Cortisol and stress: what the link is and what a test can show
Cortisol is called the stress hormone because your body releases it as part of its stress response. That part is well established. What is less clear is what a cortisol number says about your own stress, and whether long-lasting stress keeps cortisol high.
This page explains the link as far as the evidence goes, where studies disagree, and when symptoms call for a clinician rather than a guess about cortisol.
Cortisol AM and PM
A morning result and a later one, because cortisol changes through the day. Follow the times on your lab order.
$129
A cortisol result can't measure stress. It shows your level at the time of each draw. If you take a steroid medicine, ask your prescriber how it affects results.
See this test at HealthLabsPrice checked November 2026. Not available in ND, RI, NY, NJ, MD and HI. We earn a commission on sales.
How stress raises cortisol
When the brain registers a threat, the hypothalamus signals the pituitary gland, the pituitary releases ACTH, and ACTH tells the adrenal glands to make cortisol. This chain is the HPA axis. A 2023 review in Frontiers in Endocrinology calls cortisol release the best-characterised marker of the HPA axis response to psychosocial stress (Front Endocrinol, 2023). The page on the HPA axis covers the chain in more detail.
Cortisol is only part of the response. MedlinePlus says the hormones released in stress make you alert and ready to act, and can raise your blood pressure, heart rate and blood sugar.
You can see the link in a lab. In a 2024 study in BMC Psychology, 48 adult Japanese men took an online social stress test, with a speech and a maths task. On average, their self-rated stress and their salivary cortisol both rose afterward (BMC Psychol, 2024). It was a small study of volunteers without known illness, so it shows the pattern rather than sizing it.
The same idea explains a rule on cortisol test pages. MedlinePlus says stress and exercise can raise your cortisol, so you may need to rest before a test. It lists stress with pregnancy, exercise, hot and cold temperatures and some medicines, such as birth control pills, as things that can change a result without a disease behind it.
Does long-lasting stress keep cortisol high?
Plenty of articles say yes. The research is less tidy.
- A 2023 review of stress and cognition describes the stress literature in general as having “heterogeneous findings” about the effects of stress on the brain and body. It also notes that human studies have shown positive correlations between psychosocial stress and cortisol levels (Front Endocrinol, 2023).
- A 2023 review in Cells proposes that over time chronic stress blunts the body’s response to cortisol and disturbs its daily rhythm. It draws heavily on animal models, and it presents the link to depression as a hypothesis (Cells, 2023).
- A systematic review of hair cortisol after trauma looked at 31 studies and 3,576 people. Higher cortisol fit people with recent or ongoing trauma or high-stress circumstances. For trauma further in the past, results were more mixed: some studies found lower cortisol and some found no difference. The authors point to methodological limits (Curr Neuropharmacol, 2023).
So the fair summary is this. Cortisol tends to be higher during and soon after a stressor. For long-term stress the picture is unsettled, and some people’s levels end up lower than expected. That is why one number can’t tell you how stressed you are.
Does cortisol cause stress?
The sources describe the chain the other way round: stress sets off cortisol release. None of the sources used for this page show that a cortisol level makes a person feel stressed.
There is one clear exception, and it involves a medical condition. NIDDK lists depression or other mood changes, and memory loss or trouble concentrating, among the complications of Cushing’s syndrome. That is the condition of too much cortisol over a long period. It is rare. NIDDK gives an estimate of about 40 to 70 people in every million for the kind caused inside the body, and says the most common cause overall is long-term, high-dose use of steroid medicines. It also brings physical signs, such as easy bruising and wide purple stretch marks, which are listed on the high cortisol page.
The link also appears at the other end. NIDDK lists irritability and depression among the symptoms of adrenal insufficiency, which is too little cortisol. See low cortisol.
What “chronically high cortisol” means in medicine
Online, the phrase often means stress. In medicine, too much cortisol over a long period usually means Cushing’s syndrome, and NIDDK says the most common cause is long-term, high-dose use of cortisol-like medicines. MedlinePlus adds that high cortisol levels can also come and go in some people, a pattern called pseudo-Cushing syndrome. It names depression, anxiety, alcohol use disorder, poorly controlled diabetes and obesity as possible causes.
