Short-Course Testosterone Therapy Does NOT Improve Natural Testosterone Production
No, a short course of testosterone therapy will not improve natural testosterone production after stopping injections—in fact, exogenous testosterone suppresses the body's own testosterone production through negative feedback on the hypothalamus and pituitary gland, and recovery can be prolonged. 1
Mechanism of Suppression
Exogenous testosterone administration provides negative feedback to the hypothalamus and pituitary gland, resulting in inhibition of gonadotropin (LH and FSH) secretion. 1
During exogenous testosterone administration, endogenous testosterone release is inhibited through feedback inhibition of pituitary luteinizing hormone (LH), and at large doses, spermatogenesis may also be suppressed through feedback inhibition of pituitary follicle-stimulating hormone (FSH). 2
This suppression inhibits intratesticular testosterone production and suppresses spermatogenesis, potentially causing oligospermia or azoospermia depending on the degree of testosterone-induced suppression. 1
Recovery Timeline After Stopping Testosterone
Recovery of natural testosterone production is slow and unpredictable, not rapid or enhanced:
Although recovery of sperm to the ejaculate occurs in most azoospermic males after cessation of testosterone therapy, the time course of recovery may be prolonged and can be months or rarely years. 1
After stopping 2 years of injectable testosterone undecanoate treatment, full reproductive hormone recovery is slow and progressive over 15 months since the last testosterone injection, but may take longer than 12 months to be complete. 3
After short-course LHRH analogue treatment (median 116 days), testosterone levels recovered to normal range in only 35% of men at 12 weeks, 85% at 18 weeks, 89% at 24 weeks, and 96% at 1 year after the last injection. 4
Initially fully suppressed serum LH and FSH recover slowly towards the participant's own pre-treatment baseline over 12 months since the last injection. 3
Clinical Implications for Fertility
For males interested in current or future fertility, clinicians should not prescribe exogenous testosterone therapy. 1
Exogenous testosterone therapy should be avoided in males pursuing or planning to pursue family building in the near future. 1
In those who may want to pursue paternity in the more distant future, testosterone therapy may be offered, but the patient must be counseled about testosterone's inhibitory effects on spermatogenesis and the time course required for resumption of spermatogenesis after cessation. 1
Alternative for Restoring Natural Production
If the goal is to restore natural testosterone production and spermatogenesis (not suppress it), the appropriate treatment is gonadotropin therapy:
The usual first-line drug for treatment of hypogonadotropic hypogonadism for restoration of testosterone production and spermatogenesis is human chorionic gonadotropin (hCG) at 500-2500 IU, 2-3 times weekly, followed by FSH injections when indicated after testosterone levels are normalized on hCG. 1
This approach stimulates the testes directly to produce testosterone rather than suppressing the body's own production. 1
Common Pitfall to Avoid
The critical misconception is that a "short course" of testosterone might somehow "jumpstart" natural production—this is physiologically incorrect. Testosterone therapy works through negative feedback suppression, not stimulation, of the hypothalamic-pituitary-gonadal axis. 1, 2 Any benefit seen after stopping testosterone represents recovery from suppression, not enhancement beyond baseline levels.