Cortisol, the body’s primary stress hormone, generally drives testosterone down. The relationship is not a simple seesaw where one always rises as the other falls, but the dominant pattern across decades of research is clear: sustained elevations in cortisol suppress testosterone production through multiple pathways, from the brain down to the cells that manufacture testosterone in the testes. The picture gets more interesting when you look at short bursts of stress, at differences between men and women, and at the behavioral consequences of having both hormones in play at once.
How Cortisol Suppresses Testosterone Production
Cortisol belongs to a family of hormones called glucocorticoids, and it acts on testosterone through at least two distinct routes. The first is in the brain and pituitary gland. The hormonal cascade that triggers testosterone production starts with a brain signal (GnRH) that tells the pituitary to release luteinizing hormone (LH), which then travels to the testes and prompts testosterone synthesis. Stress-level cortisol disrupts this cascade early: it reduces the pituitary’s responsiveness to that brain signal, so less LH gets released, and less testosterone gets made downstream.1PubMed Central. Insight into the neuroendocrine site and cellular mechanism by which cortisol suppresses pituitary responsiveness to gonadotropin-releasing hormone
The second route is more direct. Even if LH makes it to the testes, glucocorticoids can suppress the cells that actually produce testosterone, called Leydig cells. Lab studies show that elevated glucocorticoids cause rapid declines in testosterone output from these cells.2PubMed Central. Rapid mechanisms of glucocorticoid signaling in the Leydig cell In cell culture experiments, synthetic glucocorticoids reduced testosterone production by up to 40% in a time-dependent fashion.3PubMed. Effect of glucocorticoids on testosterone production by porcine Leydig cells in primary culture So cortisol hits testosterone from above, by throttling the brain-to-pituitary signal, and from below, by impairing the factory floor itself.
The two hormonal systems involved, the stress axis and the reproductive axis, are in constant communication. That crosstalk means stress does not just incidentally affect testosterone; it actively redirects the body’s resources away from reproduction and toward survival.4PubMed Central. Stress, hypothalamic-pituitary-adrenal axis, hypothalamic-pituitary-gonadal axis, and aggression From an evolutionary standpoint, this makes sense: if you are running from a predator or starving, your body has no business investing in reproduction.
Why Short Bursts of Stress Sometimes Raise Testosterone
The suppressive effect of cortisol on testosterone is most reliable during prolonged or severe stress. Acute stress tells a messier story. In studies of military officer trainees, both cortisol and testosterone rose during short-term stressors like social evaluation tasks and brief field exercises. But when the same trainees endured weeks of intensive training, their morning testosterone dropped significantly, only recovering after the stress load eased.5PubMed. Testosterone and cortisol responses to acute and prolonged stress during officer training school
Something similar shows up in exercise research. A single session of high-volume resistance training (the kind designed for muscle growth) can raise both testosterone and cortisol simultaneously.6The Journal of Strength & Conditioning Research. The Salivary Testosterone and Cortisol Response to Three Loading Schemes This seems contradictory if you think of cortisol as purely testosterone-killing, but it reflects the fact that the body’s acute mobilization response ramps up multiple hormonal systems at once. The trouble starts when the stress never lets up. Chronic overtraining, prolonged sleep deprivation, extreme caloric restriction: these create the sustained cortisol elevation that consistently pulls testosterone down.
What Cushing’s Disease Teaches Us
The clearest clinical demonstration of cortisol crushing testosterone comes from Cushing’s syndrome, a condition in which the body produces far too much cortisol. In men with Cushing’s, testosterone levels are dramatically lower than in healthy men. One study of twelve men with active Cushing’s disease found their average testosterone was roughly a quarter of the normal value. When their excess cortisol was successfully treated, testosterone levels recovered, confirming that the suppression was directly caused by the cortisol excess and was not permanent damage.7PubMed. Reversible gonadotropin deficiency in male Cushing’s disease
A more recent study put finer numbers on the problem. Hypogonadism, meaning clinically low testosterone, was present in over 80% of men with the most severe form of Cushing’s and in roughly a third even in milder adrenal-driven cases. Total, free, and bioavailable testosterone were all significantly lower than in matched controls.8PubMed. Impact of Cushing’s syndrome on the gonadotrope axis and testicular functions in men Cushing’s is relatively rare, but it functions as a natural experiment showing what happens when cortisol runs unchecked for months or years.
Prescription Steroids and Testosterone
You do not need a disease to experience cortisol-driven testosterone suppression. Millions of people take glucocorticoid medications like prednisone, prednisolone, and dexamethasone for conditions ranging from asthma to autoimmune disorders. These drugs mimic cortisol’s effects, and their impact on testosterone is well documented.