That matters if you are thinking of testing. A high result in someone who is stressed, anxious or low in mood doesn’t mean Cushing’s syndrome, and a normal one doesn’t rule out a problem. Both go to a clinician.
Can a cortisol test show how stressed you are?
No. MedlinePlus says a cortisol test is used to help diagnose or rule out conditions that cause too much or too little cortisol: Cushing syndrome, Addison disease and secondary adrenal insufficiency. It also says a cortisol test alone can’t identify the cause of an abnormal level. A blood result shows your level when the sample was taken, and that depends on the time of day, recent stress or exercise, and what you take.
A morning sample plus a later one shows how your level changes through the day, which answers a different question. See AM and PM timing. Saliva, urine, hair and wearable tests answer different questions again, covered in saliva, urine and hair tests and wearables. Whichever you pick, a result is something to take to a clinician. It is not a stress score.
Cortisol and other parts of the body
Each of these pages looks at one link people ask about, with the evidence and its limits.
- Cortisol and sleep
What studies find about sleep loss, insomnia and cortisol.
- Cortisol and anxiety
What is and isn't known about cortisol and mood conditions.
- Cortisol and hair loss
What the evidence does and doesn't show.
- Cortisol and blood sugar
How cortisol affects blood sugar, and where it doesn't.
- Coffee and cortisol
What trials of coffee and caffeine found.
- Alcohol and cortisol
What a meta-analysis found.
- Cortisol and fatigue
Tiredness, low cortisol and adrenal fatigue.
- Cortisol and inflammation
Cortisol, the immune system and steroid medicines.
- Cortisol and blood pressure
What is known about cortisol and blood pressure.
- Exercise and cortisol
What is known about exercise and cortisol.
- Fasting and cortisol
What is known about fasting and cortisol.
- Cortisol and the brain
What is known about cortisol, memory and thinking.
- Cortisol and libido
What is known about cortisol and sex drive.
- Cortisol and pain
What is known about cortisol and pain.
- Cortisol and skin
What is known about cortisol and the skin.
- Cortisol and the gut
What is known about cortisol and the gut.
When to see a clinician
For stress itself, MedlinePlus advises asking a health care provider for help if you have severe symptoms for two weeks or more, such as:
- trouble sleeping
- changes in eating that cause unwanted changes in weight
- trouble getting out of bed because of your mood
- difficulty focusing
- losing interest in things you usually enjoy
- not being able to do your usual daily activities
MedlinePlus says to get help right away if stress is causing thoughts of suicide, a feeling that you can’t cope, or more drug or alcohol use than usual. In the US, you can call or text 988, the 988 Suicide & Crisis Lifeline, or call 911 in an emergency.
A hormone problem is a separate question. Easy bruising, wide purple stretch marks, a rounded face and weak muscles are listed for Cushing’s syndrome. Long-lasting fatigue, muscle weakness, loss of appetite, weight loss and abdominal pain are listed for too little cortisol. See high cortisol and low cortisol. Vomiting you can’t stop, fainting or severe weakness need urgent care. Don’t wait for a test. See adrenal crisis.
If you take a steroid medicine, never stop or change it because of anything on this page. Ask your prescriber.
Cortisol AM and PM
$129
A cortisol result can't measure stress. It shows your level at the time of each draw. If you take a steroid medicine, ask your prescriber how it affects results.
See this test at HealthLabsPrice checked November 2026. Not available in ND, RI, NY, NJ, MD and HI. We earn a commission on sales.
Keep reading
- Cortisol and sleep: what studies show and what they don't
Cortisol follows a daily rhythm tied to sleep. What studies of short sleep and insomnia found, where results conflict, and when to see a clinician.
- Cortisol and anxiety: what is known, and what isn't
Can cortisol cause anxiety? What studies of anxiety, depression, PTSD and ADHD find about cortisol, where results conflict, and when to see a clinician.
- Cortisol test: which test answers which question
How a cortisol test works, which type fits your question, when to have it, how to order, and why one result can't diagnose Cushing's or Addison's.
