsible for increasing your levels of erythropoietin (EPO), a hormone that stimulates your bone marrow to produce red blood cells. By boosting EPO production, testosterone helps to ensure that your red blood cells carry enough oxygen to your muscles and organs, allowing them to function efficiently. When this oxygen delivery is optimal, your cells are able to produce energy more efficiently, improving your stamina and reducing fatigue.
By binding to androgen receptors in your muscle tissue, testosterone activates muscle protein synthesis (MPS). This is the process by which your body builds and repairs muscle tissue, and it's essential for your overall muscle health. MPS allows you to maintain strength, as well as supporting recovery after exercise, making it crucial to your overall muscle health.
When testosterone binds to androgen receptors in your cell nucleus, it interacts with your DNA, influencing gene expression. This process can influence the production of key neurotransmitters, such as dopamine and serotonin, which regulate your mood. When testosterone increases dopamine, it can make you feel more driven and motivated, boosting your positivity and mental sharpness. Higher serotonin levels can reduce anxiety, improve your sleep cycle, and contribute to an overall sense of emotional control.
What Causes Low Testosterone?
Age-Related Decline
As men age, testosterone levels naturally decline, a process sometimes called andropause or late-onset hypogonadism. Unlike the sudden hormonal changes of female menopause, this shift is far more gradual. Testosterone production usually begins to decrease around the age of 30, and then continues to decrease by around 1% each year. Almost 40% of men over 45, and over 50% of men over 75, experience clinically low testosterone.
This natural decline is influenced by several interconnected changes to your hormonal system.
Aging can also reduce the secretion of gonadotropin-releasing hormone (GnRH), produced in the hypothalamus region of your brain. This hormone stimulates your pituitary gland to release LH and FSH, so when the secretion of your GnRH slows down, it can lead to low testosterone. This knock-on effect disrupts the hypothalamic-pituitary-testicular (HPT) axis, a hormonal feedback system that regulates male reproductive function. After testosterone is produced, it loops back to the hypothalamus and pituitary gland, providing feedback to regulate the release of GnRH, LH and FSH. When this loop is disconnected, it interrupts your hormonal balance.
Lifestyle and Medical Conditions
There are several lifestyle and medical factors that contribute to low testosterone levels. Being overweight or obese can increase levels of aromatase, an enzyme that converts testosterone into estrogen, effectively reducing the amount of testosterone circulating your body. Obesity is also associated with insulin resistance, which can decrease the production of sex hormone-binding globulin (SHBG), a protein that binds to testosterone and transports it through the bloodstream. Men who live a sedentary lifestyle, engaging in little or no physical activity, often have reduced testosterone levels. Lack of exercise leads to decreased muscle mass and poor circulation, reducing MPS and limiting oxygen delivery to Leydig cells. This restricts two key components of healthy testosterone production.
Excessive alcohol consumption and smoking can also contribute to lower testosterone levels. Alcohol can damage your Leydig cells, disrupting the HPT axis, and elevate your levels of cortisol - a stress hormone that suppresses testosterone. Long-term smoking can reduce blood flow to the testes, damaging your Leydig cells by increasing oxidative stress. This is a condition that occurs when there are too many unstable molecules in your body, and not enough antioxidants to neutralize them. Smoking can also reduce the secretion of LH from the pituitary gland, lowering testosterone production further.
In order to maintain healthy levels of testosterone production, it is essential to have adequate sleep. This is because most testosterone release occurs while you are sleeping - in particular, during REM. When your cycle is disrupted due to sleep deprivation, or disorders such as sleep apnea, it can disrupt your testosterone levels as a result. Well-functioning levels of testosterone are one of the many health benefits of getting quality sleep, and most men should aim for 7 to 9 hours a night.
Even your mental health can contribute to low testosterone. Men who suffer from chronic stress have higher cortisol levels, which can prevent testosterone from being produced. When cortisol is elevated, it competes with testosterone due to the similar pathways and resources they share. Both hormones rely on similar precursor molecules such as cholesterol, and they interact with overlapping parts of the HPT axis. When stress levels are high, the body prioritizes cortisol, suppressing the signals needed for testosterone production. This creates an imbalance in your hormonal control system, which can ultimately worsen your mental well-being. Stress lowers testosterone levels, resulting in symptoms such as fatigue, low mood and poor motivation, which make it harder to cope with stress - a cyclical effect.
Environmental and Chemical Exposure
Exposure to certain chemicals and environmental toxins can also have a negative impact on your testosterone production. Endocrine-disrupting chemicals (EDCs) such as phthalates, bisphenol A (BPA), and some pesticides can all interfere with the HPT axis.
Because some EDCs have a similar chemical structure to your natural hormones, such as testosterone and estrogen, receptors in your body can mistake them for the real thing. When these chemicals bind to those receptors, they can either mimic hormonal action - causing inappropriate biological responses - or block your actual hormones from functioning correctly.
The Thyroid-Testosterone Connection
It's common for men with low testosterone to also suffer from an underactive thyroid. This is because thyroid hormones help to regulate SHBG, the protein that transports testosterone, estrogen and dihydrotestosterone (DHT) around your body. It is therefore essential to the distribution of testosterone, and imbalances in one can significantly impact the other. An underactive thyroid can decrease the production of SHBG, disrupting the balance between bound testosterone (attached to proteins in your body, and therefore inactive) and free testosterone (readily available for your body to use). As a result of this, even if your total testosterone levels appear normal on a blood test, hypothyroidism can reduce the amount of usable testosterone circulating in the body.
