Can I Take HGH and Testosterone Together?

Combining human growth hormone (HGH) and testosterone is medically possible and has been studied in clinical trials spanning several decades. Researchers have found that the two hormones can produce additive, and in some cases synergistic, effects on lean body mass, fat loss, and protein metabolism. But whether you personally should take them together depends entirely on your clinical situation, because the combination also amplifies certain risks and sits in a complicated legal gray zone.

What Clinical Trials Actually Show

The most consistent finding across studies of combined HGH and testosterone is a shift in body composition: more lean mass, less fat. In a study of healthy older men, lean body mass increased across all treatment groups receiving various dose combinations, with gains ranging from about 1 to 3 kilograms, while fat mass dropped by roughly 0.4 to 2.3 kilograms depending on dose.¹ A separate randomized trial found that fat-free mass increased significantly only under combined GH and testosterone exposure, not under either hormone alone.²

Strength improvements, by contrast, are less impressive and more inconsistent than the body composition changes might lead you to expect. In one trial, midthigh muscle area and aerobic capacity improved with the combination, but only one out of six strength measures reached significance.³ A larger randomized trial in men and women found that lean body mass gains were strongly related to improvements in both strength and aerobic capacity, yet the strength gains themselves barely reached significance even in the combination group.⁴ So while you gain measurable muscle tissue, that tissue does not always translate into proportionally greater force output in the short term.

Why the Two Hormones Work Better Together

Testosterone and HGH operate through overlapping but distinct pathways. Testosterone binds to androgen receptors in muscle, which stimulates the local production of IGF-1, a growth factor closely linked to muscle protein building. It also appears to independently activate cellular signaling pathways involved in muscle growth.⁵ Growth hormone, meanwhile, raises circulating IGF-1 levels through the liver and promotes fat breakdown.

The key insight from clinical research is that testosterone boosts the IGF-1 rise triggered by GH, but does not raise IGF-1 on its own when GH is absent. In men with pituitary hormone deficiencies, GH and testosterone had independent and additive effects on protein metabolism, fat burning, and resting energy expenditure.⁶ Further research pinpointed the liver as the primary site where this hormonal interaction plays out: testosterone stimulates protein building by reducing protein breakdown and oxidation, but only when GH is also present.⁷ This liver-centered synergy helps explain why the combination outperforms either hormone individually for body composition.

Side Effects and Safety Signals

Adding two hormones together does not simply double the benefits; it also broadens the side-effect profile. In a large JAMA trial, edema was significantly more common in women taking GH-based regimens, carpal tunnel symptoms were more common in men on the combination (about a third versus none in placebo), and joint pain was more common in men receiving GH alone. Most strikingly, diabetes or glucose intolerance occurred in 18 GH-treated men compared with 7 who were not receiving GH.⁴

A retrospective study following over 500 patients for at least a year found the overall incidence of adverse clinical outcomes, including prostate disease, diabetes, cardiovascular disease, and cancer, was about 1.3%. The combination of testosterone and GH without statins lowered total cholesterol and LDL, which sounds favorable. However, glycated hemoglobin rose slightly (still within normal range) in patients receiving GH alone or with testosterone.⁸

Fluid retention deserves its own mention. GH treatment increases extracellular water, and testosterone amplifies this effect. When the two are given together, the fluid shift is more pronounced than with either alone.⁹ This matters because some of the early “weight gain” you see on the scale reflects water, not muscle tissue. It also contributes to side effects like swelling, carpal tunnel syndrome, and joint stiffness.

Self-administration at supraphysiological doses, which is what happens in many bodybuilding contexts, introduces additional risks. A study of bodybuilders who used testosterone, anabolic steroids, and HGH together found significant decreases in HDL cholesterol and apolipoprotein A-1, both protective against heart disease.¹⁰ High-dose abuse and therapeutic dosing are entirely different animals, and most safety data from clinical trials do not apply to the doses commonly used in performance-enhancement settings.

Fertility Is a Major Concern

If you are a man considering this combination and might want children in the future, testosterone’s effect on sperm production is the single most important risk to understand. Exogenous testosterone suppresses the hormonal signals that drive sperm production, typically pushing sperm counts below one million per milliliter within about three and a half months.¹¹ After stopping testosterone, recovery data suggest roughly two-thirds of men recover normal sperm counts within six months, and about 90% within a year, though longer use, higher doses, and older age all slow the process.¹¹

The less reassuring part: an estimated 10 to 20% of men may never fully recover normal hormonal axis function or sperm production after discontinuing exogenous testosterone, particularly those with a history of long-term or high-dose use.¹² HGH alone does not suppress sperm production the way testosterone does, but the combined protocol still carries this fertility risk because of the testosterone component. Some clinicians prescribe medications alongside testosterone to preserve fertility, but this adds complexity and is not always effective.

