Can the temporary reduction in testosterone with Prolistem cause side effects?
This is one of the most common questions we receive.
The answer begins with understanding where testosterone works.
Most of the testosterone in the body circulates in the bloodstream. However, inside the testis, testosterone levels are naturally much higher and play a key role in regulating the environment surrounding the sperm-producing stem cells.
During Phase 1, Prolistem is designed to induce a temporary and controlled reduction in intratesticular testosterone—not complete testosterone suppression. This modest change is intended to help “reset” the signaling environment within the seminiferous tubules, particularly the activity of Sertoli cells, which support sperm development.
Research has shown that carefully reducing intratesticular testosterone for a limited period can stimulate biological pathways involved in spermatogonial stem cell activation and regeneration. This concept has also been explored in experimental studies investigating the recovery of spermatogenesis.
In our clinical experience, this temporary reduction has been well tolerated, and testosterone levels are restored during Phase 2, when the focus shifts to supporting sperm maturation.
At Prolistem, every step of the treatment strategy has a purpose—because improving the testicular environment comes before improving the chances of finding sperm