At Male Excel, we always monitor thyroid function alongside testosterone levels, in order to gain a wider and more accurate understanding of your hormone health.
Symptoms of Low Testosterone
Insufficient levels of testosterone can have a range of effects on your physical, mental and sexual health. Here are some examples of symptoms in men:
- Low energy and fatigue
- Erectile dysfunction
- Difficulty concentrating, memory lapses, and slower mental processing
- Weight gain
- Depression and irritability
- Reduced muscle mass and strength
- Reduced facial and body hair growth
- Difficulty falling asleep or staying asleep
- Infertility
- Gynecomastia (increased breast tissue)
How Low Testosterone Is Diagnosed
Male Excel's At-Home Finger Prick Test
Our hormone test can be completed in the comfort of your own home, with no needles and no office visits. Rather than a blood draw, we use blood spot testing, accurately measuring your hormone levels through a small finger prick. This method offers a total picture of hormone imbalance, and enables you to compare future tests to your baseline - so you can see measurable progress in your optimization journey.
How Testosterone Replacement Therapy Works
Daily Subcutaneous Testosterone Injections
Daily subcutaneous (SubQ) injections are an effective method of TRT, delivering testosterone in controlled and natural doses. Using a small 31-gauge needle, much like the insulin syringes commonly used to treat diabetes, medication is inserted just beneath the skin into fatty tissue, typically in your thigh. Unlike weekly intramuscular (IM) injections, in which a large needle is inserted deeply into muscle tissue, SubQ injections can be self-administered and are generally painless.
By injecting smaller doses of testosterone on a daily basis, you can avoid the spikes and crashes that often occur with weekly injections. This helps to keep your testosterone levels balanced, regulates your estrogen conversion, and reduces the risk of side effects linked to fluctuating hormone levels.
Testosterone Lipoderm Gel
Lipoderm gel is an easy and effective way to boost testosterone levels. It's a topical treatment and is best administered on the testicles, where the skin is very thin, allowing for optimum absorption. However, it is important to note that certain precautions are vital, to ensure the prevention of cross-contamination.
Testosterone gels and creams can cause side effects in women, children, and even pets who accidentally come into contact with it. In children especially, these side effects can be extremely serious: including early-onset puberty, aggressiveness, enlarged genitals, excessive hair growth, and acne. In women, contact is particularly dangerous during pregnancy, due to the risk of causing birth defects.
By following the correct precautions, you can avoid any risks:
- Do not allow the treated area to come into contact with other people
- Cover the treated area 20 minutes after application
- Do not allow others to touch clothes or bedding that have come into contact with testosterone gel
- Do not stroke animals after applying testosterone gel
- Wash hands thoroughly after each application
Injection vs Gel - How Should I Choose?
There is no one-size-fits-all answer to choosing between testosterone injections and gel. It usually depends on your personal lifestyle, and how your body responds. Like with any medication, there can be side effects - but with the bioidentical hormones we offer, these are normally pretty minimal. Here are a few comparisons to help navigate your TRT journey:
| Daily SubQ Injections | Testosterone Lipoderm Gel/Cream | |
| Administration | Can be administered yourself, but self-injection may be less convenient | Simple and quick to apply |
| Cholesterol | Lowers bad cholesterol | Lower bad cholesterol more effectively |
| Pain | Generally painless application | Painless application |
| Consistency | Daily injections prevent hormone spikes and crashes | Daily application keeps levels steady, but absorption varies |
| Absorption | More predictable absorption and effect | Convenient, but can vary from individual to individual |
| Side effects | May convert testosterone to estradiol in overweight men | Lower risk of estrogen conversion in overweight men |
| Lifestyle impact | Fewer concerns about transference | Must avoid skin contact with others for 4 hours, and wash hands thoroughly |
| Testing | Requires monitoring, but generally gives more stable results | Requires regular blood tests to check that absorption is effective |
Is TRT Safe and Effective?
Modern Evidence and Safety Profile
When properly monitored and administered, TRT is considered both safe and effective for men. While previous, outdated concerns linked TRT to cancer or cardiovascular disease, modern studies have proven that this is simply not true. In fact, it is actually low testosterone itself that can be associated with a higher cardiovascular risk.
Proven benefits of TRT include:
- Improved sexual function and libido
- Enhanced mood and emotional wellbeing
- Healthier body composition - more muscle, less fat
- Increased bone density
- Improved general quality of life
Long-Term Health Impact
The benefits of TRT are long-lasting, and with the right medical supervision, many men experience sustained improvements to their physical, mental and sexual health. By supporting a healthy bone mineral density, TRT helps to reduce the risk of conditions such as osteoporosis - the weakening of your bones with age. It also improves your lean muscle mass and reduces visceral fat, which helps to protect against metabolic disorders such as type 2 diabetes.
Ongoing TRT treatment can help to relieve symptoms of depression and fatigue, sharpening your cognitive function and improving your overall mood. It can restore your drive, give you a sense of self-assurance, and keep your emotions regulated. Men on TRT also experience a consistent sexual confidence over the years - with a balanced libido and healthy erectile function.
Through personalized treatments and regular monitoring, we make your safety our priority.
Get TRT Online
Optimize Your Hormones