Where Combined Therapy Has Shown Clinical Promise

Most of the research on this combination has been conducted in specific medical populations, not in healthy adults looking for a performance edge. Understanding where it has been studied helps clarify who might genuinely benefit.

In heart failure patients with multiple hormone deficiencies, one year of combined GH and testosterone replacement improved peak oxygen consumption by over 50% from baseline and grip strength by about 26%, with no major adverse cardiovascular events reported during follow-up.¹³ These are patients whose bodies are not producing adequate amounts of either hormone, so replacement corrects a genuine deficit rather than pushing levels above normal.

In patients with facioscapulohumeral muscular dystrophy, a 24-week trial of combined testosterone and recombinant HGH found lean body mass improved by about 2.2 kilograms, fat mass decreased by 1.3 kilograms, six-minute walk distance increased by 37 meters, and overall strength increased by 3%. Nineteen of 20 participants completed the study, and the most common adverse event was mild injection site reaction.¹⁴

Burn recovery is another context where anabolic hormones have been explored. A comparison of HGH and the testosterone analogue oxandrolone in severe burn patients found that both agents reduced weight and nitrogen loss and improved wound healing with nearly identical benefits. However, HGH caused significant hyperglycemia and worsened the already elevated metabolic rate, which made oxandrolone the preferred option for many burn clinicians.¹⁵

An animal study on bone density found that combining GH and testosterone in androgen-deficient aged rats produced cortical bone area, bone formation rates, and bone mineral density higher than either treatment alone and even higher than in intact control animals. Interestingly, the two hormones had independent effects rather than a true synergistic interaction on bone, meaning they added to each other but did not multiply each other’s effect.¹⁶ This has not been established as clearly in human trials.

The Prostate Question

Anytime testosterone is prescribed, prostate concerns come up. Adding GH to the mix introduces an additional layer of uncertainty, because GH raises IGF-1 levels, and IGF-1 has been linked to cell growth in the prostate. A comparison of untreated men with acromegaly (a condition of chronic GH excess) to matched healthy controls found that the acromegalic men had significantly larger prostate volumes and more structural changes. When their GH and IGF-1 levels were brought down to normal with medication, prostate volume decreased.¹⁷

In the retrospective safety study mentioned earlier, the overall incidence of prostate disease among patients on combined therapy remained low within the roughly 1.3% overall adverse outcome rate.⁸ Still, the evidence base is not large or long enough for anyone to say the combination is definitively safe for the prostate over periods of many years. Men with a personal or family history of prostate cancer are typically advised to avoid testosterone therapy altogether, and adding GH to that picture only increases the theoretical concern.

Legal Status and Off-Label Use

In the United States, both testosterone and HGH are controlled substances, but with different legal frameworks. Testosterone is a Schedule III controlled substance and can be prescribed off-label for conditions a physician deems appropriate. HGH, however, has a unique restriction under federal law: it can legally be prescribed only for specific FDA-approved indications, such as adult growth hormone deficiency, AIDS-related wasting, and short bowel syndrome. Prescribing HGH for anti-aging purposes or general performance enhancement is illegal under the same statute, even with a prescription.

The American Association of Clinical Endocrinologists has noted an unprecedented rise in off-label use and misuse of both testosterone and growth hormone, with testosterone often promoted for symptoms like low energy and reduced libido, and GH used in attempts to improve athletic performance or counteract aging.¹⁸ Anti-aging clinics frequently offer combination protocols that push the boundaries of what is medically indicated. In competitive sports, both substances are banned by the World Anti-Doping Agency, and GH is reportedly used often in combination with anabolic steroids at high doses for extended periods in doping contexts.¹⁹

How Men and Women Respond Differently

Most studies of combined HGH and testosterone have enrolled men, so the evidence base for women is thinner. The JAMA trial that included both sexes found some notable differences. In men, the combination of GH and testosterone produced the largest lean body mass gain (about 4.3 kilograms) and the only significant improvement in aerobic capacity. In women, GH combined with hormone replacement therapy produced trends toward improved aerobic capacity and strength, but neither reached clear statistical significance.⁴

Side effects also differed by sex. Edema was the standout problem for women on GH-containing regimens, affecting nearly 40% of women in the GH groups versus none taking placebo. Men were more prone to carpal tunnel symptoms and joint pain. Glucose intolerance was predominantly a male problem in this trial, but the women received estrogen-progesterone replacement rather than testosterone, so direct comparisons are limited. Women who are prescribed testosterone (at much lower doses than men) alongside GH would face a different risk calculation that has barely been studied in controlled trials.

