Unexpected effects of testosterone therapy you should know
Dr. Susan Carter, MD: Endocrinologist & Longevity Expert
Aug 23, 2025 · 16 min read
Testosterone therapy can cause “unexpected” side effects beyond libido and muscle gains, including bone marrow driven rises in hemoglobin/hematocrit that can reach erythrocytosis when hematocrit exceeds ~54%, along with water retention, acne, mood changes, and reduced fertility. Here’s what to monitor, why these effects happen, and how to manage them safely with your clinician. “Testosterone ...