Low testosterone levels can sometimes be the hidden cause behind low energy, muscle loss, increased body fat, and other unwelcome symptoms. The good news is that, while around 40% of men older than 45 are affected by this condition, there are various testosterone replacement therapy (TRT) options available to restore healthy hormone levels.
But while the benefits of TRT are well-known, it's important to be aware that managing hormone levels may bring some side effects. If you’re receiving testosterone therapy, it’s always advisable to stay informed and consult your doctor for expert advice.
Likewise, if you’re considering TRT, and are curious about its effects or potential risks, this guide will explore the treatment, plus common and scarce side effects of testosterone treatment.
What is TRT (Testosterone Replacement Therapy)?
Testosterone Replacement Therapy is a medical treatment designed to address low testosterone levels in the body. True to its name, TRT aims to restore hormone levels that naturally decline with age, as well as due to health conditions like diabetes and obesity, lifestyle choices such as smoking, and medications like painkillers and antifungals.
As the primary ‘male hormone’, testosterone plays many key roles. It helps to maintain muscle mass, supports red blood cell and sperm production, sustains sex drive, and boosts energy levels.
If you suspect that your testosterone levels may be running low, you can use our ADAM questionnaire to determine if your symptoms match the effects commonly observed with low testosterone and associated indicators.
However, a doctor's consultation is always required to provide a definitive low testosterone diagnosis, usually by examining common symptoms and carrying out a thorough evaluation alongside two low testosterone results.
Most Common Side Effects of TRT
TRT can serve as a game changer to restore low testosterone levels. But like any medical treatment, it comes with the risk of side effects.
Patients considering or undergoing treatment can prepare for potential side effects by researching common adverse reactions linked to a chosen TRT method.
We should note that while side effects are possible on treatment, our professional medical team at MANUAL is highly successful at removing or limiting adverse reactions through the most modern treatment protocols.
Infertility
Supplementing testosterone supply may appear to boost fertility, but in reality - TRT can reduce male reproductive capacity. High levels of replacement testosterone prompt the brain to reduce the body’s natural hormone production to help restore hormonal balance.
This androgen suppression also lowers the production of two key hormones - luteinizing hormone (LH) and follicle-stimulating hormone (FSH) - both necessary for sperm production. The combined reductions can cause a temporary stop to testosterone and sperm production, with testicular shrinkage on TRT being a known effect of this change. However, this isn’t always the case for everyone.
Not all patients experience a drop in fertility during TRT, and some are still able to conceive despite treatment. If you are trying to conceive in the next 6 months, then it may be best to wait before starting TRT. However, if your plans for children are in the future, your doctor may recommend a test before starting treatment, along with medication to help maintain your fertility.
At MANUAL, we offer a range of effective treatments to support testicular function during testosterone replacement therapy (TRT), including injectable and oral medication options. It’s worth mentioning that many patients don’t experience a significant drop in testosterone while on TRT, and are still able to conceive naturally during treatment.
Change in Body Shape
During treatment to raise testosterone levels, one of the noticeable side effects of testosterone hormone therapy is a change in body shape. This shape change may appear in distinct ways, depending on factors like body composition, age, hormone levels, and the duration of replacement therapy.
As the primary male hormone, testosterone has muscle-building capacities that significantly impact fat-free mass throughout the body. By stimulating muscle tissue growth, this can increase overall body weight, leading to visible changes in appearance.
Research also suggests that weight gain may result from the effect of TRT on water retention and muscle mass gain.
Water retention is due to a change in the balance of hormones, where excess testosterone may be converted into oestrogen, but this is generally temporary, with most patients returning to normal within a few weeks. In those that feel this is a persistent issue, we have specific anti-oestrogenic medicines that can resolve this.
On the plus side, patients also report a reduction in BMI, waist size, improved glycaemic control and lipid profile, alongside significant increases in muscle mass when receiving testosterone therapy.
Acne
For patients considering TRT to boost testosterone levels, an increase in acne is a common side effect when patients first start treatment.
High levels of external testosterone can cause hormonal fluctuations, stimulating sebaceous (oil-producing) glands to produce more sebum—an oily substance known to clog hair follicles and cause breakouts. Likewise, testosterone’s effects on increasing skin cell turnover can lead to a buildup of dead skin cells, worsening the odds of acne.
But while acne is one of the known side effects of taking TRT, it isn’t always guaranteed—especially if you didn’t experience this skin condition as a teen. Should your replacement journey lead to acne, however, there are several effective treatments available. Usually a dose change solves this side effect, but face washes containing benzoyl peroxide or salicylic acid can reduce and manage the breakout in more severe cases.
Changes in Full Blood Count
Patients with significant heart failure, men with advanced or poorly managed sleep apnea, and smokers are in a select group at risk of more serious TRT side effects. This category of patients are particularly vulnerable to cardiovascular complications, as excess testosterone can trigger increased red blood cell production or polycythaemia.
If testosterone levels are too high, the increased red blood cell production results in thicker, stickier blood which can increase the risk of clots. If not properly managed, this is one of the more serious health risks of testosterone injections. Polycythemia can have severe consequences, placing patients at increased risk of high blood pressure, stroke, and heart attacks.
