High cortisol symptoms: the signs, the causes and when to see a doctor

Too much cortisol over a long period causes a recognisable set of changes: fat building up around the tummy, upper back and face while the arms and legs stay thin, a round red face, easy bruising, stretch marks and weak muscles at the tops of the arms and legs.¹ Because cortisol also pushes up blood pressure and blood sugar, those tend to rise too.² When these changes come from a sustained excess of cortisol, the condition is called Cushing's syndrome. It is rare, and its most common cause is not a gland problem but long-term steroid medicine.¹ Cortisol also rises for a while with stress, lost sleep, alcohol and illness, which is the body working as it should. If you have several of the signs below, see a GP: only a doctor's tests can confirm or rule out Cushing's syndrome.

What are the signs of high cortisol?

The NHS lists these as the main symptoms of Cushing's syndrome:¹

• more fat on the neck, upper back, chest and tummy, with arms and legs that look thin
• a red, round face
• skin that bruises easily, and stretch marks
• weak muscles at the tops of the arms and legs
• a low sex drive and changes in mood
• periods that become irregular or stop
• extra hair growth
• in children, weight gain while growth in height slows

These follow from what cortisol does. It raises the amount of sugar available in the blood, breaks down protein and fat, and affects blood vessels and the immune system. A long-term excess therefore leads to fat stored around the middle, muscle wasting, high blood pressure and glucose intolerance, where the body struggles to keep blood sugar in check.²

Many of these signs are common on their own. The Endocrine Society's diagnostic guideline notes that weight gain, depression, high blood pressure, diabetes and irregular periods are frequent in the general population, while the features that most clearly set Cushing's syndrome apart are easy bruising, a flushed red face, weakness of the muscles nearest the trunk, and reddish-purple stretch marks more than 1 cm wide.³ Even these are not unique to Cushing's. The guideline recommends testing people with several features that are getting worse, or with problems unusual for their age, such as high blood pressure or thinning bones in a young adult.³

It also helps to keep the numbers in proportion. European population studies report two to three new cases a year of Cushing's syndrome caused by the body's own cortisol, per million people.³ And in the general population, long-term cortisol is only weakly linked to weight: across more than 26,000 people, the pooled correlation between hair cortisol and body mass index was r = 0.10.⁴ See cortisol and weight for more on that link.

The most common cause: steroid medicines

The most common cause of Cushing's syndrome is taking high doses of steroid medicine, such as prednisolone or hydrocortisone, for a long time.¹ These medicines (glucocorticoids) act like cortisol, and they are widely used: at least 1 per cent of the population takes them long term.⁵ That is why the Endocrine Society recommends that doctors take a full medicine history, including creams, injections and herbal products, before testing anyone for Cushing's syndrome.³

The same medicines are also a leading cause of cortisol being too low. MedlinePlus lists long-term steroid use, or stopping it suddenly, as the most common cause of abnormal cortisol levels.⁶ With long-term treatment the body turns down its own cortisol production, and it may not restart straight away when the medicine stops, a problem called glucocorticoid-induced adrenal insufficiency.⁵

So if you take steroid medicine and notice the signs above, do not stop it or cut the dose on your own. Speak to the doctor who prescribes it. Stopping suddenly can leave you short of cortisol, and very low cortisol can become an emergency. Our guide to low cortisol symptoms explains the warning signs.

Everyday things that raise cortisol for a while

Cortisol is meant to move. It peaks at around 8.30 in the morning and falls to its lowest point near midnight,⁷ and it climbs in response to many ordinary demands. Once a demand passes, cortisol itself helps switch the response off again through a feedback loop in the brain.⁸ Common short-term causes include:

• Stress. In a review of 208 laboratory studies, the biggest and longest-lasting cortisol responses came from tasks that felt uncontrollable and involved being judged by others.⁹
• Lost sleep. After a night of partial or total sleep loss, cortisol the next evening was 37 and 45 per cent higher respectively.¹⁰
• Alcohol. In the Whitehall II study, men's cortisol rose by 3 per cent for every weekly unit they drank.¹¹ In people dependent on alcohol, hair cortisol was three to four times higher during active drinking and returned to normal with abstinence.¹²
• Illness. In critically ill patients in intensive care, cortisol production was 83 per cent higher than in healthy people, and blood levels were 3.5 times higher.¹³
• Hard exercise. Thirty minutes at high intensity raised cortisol by 83 per cent, while low-intensity exercise did not raise it.¹⁴
• Pregnancy and some medicines. MedlinePlus lists pregnancy and medicines such as birth control pills among things that affect cortisol results.⁶ Oral oestrogen raises the protein that carries cortisol in the blood, and in one study total blood cortisol was 67 per cent higher in women taking it.¹⁵

Longer periods of stress show up in long-term cortisol too, but on a different scale from disease. A meta-analysis of hair cortisol studies found levels 22 per cent higher in groups under chronic stress, and 43 per cent higher while the stress was still going on.¹⁶ By contrast, in one study of Cushing's syndrome the average hair cortisol of patients was 106.9 pg/mg, against 8.4 pg/mg in healthy volunteers.¹⁷ The studies used different methods, so the figures are not directly comparable, but the gap is large. Stress still deserves attention in its own right: see cortisol and stress and how to lower cortisol.

When high cortisol symptoms need a doctor

See a GP if you have several of the signs above, if they are getting worse, or if you take steroid medicine and are worried about its effects. Cushing's syndrome is much more common in women than in men, and when it is caused by a growth on the pituitary gland it is called Cushing's disease.¹ It matters to find it, because untreated it raises the risk of heart attack and stroke, high blood pressure, type 2 diabetes, blood clots, thinning bones and kidney stones.¹

A GP can arrange tests of cortisol in blood, urine or saliva, and a specialist may then do further tests and scans.¹ Because cortisol excess can come and go, the guidelines recommend at least two 24-hour urine collections or two late-night saliva samples, or a dexamethasone suppression test, in which a steroid tablet taken the night before should switch off the body's own cortisol by morning.³ Our guide to Cushing's syndrome tests explains each one.

If you take steroid tablets and become suddenly very unwell, with vomiting, confusion, severe weakness or collapse, call 999 (911 in the US) and say that you take steroids.

Why one cortisol test is hard to read

If you simply want to know whether your cortisol has been running high, a single blood or saliva result is a weak guide. Because cortisol swings across the day, a value taken at a random time is hard to interpret.¹⁸ Having blood taken can itself raise it: venepuncture triggers a cortisol response in about 30 to 47 per cent of people.¹⁹ Even 24-hour urine cortisol varied by about 52 per cent from one collection to the next in people with Cushing's disease.²⁰ That is why doctors repeat tests, and why a one-off result, from a clinic or a home kit, should be read with care. Our guide to normal cortisol levels explains the ranges.

Measuring long-term cortisol: what a hair test can and cannot show

If your question is whether your cortisol has been high over recent months, rather than at one moment, hair answers it more directly. Scalp hair grows about 1 cm a month and takes up cortisol as it grows, so the 3 cm nearest the scalp reflect roughly the past three months.²¹ It is also consistent: a person's hair cortisol correlated at r = 0.84 from one month to the next, against 0.38 to 0.61 week to week for saliva and 0.59 to 0.68 for 24-hour urine.²² That makes a hair test the most accurate way to measure long-term cortisol from a single sample.

Hair has also been studied as a test for Cushing's syndrome. In one study a single sample picked out people with the condition with 93 per cent sensitivity and 90 per cent specificity, which the authors judged similar to the standard first-line tests, not better.¹⁷ But hair cortisol is not part of the diagnostic guidelines,³²³ a 2024 expert review said it still needs validating outside research settings,¹⁸ and another study found it could not detect the milder cortisol excess that some adrenal nodules cause, known as mild autonomous cortisol secretion.²⁴ Steroid medicines, including inhalers, nasal sprays and creams, can also change hair results.²⁵

So a hair test can show whether your average cortisol has been high over the past few months, and repeating it later shows whether changes to sleep, work or treatment have moved it. It cannot tell you whether you have Cushing's syndrome, and a normal result does not rule it out. If you have the signs described above, see a doctor whatever a home test shows. Our guide to the hair cortisol test explains how it works.