Is Testosterone Replacement Therapy Safe?

When properly done, restoring testosterone has been repeatedly shown to be safe. 

There is no scientific evidence that testosterone causes prostate cancer or heart disease. Twenty years ago it was the prevailing theory, but the data haven’t tilted us any closer to that conclusion. To the contrary, there is increasing scientific evidence that testosterone may actually have a protective effect against heart disease, diabetes, obesity, and Alzheimer's dementia. 

However, if you already have prostate cancer, there is a possibility that restoring your testosterone levels may accelerate the cancer's growth and is, therefore, inadvisable.