Psychological and Cognitive Effects

Beyond body composition, GH replacement has been linked to improvements in mood and cognitive performance. In adults with growth hormone deficiency, six months of GH therapy significantly improved scores on mood scales and cognitive tests, with improvements in vigor correlating with increases in IGF-1 concentration.²⁰ Testosterone replacement has its own body of evidence showing improvements in energy, mood, and sexual function in men with documented deficiency. Whether the combination produces greater psychological benefits than either alone has not been rigorously tested. The mood improvements observed in GH studies likely reflect correction of a deficit rather than an enhancement effect, which means someone with normal GH levels should not expect a psychological boost from supplementation.

The Cost Factor

Practical barriers to combined therapy extend well beyond medical risks. Growth hormone therapy is expensive. An analysis of GH therapy for idiopathic short stature in children estimated the incremental cost at roughly $52,634 per inch of height gained, or about $100,000 per child overall.²¹ Adult dosing for approved indications runs into thousands of dollars per month, and insurance coverage for GH is tightly restricted to documented deficiency with confirmatory testing. Testosterone therapy is far less expensive, but adding GH on top can push monthly costs well above what most people anticipate. Anti-aging clinics that prescribe both often operate on a cash-pay model, sidestepping insurance entirely. If you are considering this route, the financial commitment is substantial and ongoing, because the body composition benefits largely reverse when you stop treatment.

The reversal upon cessation is worth emphasizing. The lean mass gains and fat loss seen in trials reflect what happens while you are actively receiving the hormones. There is no evidence that a “course” of combined HGH and testosterone produces permanent body composition changes once you stop. This makes the cost calculation not a one-time investment but a recurring expense for as long as you want to maintain the effects, layered on top of the medical monitoring (blood work, prostate screening, glucose checks) that responsible prescribing requires.

1
PubMed Central. Testosterone and growth hormone improve body composition and muscle performance in older men
2
The Journal of Clinical Endocrinology & Metabolism. Single and Combined Effects of Growth Hormone and Testosterone Administration on Measures of Body Composition, Physical Performance, Mood, Sexual Function, Bone Turnover, and Muscle Gene Expression in Healthy Older Men
3
The Journal of Clinical Endocrinology & Metabolism. The Effects of Growth Hormone and/or Testosterone in Healthy Elderly Men: A Randomized Controlled Trial
4
JAMA. Growth Hormone and Sex Steroid Administration in Healthy Aged Women and Men: A Randomized Controlled Trial
5
Frontiers in Physiology. Links Between Testosterone, Oestrogen, and the Growth Hormone/Insulin-Like Growth Factor Axis and Resistance Exercise Muscle Adaptations
6
PubMed. Growth hormone and testosterone interact positively to enhance protein and energy metabolism in hypopituitary men
7
The Journal of Clinical Endocrinology & Metabolism. Interaction between Testosterone and Growth Hormone on Whole-Body Protein Anabolism Occurs in the Liver
8
PubMed Central. Long-term Safety of Testosterone and Growth Hormone Supplementation: A Retrospective Study of Metabolic, Cardiovascular, and Oncologic Outcomes
9
The Journal of Clinical Endocrinology & Metabolism. Independent and Combined Effects of Testosterone and Growth Hormone on Extracellular Water in Hypopituitary Men
10
PubMed Central. Effects of anabolic steroids, testosterone, and HGH on blood lipids and echocardiographic parameters in body builders
11
PubMed Central. Recovery of spermatogenesis following testosterone replacement therapy or anabolic-androgenic steroid use
12
PubMed Central. Strategies for Reversing Exogenous Testosterone-Induced Infertility
13
PubMed Central. Combined effects of growth hormone and testosterone replacement treatment in heart failure
14
Neurology: Neurogenetics. Study of Testosterone and Recombinant Human Growth Hormone in Facioscapulohumeral Muscular Dystrophy
15
PubMed. Comparison of the anabolic effects and complications of human growth hormone and the testosterone analog, oxandrolone, after severe burn injury
16
PubMed. Effects of growth hormone and testosterone on cortical bone formation and bone density in aged orchiectomized rats
17
PubMed Central. Growth hormone and prostate cancer: Guilty by association?
18
Endocrine Practice. AACE Position Statement Off-Label Use and Misuse of Testosterone, Growth Hormone, Thyroid Hormone, and Adrenal Supplements: Risks and Costs of a Growing Problem
19
PubMed. A robust test for growth hormone doping–present status and future prospects
20
PubMed Central. Psychological functioning after growth hormone therapy in adult growth hormone deficient patients: endocrine and body composition correlates
21
JAMA Network. Estimated cost-effectiveness of growth hormone therapy for idiopathic short stature