Most side effects of testosterone replacement therapy occur when the dose is higher than a man actually needs. The common ones include gynecomastia, testicular shrinkage and a rise in red blood cell count. All three are monitored through regular blood work, and all three are manageable when treatment is supervised properly.
Why dosing is the main factor
The side effects men worry about are largely dose-related. Giving more testosterone than the body needs is what produces them, which is why careful dosing matters more than almost anything else in this treatment.
The aim is an optimal clinical result, not the highest number on a lab report. More is not better.
Will TRT cause gynecomastia?
Gynecomastia — enlarged breast tissue in men — happens because some testosterone converts to estrogen in the body. If levels run too high, that conversion increases.
This is one of the reasons we measure estrogen alongside testosterone rather than testosterone alone, and why we monitor labs and side effects closely throughout treatment. In our experience it is extremely rare for men in our care to develop gynecomastia.
Does testosterone cause testicular shrinkage?
It can. When the body receives testosterone from outside, it reduces its own production, and the testes can reduce in size as a result.
This typically happens when patients are not prescribed HCG. Our treatment protocols use medication to support your natural production and reduce the likelihood of testicular shrinkage. If a patient does notice this during treatment, they should contact the office so the plan can be reviewed.
Men for whom this is a particular concern — especially those planning a family — often choose enclomiphene instead, which stimulates the body’s own production rather than replacing it.
Does TRT affect the prostate?
Testosterone does not cause prostate cancer. A pre-existing cancer could be made worse by it, however, which is why a baseline PSA test is carried out before treatment begins.
PSA is then repeated every six months during therapy, alongside a series of urinary questions. This is standard monitoring and it is not optional.
Red blood cell count
Testosterone can increase the production of red blood cells. A modest rise is expected; a larger one needs attention, because thicker blood carries its own risks.
This is picked up on routine blood work, which is one of the practical reasons monitoring continues for as long as treatment does.
Do the injections hurt?
It depends on the patient. The shots are intramuscular and, for most patients, are not painful.
Injections are not the only option either — testosterone can also be given as a topical cream or gel, or as a long-acting medication placed just under the skin.
What happens if I stop treatment?
Nothing adverse happens if you cease therapy, but your testosterone returns to where it was before you began — or lower. That means your original symptoms return.
If you do stop, you can resume later to restore your levels. It is not a one-way decision.
How side effects are kept manageable
The pattern across all of the above is the same: appropriate dosing, regular blood work, and a physician who adjusts the plan when the numbers move.
Once your optimal levels are established, lab work continues every six months. Any provider offering testosterone therapy without that monitoring is not managing the treatment properly, whatever the price.
Your physician will explain the potential side effects relevant to you at your examination, before you begin.
Call 1-800-530-7746 or book a free consultation.
Related reading
For independent information on this topic, see FDA information on testosterone products.
Medically reviewed by John Webb, MD, MBA. Dr. Webb completed a men’s health (Andrology) clinical research fellowship at Harvard Medical School and has nearly 20 years of experience in progressive healthcare leadership.
This article is general information and is not medical advice or a substitute for consultation, diagnosis or treatment by a licensed healthcare professional.