Growth hormone does appear to have a modest positive effect on testosterone levels, but the relationship is more nuanced than a simple “yes.” In lab studies, growth hormone directly stimulates the cells in the testes responsible for producing testosterone. In clinical practice, though, the boost is relatively small on its own, and growth hormone is not approved or typically prescribed for the purpose of raising testosterone.
How Growth Hormone Affects Testosterone Production
The cells that produce testosterone in the testes are called Leydig cells, and they have receptors for both growth hormone and its downstream messenger, IGF-1. When growth hormone binds to these receptors, it stimulates testosterone output in a dose-dependent way, meaning more growth hormone leads to more testosterone, up to a point. In this sense, growth hormone acts somewhat like a secondary signal alongside the brain’s primary hormonal command (luteinizing hormone) that tells the testes to produce testosterone.
Beyond the testes, the growth hormone and reproductive hormone systems are intertwined from early development. IGF-1, which the liver produces in response to growth hormone, plays a role in testicular development during fetal life, helps trigger the onset of puberty, and supports the maturation of the reproductive tract into adulthood. So the connection between these two hormonal systems runs deep, not just in adults wondering about optimization, but across the entire lifespan.
What the Clinical Numbers Actually Show
A retrospective study published in the Journal of Multidisciplinary Healthcare tracked men across several treatment groups: testosterone replacement alone, growth hormone alone, the combination, and a control group receiving only diet, exercise, and basic hormonal support. The growth hormone group saw total testosterone rise from 596 to 707 ng/dL, a bump of about 111 points. That increase was not statistically significant for total testosterone. However, free testosterone (the portion your body can actually use) rose from 110 to 156 pg/mL, which was significant.
For comparison, the group receiving testosterone replacement alone jumped from 538 to 927 ng/dL, a far larger and clearly significant increase. The combination group (testosterone plus growth hormone) landed at 814 ng/dL from a baseline of 526. Interestingly, even the control group saw total testosterone climb from 545 to 687 ng/dL with lifestyle changes alone. So while growth hormone nudged testosterone upward, the effect was smaller than what direct testosterone therapy or even structured diet and exercise achieved.
The takeaway: growth hormone can raise free testosterone to a meaningful degree, but it’s not a powerful testosterone booster on its own. If low testosterone is the primary concern, growth hormone is an indirect and relatively weak lever to pull.
The Two Hormones Work Better Together
Where the relationship gets more interesting is in what the two hormones accomplish as a pair. A study in the Journal of Clinical Endocrinology and Metabolism found that testosterone only stimulated protein building (the process behind muscle growth and tissue repair) when growth hormone was also present. Without growth hormone, neither oral nor transdermal testosterone had a measurable effect on protein breakdown or protein loss. Growth hormone alone increased protein turnover but didn’t reduce the body’s protein losses. Only when both hormones were present did the body shift into a genuinely anabolic state, building more protein than it was losing.
This finding matters because many of the outcomes people associate with testosterone, like gaining lean muscle, improving body composition, and recovering from exercise, depend on both hormones working in concert. One without the other is less effective than you might expect.
Exercise Triggers Both Hormones Naturally
Resistance training is the most reliable natural stimulus for both growth hormone and testosterone. Immediately after a hard workout, testosterone levels can nearly triple, jumping from resting levels around 13 nmol/L to roughly 38 nmol/L within about 30 minutes. Growth hormone spikes during the same window, particularly with high-intensity, short-rest-period training. These parallel surges are one reason strength training is so effective at building muscle: it activates both sides of the hormonal equation simultaneously.
The intensity matters. Heavier loads, compound movements, and shorter rest periods between sets produce larger hormonal responses than lighter, more isolated work. Sleep is the other major driver. The largest pulse of growth hormone your body releases each day happens during deep sleep in the first half of the night. Poor sleep blunts both growth hormone and testosterone output.
Risks of Using HGH to Influence Testosterone
Growth hormone therapy is FDA-approved only for diagnosed growth hormone deficiency in adults and a handful of specific conditions in children. It is not approved for general hormone optimization, anti-aging, or as a strategy to raise testosterone. Using it off-label for these purposes carries real risks.
Side effects of HGH therapy in otherwise healthy adults include joint and muscle pain, swelling in the arms and legs, carpal tunnel syndrome, high blood sugar, increased risk of type 2 diabetes, breast tissue enlargement in men, and a potentially higher risk of certain cancers. The blood sugar effects are especially worth noting: growth hormone raises insulin resistance, which can create metabolic problems over time that work against the body composition goals most people are chasing.
There’s also a feedback concern. Injecting synthetic growth hormone suppresses your body’s own production. Once you stop, your natural output may take time to recover, leaving you temporarily worse off than where you started.
What This Means in Practice
If your testosterone is low (below 300 ng/dL by American Urological Association standards), growth hormone is not the right tool to fix it. The effect is too small and the risks too significant compared to direct testosterone therapy or lifestyle interventions. If you have a diagnosed growth hormone deficiency alongside low testosterone, treating both can produce synergistic benefits for body composition, mood, and bone density that neither hormone achieves alone.
For most people, the practical path to supporting both hormones is the unsexy one: consistent resistance training with progressive overload, seven to nine hours of quality sleep, maintaining a healthy body fat percentage, and managing stress. These inputs reliably raise both growth hormone and testosterone through the body’s own feedback systems, without the side effects or legal gray areas of exogenous hormones.