Other Risks and Downsides of Testosterone Therapy
TRT has many more advantages than disadvantages, but testosterone replacement does have some potential risks if not well managed.
If you think you may require testosterone replacement, consider ordering a blood test to check your total plus free testosterone levels, and consult a doctor for a proper diagnosis.
Once confirmed, you should know that while there are some commonly understood risks associated with testosterone therapy - lesser-known side effects are just as important to consider before starting treatment.
Raised Risks of Sleep Apnea
Research into the connection between TRT and sleep apnea suggests that changes in muscle mass following hormone therapy can cause the muscles in the throat to relax, leading to airway obstruction during sleep.
Additionally, metabolic requirements of higher testosterone levels may also demand more oxygen consumption, reducing oxygen transport to body tissues and worsening severe or uncontrolled sleep apnea.
Anyone living with untreated sleep apnea will need to discuss the risks of treatment carefully and will likely require treatment before starting TRT.
Gynecomastia
Enlarged breasts, also known as gynecomastia, are some of the less common, but notable risks of testosterone supplementation.
This condition makes up notable long-term side effects of TRT use, and is the result of hormonal imbalances, particularly involving testosterone and oestrogen levels that occur through the treatment process.
Stimulating Growth of the Prostate
Historically, there were concerns about the safety of testosterone and the prostate gland. The belief was that higher levels of testosterone increased the risk of developing prostate cancer, causing worry about the safety of testosterone replacement therapy.
However, research now shows that additional testosterone does not increase the risk of prostate cancer. In fact, very low levels of testosterone are associated with a higher risk of prostate cancer.
TRT Medication Side Effects
There are different ways to administer testosterone replacement therapy to align with your specific needs or the form prescribed by a doctor.
Reaction to Testosterone Injection
For instance, injections or pellets are ideal for patients who prefer less frequent doses, and want long-lasting effects. Others who prefer daily administration may find gels, creams, or patches as suitable alternatives instead. While effective, each form comes with its unique set of challenges.
Intramuscular (IM) injections are among the most popular methods for testosterone replacement therapy (TRT). While they are effective for many, potential side effects can occur. For instance, formulations like testosterone undecanoate (Aveed) may cause mild reactions, such as temporary pain or swelling at the injection site.
In rare cases, more serious reactions such as breathing difficulties or allergic responses, may occur, though these are uncommon. Other possible side effects like joint or back pain, nausea, or prolonged erections, should be monitored closely. If any unusual symptoms arise, it's important to contact your healthcare provider promptly to ensure the best care.
TRT Cream & Gel Side Effects
TRT creams and gels can cause side effects such as skin irritation, redness, or rash at the application site. Other potential issues include increased acne, oily skin, and the risk of transferring the hormone to others through skin contact. Users may also experience mood changes, fluid retention, or changes in libido.
Risks of Testosterone Supplementation
Testosterone supplementation carries risks, including acne, fluid retention, and mood swings. It may increase the risk of sleep apnea, cardiovascular issues, and enlarged breast tissue (gynaecomastia). Long-term use can suppress natural testosterone production, leading to reduced sperm count and potential infertility. This is why regular monitoring by one of our experienced doctors on treatment is essential.
Once You Start Testosterone Therapy Can You Stop?
Short answer - yes. However, if you’re invested in maintaining the energy and sexual wellness benefits of the therapy, the more accurate answer is: yes, with the expert guidance of a doctor.
Introducing external testosterone to the body has the unique ability to stop natural production of this hormone. An abrupt end to TRT use can cause a testosterone vacuum in the body, diminishing energy levels and sexual performance. Other side effects may include irritability and even depression or anxiety.
One of the long-term side effects of testosterone replacement therapy is that it can suppress your natural testosterone production, this may lead to a slow return to normal testosterone production levels after stopping replacement therapy.
However, patients on TRT for shorter periods may find that they experience fewer symptoms, and experienced clinics can provide medications to kick start a patient’s natural production. Despite this, recovering natural testosterone production may take several months without medical support, and therefore should be carried out with the supervision of a healthcare provider who can advise on testosterone therapy withdrawal symptoms and an appropriate discontinuation strategy.
Conclusion
Understanding the potential side effects of testosterone replacement therapy (TRT) is crucial for informed decision-making. While TRT can offer significant benefits, it also carries risks such as reduced fertility, body shape changes and acne. Regular monitoring and open communication with our clinical staff can help manage these risks and ensure that therapy remains safe and effective.
¹Male Hypogonadism. Omeed Sizar; Stephen W. Leslie; Janice Schwartz (2024).
²Effects of long-term treatment with testosterone on weight and waist size in 411 hypogonadal men with obesity classes I-III. F. Saad; A. Yassin; G. Doros; A. Haider (2015).
⁴Testosterone use causing erythrocytosis. Andrea Cervi; Amaris K. Balitsky (2017).
⁵Obstructive Sleep Apnea and Testosterone Deficiency. Sung-Dong Kim; Kyu-Sup Cho (2018).
⁶Gynecomastia: Etiology, Diagnosis, and Treatment. Ronald S. Swerdloff; Jason C. M. (2023).
⁷Risks of testosterone replacement therapy in men. E. Charles Osterberg; Aaron M. Bernie; Ranjith Ramasamy (2014).