Men on long-term oral prednisolone had testosterone levels about a third lower than healthy controls in one study.9PubMed. Testosterone levels during systemic and inhaled corticosteroid therapy Another analysis found that patients who took oral dexamethasone at a cumulative dose of roughly 19 mg had over seven times the risk of being diagnosed with hypogonadism.10PubMed Central. Effect of exogenous glucocorticoids on male hypogonadism Even a single dose of prednisolone was enough to reduce the testosterone-to-LH ratio in healthy men, consistent with direct impairment of Leydig cell function on top of whatever the exercise protocol itself was doing.11PubMed Central. Single-dose prednisolone alters endocrine and haematologic responses and exercise performance in men
Inhaled corticosteroids, used by many people with asthma, appear to be a different story. Because very little of the drug reaches the bloodstream, the systemic hormonal effects are much smaller. If you use a steroid inhaler for asthma, that is not likely the same concern as taking oral prednisone for months. But anyone on prolonged systemic glucocorticoid therapy should be aware that testosterone suppression is a real and common side effect, not a fringe risk.
Sleep Deprivation and Energy Deficit
Two of the most common lifestyle factors that raise cortisol and lower testosterone simultaneously are poor sleep and severe caloric restriction. A study of acute sleep deprivation found that a single night without sleep increased cortisol by about 21% while dropping testosterone by about 24%.12PubMed Central. The effect of acute sleep deprivation on skeletal muscle protein synthesis and the hormonal environment That is a striking swing from just one bad night. Chronic partial sleep restriction, the kind most shift workers and overscheduled people experience, likely compounds this over time, though the exact dose-response curve varies by individual.
Energy deficit paints an even more dramatic picture. During an intensive eight-week military training course involving heavy exertion and inadequate food, participants lost about 8% of their body weight and saw their testosterone drop by roughly 70%. Cortisol rose alongside markers of systemic stress.13The Journal of Clinical Endocrinology & Metabolism. Dysregulation of the Hypothalamic–Pituitary–Testicular Axis due to Energy Deficit This kind of extreme deficit is unusual in civilian life, but milder versions play out in crash diets and eating disorders. The body interprets prolonged energy shortage as a threat and shifts hormonal resources accordingly: cortisol up, testosterone down.
The Testosterone-to-Cortisol Ratio in Sports Medicine
Sports scientists have been tracking the ratio of testosterone to cortisol for decades as a rough indicator of whether an athlete is in a state of recovery and adaptation or one of overreaching and breakdown. A declining ratio, meaning testosterone falling relative to cortisol, has been linked to overtraining syndrome, where performance deteriorates despite continued hard work.14PubMed Central. The Testosterone: Cortisol Ratio – A Tool with Practical Use and Research Potential in Endocrinology
The ratio is far from a perfect diagnostic tool. It varies with time of day, sleep quality, recent meals, and psychological state, making single measurements unreliable. But tracking it over time in an individual athlete can reveal trends. A coach who sees a persistent drop in the T-to-C ratio across several weeks of training has a useful warning sign that recovery is not keeping pace with the training load. Research has also explored the ratio’s connection to cardiovascular risk and psychological stress, though those applications remain less established than the overtraining use case.
When Both Hormones Shape Behavior
Beyond the physiology of how much testosterone your body produces, cortisol also appears to change what testosterone does to your behavior. The dual-hormone hypothesis proposes that testosterone’s link to dominance and status-seeking behavior depends on cortisol levels. When cortisol is low, higher testosterone predicts more dominant, status-seeking behavior. When cortisol is high, that association weakens or even reverses.15PubMed Central. Beyond the Challenge Hypothesis: The Emergence of the Dual-Hormone Hypothesis and Recommendations for Future Research
The original studies supporting this idea found that testosterone predicted leadership behavior and competitive dominance only among people with low cortisol. In individuals with high cortisol, higher testosterone was actually associated with less dominance, especially after social defeat.16PubMed. Testosterone and cortisol jointly regulate dominance: evidence for a dual-hormone hypothesis The idea is intuitively appealing: if you are stressed out, the body’s stress system may override or mute the behavioral effects of testosterone, shifting you from approach to avoidance. A meta-analysis examining this hypothesis across multiple domains, including aggression, risk-taking, and psychopathy, has found modest support, though the effect sizes vary and some outcomes show weaker evidence than others.17PubMed. A meta-analytical evaluation of the dual-hormone hypothesis: Does cortisol moderate the relationship between testosterone and status, dominance, risk taking, aggression, and psychopathy?
This line of research matters beyond academic curiosity. It suggests that managing stress is not just about how much testosterone circulates in your blood, but about whether the testosterone you do have actually translates into the confidence, drive, and assertiveness people typically associate with it.
How the Picture Differs in Women
Most of the research on cortisol and testosterone focuses on men, partly because men produce far more testosterone and the clinical effects of suppression are more obvious. But women make testosterone too, primarily from the ovaries and the adrenal glands, and cortisol’s relationship with female androgens has its own characteristics.