- High cortisol symptoms: what the signs are and how it is tested
The signs doctors link to too much cortisol, the common symptoms that don't point to it, and why one blood cortisol can't diagnose or rule out Cushing's.
- Alcohol and cortisol: what the research shows
Does alcohol raise cortisol? What a 2025 meta-analysis found, how heavy drinking can mimic Cushing's syndrome on tests, and when to see a clinician.
- Cortisol and blood pressure: what the link is and when to see a clinician
How cortisol and blood pressure are linked, what is and isn't known, why aldosterone is a more common hormone cause, and when to see a clinician.
- Cortisol and blood sugar: how the two are linked
Does cortisol raise blood sugar? What stress, steroid medicines and Cushing's syndrome do to glucose, what a genetic study found about diabetes, and which tests help.
- Cortisol and exercise: why a hard workout raises it and why it matters for a test
Does exercise raise cortisol? What studies say about intensity, HIIT and running, how long the rise lasts, and what it means before a cortisol blood test.
- Cortisol and fasting: what studies show and what it means for a test
Does fasting raise cortisol? Studies of Ramadan, time-restricted eating and low-carb diets disagree. Also, whether to fast before a cortisol blood test.
- Cortisol and fatigue: when tiredness is and isn't a hormone problem
Does cortisol make you tired? What low cortisol, high cortisol, burnout and adrenal fatigue claims do and don't show, and which causes of tiredness to check first.
- Cortisol and libido: what is known about stress hormones and sex drive
What is known about cortisol and libido: lowered interest in sex in Cushing's syndrome and adrenal insufficiency, other common causes, and when to see a clinician.
- Cortisol and pain: what is known about headaches, joint pain and sweating
Does cortisol cause pain, headaches or joint and hip pain? What the evidence says, where studies conflict, and when pain is a reason to see a clinician.
- Cortisol and skin: bruising, stretch marks, rashes and what the evidence shows
How cortisol relates to skin changes: bruising and stretch marks in Cushing's syndrome, darkening in Addison's disease, and the mixed evidence on rash, eczema and hives.
- Cortisol, bloating and digestion: what is known and when to see a clinician
Does cortisol cause bloating, stomach pain, constipation or diarrhea? What the evidence shows, where studies disagree, and when digestive symptoms need a clinician.
- Cortisol, memory and brain fog: what is known and when to see a clinician
What research says about cortisol, memory and brain fog: effects in Cushing's syndrome, mixed findings in healthy people, other causes and when to see a clinician.
- Does coffee raise cortisol? What the studies found
Does coffee or caffeine raise cortisol? What a trial of daily coffee drinkers found, where other studies disagree, and what it means for a cortisol test.
- Does cortisol cause inflammation? What it does to the immune system
Is cortisol anti-inflammatory? How cortisol limits inflammation, why long-term stress studies are mixed, and what steroid medicines do to immunity.
- Does high cortisol cause hair loss? What the evidence shows
Can high or low cortisol cause hair loss? What reviews propose, what the clinical sources list, the common causes to rule out and when to see a clinician.
Sources
- Stress. Source: MedlinePlus, National Library of Medicine
- Cortisol Test. Source: MedlinePlus, National Library of Medicine
- Cushing's Syndrome (NIDDK)
- Adrenal Insufficiency & Addison's Disease: Symptoms & Causes (NIDDK)
- Understanding the relationships between physiological and psychosocial stress, cortisol and cognition (Front Endocrinol, 2023, CC BY)
- The Role of Cortisol in Chronic Stress, Neurodegenerative Diseases, and Psychological Disorders (Cells, 2023, CC BY)
- Hair Cortisol Research in Posttraumatic Stress Disorder: 10 Years of Insights and Open Questions. A Systematic Review (Curr Neuropharmacol, 2023, CC BY)
- No significant difference in salivary cortisol response on the Trier Social Stress Test-Online based on coffee consumption habits (BMC Psychol, 2024, CC BY)
- I'm So Stressed Out! Fact Sheet (NIMH)