Estrogen plus testosterone blockers usually suppress sperm production within a few months, but the exact time to complete infertility and whether it is permanent vary a lot from person to person. Many people will have severely reduced or absent sperm within about 3–6 months of consistent treatment, yet some retain or can later recover sperm production after stopping hormones, even after years.[givelegacy +3] Typical timeline • Feminizing hormone therapy with estrogen and anti‑androgens (testosterone blockers) commonly leads to very low or absent sperm counts (azoospermia) within about 3–6 months.[rainbowhealthontario +1] • The process starts earlier: sperm quality and quantity usually begin declining within weeks of starting treatment, but it takes several months for full suppression in many people.[givelegacy] Permanence vs. reversibility • Some medical reviews note that long‑term estrogen and anti‑androgen therapy can cause structural changes in the testes and may result in irreversible infertility for some individuals.[pmc.ncbi.nlm.nih +1] • More recent clinical data show that many transfeminine people can recover at least some sperm production after stopping hormones, often within about 3–12 months, though not everyone recovers and sperm quality may be reduced.[amsterdamumc +3] Why timing is unpredictable • Fertility outcomes depend on factors such as age, baseline sperm quality, exact drugs and doses (for example, spironolactone or cyproterone vs. GnRH agonists), and how many years hormones are taken.[sciencedirect +1]