In women, the adrenal glands are a proportionally larger source of androgens than in men, so adrenal function has a more direct bearing on androgen levels. A study of infertile women found that adrenal sex hormone precursors, particularly DHEA, were strong predictors of cortisol levels, reflecting a tight coupling between adrenal androgen and cortisol production pathways.18PubMed. Associations between peripheral androgens and cortisol in infertile women In women with polycystic ovary syndrome, the picture is complicated further. Research comparing women with PCOS to controls found that while adrenal-derived androgens and cortisol were similar between the two groups, the ratios of certain adrenal androgens to their ovarian precursors were lower in PCOS, pointing to the ovaries rather than the adrenal glands as the main source of excess testosterone in that condition.19Journal of the Endocrine Society. Interplay of Cortisol, Testosterone, and Abdominal Fat Mass in Normal-weight Women With Polycystic Ovary Syndrome
The upshot is that “cortisol suppresses testosterone” is broadly true in women as it is in men, but the clinical significance is different. Because women’s baseline testosterone is much lower, even small shifts can affect symptoms like libido and energy without meeting any formal diagnostic threshold. And because the adrenal glands play a dual role in producing both cortisol and androgen precursors, chronic stress in women can create a more tangled hormonal picture than the straightforward cortisol-up-testosterone-down pattern seen in men.
Cortisol, SHBG, and Free Testosterone
Total testosterone is not the whole story. Much of the testosterone in your blood is bound to a carrier protein called sex hormone-binding globulin (SHBG), which renders it inactive. Only the unbound “free” fraction is available to act on tissues. Cortisol influences this equation too. Research in middle-aged men found that cortisol secretion capacity was negatively associated with SHBG levels, and that free testosterone was positively associated with free cortisol. Cortisol responses alone explained about a third of the variation in SHBG levels, and together with age, nearly half.20ScienceDirect (Elsevier). Serum sex hormone-binding globulin, cardiovascular risk factors, and adrenal cortisol responses to dexamethasone and corticotropin
This adds a layer of complexity. Even if total testosterone does not change dramatically, shifts in SHBG driven by cortisol or related metabolic factors can alter how much free testosterone is available. It also means that looking at total testosterone alone, which is what most standard lab panels report, can miss part of the picture. Someone with normal total testosterone but elevated cortisol might still experience symptoms of low androgen activity if more of that testosterone is bound up.
Ashwagandha and the Supplement Question
Given how reliably chronic stress suppresses testosterone, an obvious question is whether lowering cortisol can bring testosterone back up. The supplement most studied for this is ashwagandha (Withania somnifera), an adaptogenic herb from the Ayurvedic tradition. A randomized, placebo-controlled trial in overweight men found that ashwagandha supplementation was associated with a roughly 15% greater increase in testosterone compared to placebo, though the between-group difference in cortisol did not reach significance in that particular study.21PubMed Central. A Randomized, Double-Blind, Placebo-Controlled, Crossover Study Examining the Hormonal and Vitality Effects of Ashwagandha (Withania somnifera) in Aging, Overweight Males
A broader systematic review and meta-analysis pooling over 20 trials found that ashwagandha did significantly reduce cortisol. The testosterone increase was significant in men but not in women, with a meaningful gender difference in the response.22PubMed. Hormonal Modulation with Withania somnifera: Systematic Review and Meta-Analysis of Randomized-controlled Trials Whether the testosterone rise is a direct pharmacological effect of the herb or an indirect consequence of lowered cortisol is not fully settled, but the pattern is at least consistent with the cortisol-testosterone relationship described throughout this article.
It is worth being realistic about the magnitude. The testosterone increases seen with ashwagandha are modest, typically in the range of tens of nanograms per deciliter, not hundreds. For a man with clinically low testosterone caused by a medical condition, a supplement is unlikely to be sufficient. For someone whose testosterone is on the lower side due to chronic stress, poor sleep, or overtraining, addressing those root causes directly, through better sleep, sensible training, adequate nutrition, and stress management, is likely to do more than any capsule. Ashwagandha may offer a supplementary boost, but it is not a substitute for fixing the lifestyle factors that pushed cortisol up in the first place.
Why the Relationship Is Not Perfectly Inverse
If you measure cortisol and testosterone in a large group of people at a single point in time, you will not find a perfect negative correlation. Some people walk around with above-average levels of both. Others have low levels of both. The inverse pattern emerges most clearly under conditions of sustained stress and in clinical extremes like Cushing’s syndrome, not as a rigid law governing every individual at every moment.
Part of the reason is timing. Cortisol’s suppressive effects on testosterone take time to manifest. A cortisol spike from a scary meeting or a hard workout may come and go before testosterone has meaningfully budged. Another part is individual variation: genetics, body composition, age, sleep quality, and nutritional status all influence how responsive your hormonal axes are to stress. Two people exposed to the same stressor can have very different hormonal outcomes. The cortisol-testosterone relationship is a strong biological tendency, not a mechanical law, and that distinction matters when people try to use a single cortisol reading to predict their testosterone level or vice versa.