Too much cortisol in your body typically comes from one of two sources: medications you’re taking or a problem inside your body that disrupts normal hormone signaling. The most common cause, by far, is long-term use of prescription steroids like prednisone or dexamethasone. When the cause is internal, it usually involves a small tumor in the pituitary gland, the adrenal glands, or occasionally elsewhere in the body. A number of everyday health conditions, including chronic stress, depression, and poor sleep, can also push cortisol levels meaningfully higher without involving a tumor at all.
Steroid Medications Are the Most Common Cause
Prescription glucocorticoids are synthetic versions of cortisol, and taking them for weeks or months floods your body with far more of the hormone than it would produce on its own. Prednisone, prednisolone, and dexamethasone are the most widely prescribed, but the problem isn’t limited to pills. These medications come as inhalers, skin creams, eye drops, joint injections, and enemas, and all of them can contribute to excess cortisol if used frequently or at high enough doses.
This is sometimes called exogenous Cushing’s syndrome, meaning the excess cortisol is coming from outside your body rather than from your own glands. The good news is that it’s reversible once the medication is tapered down or stopped, though that process needs to happen gradually under medical supervision because your adrenal glands may have temporarily shut down their own cortisol production.
Pituitary Tumors: The Leading Internal Cause
When excess cortisol originates inside the body, a tiny tumor on the pituitary gland is responsible roughly two thirds of the time. The pituitary is a pea-sized gland at the base of the brain that acts as a master control center for hormone production. These tumors, almost always benign, pump out too much of a signaling hormone called ACTH, which in turn tells your adrenal glands to keep making cortisol even when levels are already high.
Normally, rising cortisol sends a feedback signal to the pituitary telling it to stop releasing ACTH. In people with these tumors, that feedback loop is broken. Genetic mutations in the tumor cells appear to play a role. Research published in Endocrine Reviews found that about 35% of these pituitary tumors carry a specific mutation that causes the cells to overproduce ACTH by interfering with how signaling receptors are recycled inside the cell. The condition is rare overall, affecting roughly 1.2 to 2.4 people per million each year, but it accounts for the majority of non-medication-related cases.
Adrenal Gland Tumors
Your two adrenal glands sit on top of your kidneys and are the organs that actually manufacture cortisol. Sometimes a tumor grows directly on an adrenal gland and produces cortisol on its own, completely bypassing the normal pituitary signaling system. These tumors can be benign (adenomas) or, more rarely, cancerous (carcinomas). Because the tumor is making cortisol independently, your pituitary gland’s ACTH levels actually drop very low, which is one way doctors distinguish this cause from a pituitary problem.
In rare cases, both adrenal glands develop clusters of tiny nodules that overproduce cortisol without any tumor driving the process. This is uncommon but recognized as a distinct cause.
Tumors Elsewhere in the Body
Certain tumors outside the pituitary can start producing ACTH on their own, a condition called ectopic ACTH syndrome. The tumors most commonly responsible include small cell lung tumors, benign carcinoid tumors of the lung, pancreatic islet cell tumors, thymus gland tumors, and a type of thyroid cancer called medullary carcinoma. These cases are rare, but they can cause cortisol levels to spike dramatically because the tumor often produces large amounts of ACTH without any of the normal feedback controls.
Conditions That Raise Cortisol Without a Tumor
Not all high cortisol comes from tumors or medications. Several common health conditions can chronically activate your body’s stress hormone system, producing cortisol levels high enough to show up on lab tests and sometimes cause physical symptoms. Doctors now call this “functional hypercortisolism” because it’s driven by ongoing activation of the stress response rather than by a growth or tumor. The cortisol elevation is usually milder than what tumors produce, and it typically resolves when the underlying condition improves.
Depression
About 50% of people with depression have measurably elevated cortisol, and it’s especially common in people with the melancholic subtype. The connection appears to run through the hippocampus, a brain region involved in mood regulation. Chronic stress and depression can reduce the hippocampus’s ability to regulate the stress hormone axis, leading to persistently high cortisol output. When depression goes into remission, cortisol secretion typically returns to normal.
Chronic Stress and Sleep Loss
Your body’s stress response system is designed to spike cortisol briefly and then shut itself off through a feedback loop. Chronic psychological stress disrupts that loop, keeping cortisol elevated for longer periods than your body can comfortably handle. Sleep deprivation compounds the problem. Even a single night of total sleep loss significantly increases cortisol levels, with the rise most pronounced in the early evening hours, a time when cortisol should be at its lowest. Normal cortisol follows a predictable daily rhythm: it peaks in the morning (7 to 25 mcg/dL) and drops to about 2 to 14 mcg/dL by the afternoon. Sleep loss and chronic stress flatten that curve, keeping evening levels higher than they should be.
Alcohol Use
Heavy, chronic alcohol use raises cortisol through multiple pathways. Alcohol appears to directly stimulate cortisol secretion, and when chronic drinking damages the liver, cortisol metabolism slows down, so the hormone accumulates in the bloodstream. The physical signs can look strikingly similar to Cushing’s syndrome. The distinguishing factor is that most of the abnormalities disappear within one to three weeks of stopping alcohol.
Obesity, Diabetes, and PCOS
Obesity triggers overactivation of the stress hormone axis through several mechanisms, including heightened sensitivity to stress signals and changes in how cortisol is processed in fat tissue. In one study of 190 people with type 2 diabetes, a third had elevated cortisol concentrations. Polycystic ovarian syndrome (PCOS) drives cortisol up through increased breakdown of the hormone, which paradoxically causes the brain to ramp up production to compensate. Eating disorders, particularly anorexia nervosa, activate the stress axis through starvation, producing a pattern of elevated cortisol driven by the body’s response to severe caloric deprivation.
How Doctors Identify the Cause
Figuring out why cortisol is too high involves a step-by-step process. The first question is simply confirming that cortisol is genuinely elevated. One common screening method involves taking a low dose of a synthetic steroid called dexamethasone at 11 p.m. and having blood drawn at 8 a.m. the next morning. In a healthy person, the dexamethasone tells the body to stop making cortisol, so morning levels drop below 1.8 mcg/dL. If cortisol stays above that threshold, it suggests something is overriding the normal feedback system.
Once excess cortisol is confirmed, the next step is measuring ACTH levels in the late afternoon, when they’re normally at their lowest. If ACTH is elevated (above 10 pg/mL), the problem is coming from something that produces ACTH, either a pituitary tumor or an ectopic source. If ACTH is very low (below 5 pg/mL), the adrenal glands themselves are the issue, either a tumor or nodular overgrowth making cortisol independently. This distinction shapes the entire treatment approach.
For people whose cortisol is mildly elevated and who also have depression, obesity, heavy alcohol use, or another condition known to raise cortisol functionally, doctors may recommend treating the underlying condition first and retesting. If cortisol normalizes after weight loss, sobriety, or treatment of depression, no further workup for tumors is needed.