Cortisol and fatigue: when tiredness is and isn't a hormone problem

Does cortisol make you tired? Sometimes, but only in specific medical conditions, and most tiredness has nothing to do with cortisol. Long-lasting fatigue is one of the most common symptoms of too little cortisol (adrenal insufficiency). For too much cortisol, NIDDK’s list of symptoms doesn’t include fatigue. For everyday exhaustion and burnout, studies haven’t found a reliable cortisol signature.

Ferritin

One blood test for your body’s iron stores, a common thing to check when you feel tired.

$29

Tiredness has many causes. If you have repeated vomiting, severe weakness or fainting, get urgent care instead of ordering a test.

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Price checked November 2026. Not available in ND, RI, NY, NJ, MD and HI. We earn a commission on sales.

Tiredness has many causes

MedlinePlus says fatigue is a symptom and not a disease, and that it can be a normal response to physical activity, emotional stress, boredom or lack of sleep. It lists many possible causes, including:

• long-lasting conditions such as diabetes, and heart, liver, kidney and thyroid disease
• anemia
• infections
• sleep apnea and other sleep disorders
• depression and anxiety
• some medicines
• lifestyle habits, such as not getting enough sleep, drinking too much alcohol and having too much caffeine

It advises contacting your provider if you have felt tired for weeks. The provider will ask about your sleep, activities, appetite and exercise, will probably do a physical exam, and will order lab tests.

Low cortisol and fatigue

Yes, in one condition. NIDDK says long-lasting fatigue is a common symptom of adrenal insufficiency. Others on the list include muscle weakness, loss of appetite, weight loss, abdominal pain, low blood pressure that is worse on standing, and low blood sugar. The symptoms come on slowly and can be mistaken for other illnesses. NIDDK says to ask a health care professional about adrenal insufficiency if you always feel tired, weak or are losing weight.

It is not a common reason for being tired. Whether it applies depends on the full picture, which is why the diagnosis rests on a clinician’s work-up and not on how tired you feel. See low cortisol.

Urgent signs. If you are very unwell, with vomiting you can’t stop, severe diarrhea or fainting, get urgent care. NIDDK says people with adrenal insufficiency who take corticosteroid pills need immediate medical attention if they have a severe infection or severe diarrhea, or are vomiting and can’t keep the pills down. Call 911 or go to the nearest emergency room. Don’t wait for a test. See adrenal crisis.

High cortisol and fatigue

NIDDK’s symptom list for Cushing’s syndrome includes weight gain, thin arms and legs, a round face, easy bruising, wide purple stretch marks and weak muscles. Fatigue is not on it. NIDDK does note that symptoms such as fatigue and weight gain have many causes, which is part of why Cushing’s syndrome is hard to diagnose. See high cortisol.

Burnout and “exhaustion”

Burnout is a term for long-term work stress and exhaustion, and people often assume it shows up in cortisol. The one study used for this page found no such link. It was a small 2026 study of healthcare workers in Colombia, which compared morning blood cortisol with burnout scores. Almost all had cortisol within the lab’s normal range, and there was no significant link between cortisol and exhaustion, cynicism or professional efficacy (Int J Environ Res Public Health, 2026). It is a small cross-sectional study from one setting, so it can’t rule out a link. It does fit the next section.

What about “adrenal fatigue”?

“Adrenal fatigue” is the idea that chronic stress wears out the adrenal glands and leaves them unable to make enough cortisol. It is not a recognized diagnosis.

• A 2016 systematic review in BMC Endocrine Disorders looked at 58 studies of cortisol and fatigue. It found conflicting results across most methods, described major flaws in the research and concluded that there is no substantiation for adrenal fatigue as a medical condition (BMC Endocr Disord, 2016).
• A 2024 paper in the Journal of the Endocrine Society says adrenal fatigue has never been scientifically proven to exist. It says the symptom scores and salivary cortisol profiles used to “diagnose” it have never been validated, and that the accepted tests, serum cortisol, ACTH and the ACTH stimulation test, are usually normal in people given the label. It also warns that some “adrenal extract” products contain steroid hormones, which could cause adrenal insufficiency (J Endocr Soc, 2024).

Adrenal insufficiency is a real condition, and it is different. See adrenal fatigue.

What to check first

Because so many things cause tiredness, the usual first steps are a history and exam and some basic blood tests. Two that readers often ask about:

• Ferritin, a marker of the body’s iron stores. MedlinePlus lists weakness or fatigue among the symptoms of too little iron and of too much iron.
• TSH, a thyroid test. MedlinePlus lists fatigue among the symptoms of both an overactive and an underactive thyroid.

A cortisol test is one more possibility, usually when a clinician suspects a cortisol disorder because of the other symptoms above. A single result can’t diagnose or rule out adrenal insufficiency or Cushing’s syndrome. If you order your own tests, the results still need to go to a clinician. See tests for tiredness.

• TSHA common first check of the thyroid $39 See this test at HealthLabs
• Cortisol AM and PMA morning sample and a later one. Check the timing before you order $129 See this test at HealthLabs

Sold by HealthLabs. Prices checked November 2026. Not available in ND, RI, NY, NJ, MD and HI. We earn a commission on sales.

When to see a clinician

See a clinician if you have been tired for weeks, whatever the reason you suspect. Mention weight loss, loss of appetite, dizziness on standing, muscle weakness or any steroid medicine you take, because those are on the NIDDK lists for adrenal insufficiency and Cushing’s syndrome.

If you take a steroid medicine, don’t stop or change it. Ask your prescriber what to do if you become ill. NIDDK says people with adrenal insufficiency should talk with their doctor about how to adjust their corticosteroid dose during an illness.