Testosterone Replacment Therapy Risks and Side Effects

Testosterone Side Effects in Men

It’s important to know that if you’ve had prostate cancer or breast cancer you are absolutely not a candidate for testosterone therapy.  Testosterone can make either of these cancers grow faster. 

Dangers of Testosterone Therapy

  • Fluid Retention: It is possible, especially within the first few months of treatment, for a man to retain fluid. Studies of healthy older men have shown problems with fluid retention leading to ankle or leg swelling, worsening of high blood pressure or congestive heart failure. It is unclear whether there would be an effect in men who are ill, for example those with congestive heart failure.
  • Liver Toxicity: There have been no reports of liver toxicity from transdermal testosterone replacement. However, oral testosterone replacement can cause significant liver problems. Interestingly, every manufacturer (even those producing transdermal testosterone) mentions the possibility of liver problems. This should be taken into account.
  • Problems with Fertility: Spermatogenesis (the production of sperm) in all men is dependent on production of testosterone by the testes. If testosterone is given from outside, the testes will stop producing their own testosterone. This will shut down sperm production either significantly or completely in nearly all men. This may be a temporary or permanent testosterone side effect. Younger men, who still plan to have a family, must take this into account when considering the effects of testosterone replacement therapy. Some men have "banked" their sperm (for more information on this subject visit www.SpermBankDirectory.com.) Other men have delayed testosterone replacement until they have finished having children. It is important that any man considering a family be very careful in starting testosterone treatment of any kind.
  • Sleep Apnea: Sleep apnea is a condition in which individuals stop breathing for periods of time while sleeping. This can have significant medical effects. There have been reports that increased testosterone levels exacerbate pre-existing sleep apnea. However, a 36-month trial of testosterone therapy in older men reported no effect of treatment on apneic or hypoapneic episodes.
  • Tender Breasts or Enlargement of Breasts: This may occur in some older men who are on testosterone therapy. This may be due to the conversion of testosterone to estrogen. Breast tissue in both men and women is very estrogen sensitive. Sometimes this testosterone side effect can be overcome by decreasing the dosage of the testosterone.
  • Increased Red Blood Cell Concentration (Polycythemia): One of the most important side effects of testosterone replacement therapy can be an increase in the red blood cell mass and hemoglobin levels. This is particularly true of older men. Increased blood cell mass may increase thromboembolic events (heart attacks, strokes or peripheral clotting in the veins). Men who develop increased hematocrit can decrease testosterone replacement or can donate blood to decrease their blood cell mass.
  • Prostate Growth: The growth of the prostate can have a negative effect on men in two ways. First, the prostate may increase in size (benign prostatic hyperplasia or BPH). This may cause problems with urination. Second, it may promote the growth of cancerous prostate cells. It is important to remember that prostate cancer is a common cancer for older men and is the second most common cause of cancer deaths in older men.

Additional Testosterone Therapy Side Effects Information

Decreasing testosterone levels has been a method used to treat diseases related to both the "benign" and the cancerous groups of cells, but it is still unclear whether testosterone therapy for the older man places him at increased risk of developing prostate disease (i.e., whether testosterone replacement therapy makes benign prostatic hyperplasia progress or makes previously unknown prostate, or sub-clinical, cancer spread).

The vast majority of studies following PSA (prostate specific antigen made by both cancer cells - at a higher rate - and benign prostate cells) show that it does not increase significantly with testosterone therapy. All of the short-term studies have shown no negative effects on prostate size, maximum urination flow rates and prostate symptom scores. It appears that testosterone replacement therapy has little short-term effect on the prostate. However, long-term data is as yet not available.


To learn more about testosterone side effects, andropause symptoms and testosterone therapy please call Dr. Werner's office at (646) 380-2700 in NYC, (914) 997-4100 in Westchester, or (203) 831-9900 in Connecticut, or send us an email at info@wernermd.com.