What causes high cortisol levels? The most common cause is medicine: taking corticosteroids such as prednisone at high doses for a long time.
Cortisol also rises with stress, exercise, pregnancy, lost sleep and some birth control pills. Long-lasting high cortisol made by the body itself usually points to a tumor, most often in the pituitary gland.
Only a doctor’s tests can confirm that your cortisol is truly high. Symptoms like weight gain and fatigue have many causes, and a single number on a lab report is rarely the full answer.
What cortisol does and when it normally peaks
Cortisol is made by the adrenal glands, two small glands that sit on top of your kidneys. According to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), it helps maintain blood pressure, regulate blood sugar, reduce inflammation and turn food into energy.
Your level is not flat across the day. MedlinePlus notes that cortisol is normally highest in the morning and much lower by around 4 p.m., which is why doctors often draw blood twice on the same day.
Video: American Association of Clinical Endocrinology
Steroid medicines: the most common cause by far
Glucocorticoids, also called corticosteroids or steroids, act like cortisol in the body. NIDDK names their long-term, high-dose use as the most common cause of Cushing’s syndrome, the condition of too much cortisol over a long period.
These medicines treat asthma, rheumatoid arthritis, lupus and many other conditions, and they protect transplanted organs from rejection. NIDDK reports that more than 10 million Americans take glucocorticoids each year.
MedlinePlus lists pills, IV drips, joint injections, enemas, skin creams, inhalers and eye drops, with prednisone, dexamethasone and prednisolone as common examples.
Do not stop a steroid on your own. MedlinePlus warns that suddenly stopping corticosteroids after long use, usually more than 2 weeks, can trigger adrenal crisis, which is life-threatening.
Any change to the dose goes through the prescriber.
Stress, exercise, lost sleep and other everyday triggers
Your body releases cortisol as part of the normal stress response. MedlinePlus lists stress, exercise, pregnancy, hot and cold temperatures and certain medicines, such as birth control pills, as factors that can change a cortisol result.
This is why your provider may ask you to rest before the test. A hard workout or a tense morning can push a single reading up without any disease behind it.
For the diet side, our guide to cortisol triggering foods covers what the evidence does and does not support.
Sleep loss changes the cortisol curve the next day. In a 1997 study in the journal Sleep (Leproult and colleagues), young men had their cortisol measured after a normal night, a night cut to 4 hours, and a night with no sleep.
After partial sleep loss, evening cortisol between 6 p.m. and 11 p.m. the next day was 37% higher than the evening before.
After a full night awake it was 45% higher, and the drop that normally comes before sleep started at least 1 hour later.
The study covered young men and one night of lost sleep, so it says nothing about long-term effects. Our guide to magnesium before bed covers one sleep topic in more detail.
Tumors and other medical causes
When the body itself makes too much cortisol, doctors call it endogenous Cushing’s syndrome. NIDDK describes it as rare, with estimates of about 40 to 70 people per million.
It most often affects adults aged 30 to 50, and about three times as many women as men.
NIDDK lists three tumor types behind it:
- Pituitary tumors that make too much ACTH, the hormone that tells the adrenals to release cortisol. These cause 8 out of 10 cases not caused by medicine and are called Cushing’s disease. They are noncancerous.
- Ectopic ACTH-producing tumors outside the pituitary, most often in the lungs, sometimes in the pancreas, thyroid or thymus. These may be cancerous.
- Adrenal tumors that make cortisol directly. Most are benign, but some are cancerous.
NIDDK and MedlinePlus describe pseudo-Cushing’s syndrome, where cortisol runs high off and on in people with depression, anxiety, heavy alcohol use, poorly controlled diabetes or obesity, without the long-term disease.
| Cause | Where the extra cortisol comes from | Typical pattern | What usually happens next |
|---|---|---|---|
| Corticosteroid medicines | Outside the body (exogenous) | Lasts as long as the treatment | Prescriber adjusts or tapers the dose |
| Stress, exercise, heat or cold | Normal stress response | Short-lived | Provider may ask you to rest before testing |
| Sleep loss | Delayed evening drop | Next-day evening rise | Evening results read in light of sleep |
| Pregnancy, birth control pills | Factors MedlinePlus says affect results | Lasts while the factor is present | Provider reads results in that context |
| Pseudo-Cushing’s syndrome | Linked to depression, alcohol, diabetes, obesity | Comes and goes | Follow-up tests (dexamethasone-CRH) separate it from Cushing’s syndrome |
| Pituitary, ectopic or adrenal tumor | Inside the body (endogenous) | Persistent | Imaging and specialist care |
Source: NIDDK, Cushing’s Syndrome; MedlinePlus, Cortisol Test and Exogenous Cushing Syndrome; Leproult et al., Sleep, 1997. Opened 3 November 2026.
How doctors confirm high cortisol
According to MedlinePlus, a cortisol test alone cannot diagnose the cause of an abnormal level. NIDDK adds that no single test is perfect, so doctors usually run two of these:
- A 24-hour urinary free-cortisol test, where you collect all your urine for a day.
- A late-night salivary cortisol test, which checks whether cortisol drops in the evening as it normally should.
- A low-dose dexamethasone suppression test, where a blood draw the next morning shows whether cortisol falls after a small dose of a steroid.
Your doctor will first ask whether you take glucocorticoids or have had steroid injections, and rule that out before ordering tests.
NIDDK links Cushing’s syndrome to high blood pressure, type 2 diabetes, bone loss and infections. Signs worth reporting include wide purple stretch marks, easy bruising, a rounder face and, per MedlinePlus, weak hip and shoulder muscles.
Cortisol also helps control inflammation, a topic we look at from the food side in do tomatoes cause inflammation. For any personal decision, talk with your doctor.
Frequently asked questions
Can stress alone cause high cortisol levels?
Yes, for a while. MedlinePlus lists stress as a factor that raises cortisol, which is why you may be asked to rest before a test. Ongoing high cortisol with physical changes needs a doctor’s evaluation for other causes.
Do steroid inhalers or creams raise cortisol?
MedlinePlus lists inhalers and skin creams among the forms of glucocorticoids linked to exogenous Cushing’s syndrome, and NIDDK ties the syndrome mainly to long-term, high-dose use. Do not stop or cut them yourself; ask your prescriber.
Is one high cortisol blood test enough for a diagnosis?
No. Cortisol changes through the day and with stress, sleep and medicine. NIDDK says doctors usually confirm with two different tests before looking for a cause.
