Testosterone undecanoate is a male sex hormone. It possible side effects include: a. fluid and electrolyte retention b. impaired glucose tolerance c. increased bone growth and skeletal weight d. headache e. depression f. spermatogenesis suppression causing low sperm count g. persistent erection of penis h. gynaecomastia i. prostatic hyperplasia These side effects are temporary and seen on long term use of testosterone. On stoppage of testosterone undecanoate, these side effects resolve automatically. This does not lead to sterility. As your testosterone level is low so you need supplement of testosterone undecanoate. It works by replacing or supplementing the testosterone that is naturally made in the body. Advice 1. Continue testosterone as suggested by your doctor for 1 month 2. Do not alter dose by yourself unless suggested by your doctor 3. Consume less salt 4. After one month, you again check your serum testosterone level and consult your endocrinologist 5. If you experience any side effect then contact your endocrinologist. You can write here also on Healthcare magic Thanks