Adrenal fatigue: what the evidence says and what else could explain your symptoms

"Adrenal fatigue" is not a recognised medical condition. The term is used for a group of common symptoms, such as tiredness, trouble sleeping or getting up, and craving salt or sugar, that are said to come from adrenal glands worn out by long-term stress. The Endocrine Society, a professional body of hormone specialists, says there is no scientific proof that adrenal fatigue is real and that no test can detect it.¹ A systematic review of 58 studies reached the same conclusion.² The symptoms are real, though, and some have causes that can be found and treated, including a genuine shortage of cortisol. This guide explains the difference.

What people mean by adrenal fatigue

The idea is that months or years of mental, emotional or physical stress overwhelm the body, and that the adrenal glands, which release cortisol in response to stress, can no longer keep up with what the body needs. Supporters of the idea link it with:¹

• tiredness
• trouble falling asleep at night or waking up in the morning
• cravings for salt and sugar
• relying on stimulants such as caffeine to get through the day

These symptoms are common and non-specific. They occur in many illnesses and in ordinary busy lives.¹ That is part of the problem with the label: it offers one appealing explanation for symptoms that can have many causes, some of them serious.

What the evidence says

The Endocrine Society's position is plain. There is no scientific proof that adrenal fatigue is a real medical condition, no test can detect it, and the tests offered for it are not based on scientific evidence.¹

The most thorough look at the research is a systematic review published in 2016. Its authors screened 3,470 articles and found 58 that met their criteria, 33 in healthy people and 25 in people with symptoms. The results conflicted almost systematically from one study to the next, and many studies had weaknesses, such as differing designs and poor assessment of fatigue. The review concluded that there is no evidence that adrenal fatigue is an actual medical condition.²

That does not mean stress leaves no mark on cortisol. Chronic stress can change how the hormone system that controls cortisol behaves, in different directions in different people.³ But a stress-related shift in cortisol is not the same as glands that have "run out", and it is not a diagnosis. See cortisol and stress.

The Endocrine Society also warns about supplements sold for "adrenal health". Many have not been tested for safety, and some contain little or none of their listed ingredients while others contain too much. Taking adrenal hormones you do not need can make your own adrenal glands stop working, and they may stay inactive for months after you stop, which risks a life-threatening adrenal crisis.¹

Adrenal insufficiency: the real condition with similar symptoms

Adrenal insufficiency, a true shortage of cortisol, is a real and potentially dangerous condition. It is one of the conditions that the Endocrine Society says people told they have adrenal fatigue may actually have.¹ The primary form, Addison's disease, is caused by destruction of the adrenal cortex, and in Western countries about 90 per cent of cases are autoimmune. It is uncommon: about 9,000 people in the UK have a diagnosis, with about 320 new diagnoses a year.⁴ Adrenal insufficiency can also follow long-term steroid treatment. At least 1 per cent of the population takes glucocorticoid medicines long term and is at risk.⁵

The NHS lists these symptoms of Addison's disease: extreme tiredness, darker patches of skin, loss of appetite and weight loss, tummy pain, feeling sick, salt craving, dizziness on standing, muscle weakness and cramps, and anxiety and depression.⁶ Several overlap with the symptoms blamed on adrenal fatigue, which is exactly why they deserve proper testing.

Unlike adrenal fatigue, adrenal insufficiency can be measured. The first test is usually a blood cortisol taken between 8 and 9 am. NICE treats a result below 150 nmol/L as a reason to refer to a hormone specialist, 150 to 300 nmol/L as uncertain, and above 300 nmol/L as making adrenal insufficiency very unlikely.⁷ The diagnosis is confirmed with the short Synacthen (ACTH stimulation) test, the gold standard. Cortisol is measured before and 30 or 60 minutes after an injection of synthetic ACTH, and a peak below about 500 nmol/L indicates adrenal insufficiency, although the exact cut-off depends on the laboratory's assay.⁸ See testing for Addison's, the Synacthen test and low cortisol symptoms.

Other causes of the same symptoms

The Endocrine Society names depression and obstructive sleep apnoea, alongside adrenal insufficiency, as conditions that may lie behind the symptoms blamed on adrenal fatigue.¹ The NHS lists many causes of tiredness. They include lack of sleep, an unhealthy lifestyle, stress and depression, hormonal changes such as the menopause, and illnesses such as glandular fever and COVID-19, as well as iron deficiency anaemia, diabetes and an overactive thyroid.⁹

• Depression. Depression is a common cause of tiredness.⁹ There is no physical test for it. A GP diagnoses it by talking through your symptoms, health, history and circumstances, sometimes using a questionnaire, and may arrange blood or urine tests to rule out conditions with similar symptoms, such as an underactive thyroid.¹⁰ See cortisol, anxiety and depression.
• Obstructive sleep apnoea. The airway narrows during sleep, so breathing repeatedly stops and starts. Typical signs are loud snoring, gasping or choking noises at night, and feeling very tired during the day. If a GP suspects it, they can refer you to a sleep clinic, where you wear devices overnight, usually at home, that monitor your breathing and heart rate.¹¹ See cortisol and sleep.
• Anaemia, diabetes and thyroid problems. A GP can check for these with blood tests.⁹

Why no test can detect adrenal fatigue, hair included

A test needs something to detect. Adrenal fatigue has no agreed definition and no evidence that it exists, so there is no cortisol level, pattern or cut-off that could confirm it.¹² Blood and saliva tests are sometimes offered to "diagnose" it, but the Endocrine Society says these tests lack solid scientific support and that their results and interpretation may be wrong.¹

The same applies to hair. A hair test is the most accurate way to measure your long-term cortisol from a single sample, but it measures cortisol, not a condition. A lower-than-usual hair result does not mean your adrenal glands are "fatigued": lower hair cortisol has also been found, for example, in groups with anxiety disorders, including post-traumatic stress disorder.¹² Nor does a hair test diagnose or rule out adrenal insufficiency. Hair cortisol is still a research tool that needs validating outside research settings,¹³ and the Synacthen test remains the standard for diagnosis.⁸

If any cortisol result, from any kind of test, is outside its laboratory's range, the next step is a conversation with a doctor, not a supplement.

What to do if you feel exhausted all the time

The NHS advises seeing a GP if you have felt tired for a few weeks and do not know why, if tiredness affects your daily life, if it comes with other symptoms such as weight loss or mood changes, or if you have been told you make gasping, snorting or choking noises in your sleep.⁹ Tell the GP about any steroid medicines you use or have recently stopped, including inhalers, creams and injections, because long-term glucocorticoid treatment can leave the adrenal glands unable to make enough cortisol.⁵

The Endocrine Society's advice is not to accept an unproven diagnosis when you feel tired, weak or low, because finding the real cause is the key to feeling better. Whatever the cause turns out to be, it notes that giving up smoking, alcohol and drugs, being active, eating well and keeping a regular sleep and wake routine generally help.¹ If you are already being treated for adrenal insufficiency and become suddenly unwell, follow the emergency advice in the box above.