Overview
cortisol
The main human glucocorticoid, regulating stress response, glucose availability and inflammation on a daily rhythm.aldosterone
The adrenal hormone controlling sodium retention and potassium excretion, and therefore blood volume and pressure.cortisol
The main human glucocorticoid, regulating stress response, glucose availability and inflammation on a daily rhythm.Interesting facts
- • The adrenal medulla is essentially a modified sympathetic ganglion — nerve tissue that secretes into blood rather than across a synapse.
- • Cortisol follows a pronounced daily curve, and the sharp rise in the first hour after waking is distinct enough to be used as a research measure in its own right.
- • Adrenaline was among the first hormones ever isolated and is still on the WHO essential medicines list, unchanged in its core clinical role for over a century.
- • The adrenal cortex builds every one of its hormones from cholesterol, using a branching assembly line where a single enzyme deficiency redirects production down another path.
- • Aldosterone acts on the kidney to retain sodium, and dysregulation of this single hormone is one of the most common identifiable causes of high blood pressure.
Common misconceptions
- Chronic stress causes 'adrenal fatigue', where the glands become exhausted and stop producing cortisol.
Adrenal fatigue is not a recognised diagnosis and systematic reviews have found no consistent evidence that it exists. The fatigue is real; this particular explanation for it is not supported, and genuine adrenal insufficiency is a distinct, testable condition. - Cortisol is a harmful hormone to be minimised.
Cortisol is essential — it maintains blood pressure, blood glucose and the ability to respond to illness. Both excess and deficiency cause serious disease. The goal is a normal rhythm, not a low level. - Adrenal supplements support stressed adrenal glands.
Some over-the-counter 'adrenal support' products have been found to contain actual steroid or thyroid hormone, which can suppress your own function and cause real harm. - A salivary cortisol test can diagnose stress-related adrenal problems.
Late-night salivary cortisol has a genuine role in diagnosing Cushing's syndrome, but multi-point 'adrenal stress profiles' sold direct to consumers have not been validated for the purposes they are marketed for.
Anatomy & how it works
A layered cortex wrapped around a nervous-tissue core, with each cortical zone producing a different class of hormone.
Zona glomerulosa
The outermost cortical layer, producing aldosterone under the control of the kidney's renin-angiotensin system.
Zona fasciculata
The thick middle layer that produces cortisol in response to pituitary ACTH.
Zona reticularis
The innermost cortical layer, producing DHEA and other androgen precursors.
Adrenal medulla
The core of modified nerve cells releasing adrenaline and noradrenaline on sympathetic command.
Adrenal capsule
The fibrous outer shell, containing progenitor cells that renew the cortex throughout life.
Blood supply
An unusually rich arterial supply draining through a single central vein on each side, allowing hormones to reach circulation almost immediately.
Cortisol
The main human glucocorticoid, regulating stress response, glucose availability and inflammation on a daily rhythm.ACTH
Adrenocorticotropic hormone from the pituitary, the direct signal telling the adrenal cortex to make cortisol.cortisol
The main human glucocorticoid, regulating stress response, glucose availability and inflammation on a daily rhythm.cortisol
The main human glucocorticoid, regulating stress response, glucose availability and inflammation on a daily rhythm.Aldosterone
The adrenal hormone controlling sodium retention and potassium excretion, and therefore blood volume and pressure.cortisol
The main human glucocorticoid, regulating stress response, glucose availability and inflammation on a daily rhythm.aldosterone
The adrenal hormone controlling sodium retention and potassium excretion, and therefore blood volume and pressure.Primary functions
- • Producing cortisol to regulate the stress response, glucose availability and inflammation
- • Producing aldosterone to control sodium, potassium and blood pressure
- • Releasing adrenaline and noradrenaline for immediate fight-or-flight responses
Secondary functions
- • Supplying androgen precursors, the main source of androgens in women before menopause
- • Supporting blood pressure maintenance during illness, injury and blood loss
- • Modulating immune activity and the resolution of inflammation
Across a lifetime
- Development
- The fetal adrenal is proportionally enormous and produces the hormone precursors the placenta needs for oestrogen synthesis; a surge in fetal cortisol helps mature the lungs before birth.
- Childhood
- Congenital adrenal hyperplasia, an inherited enzyme defect in the cortisol pathway, is screened for in many newborn programmes because untreated salt-wasting forms can be fatal in the first weeks.
- Adulthood
- Adrenal insufficiency most often presents in adulthood, usually autoimmune in high-income countries; incidental adrenal nodules are found with increasing frequency as abdominal imaging becomes routine.
- Later life
- DHEA output falls steadily from the twenties onward while cortisol rhythm flattens somewhat with age, and the blood pressure consequences of aldosterone dysregulation become more apparent.
- Sex differences
- Adrenal androgens are the dominant androgen source in premenopausal women, so adrenal disorders affect hair growth, cycles and skin more visibly in women; autoimmune adrenal insufficiency is also somewhat more common in women.
Body connections
The adrenals are the body's emergency department and its salt-and-sugar accountant at once. Acutely, they make survival of injury, infection and blood loss possible; chronically, their output shapes blood pressure, body composition, bone density, glucose tolerance and immune tone. This dual role is why adrenal excess and deficiency both produce whole-body illness, and why exogenous steroids — among the most useful drugs in medicine — reproduce the harms of adrenal excess so faithfully.
Body connections
How this links to the rest of you
The glands sit directly on the kidneys and work with them through the renin-angiotensin-aldosterone system to control blood volume and pressure.
Pituitary ACTH is the direct driver of cortisol production, so pituitary disease causes secondary adrenal insufficiency.
The hypothalamus initiates the cortisol axis, and cortisol in turn acts on the hippocampus and prefrontal cortex, affecting memory, mood and threat appraisal.
Adrenaline sets heart rate and contractility in acute stress, while aldosterone excess drives sustained hypertension and cardiac remodelling.
Prolonged cortisol excess, whether from disease or steroid treatment, is a leading cause of secondary osteoporosis.
Cortisol suppresses inflammatory signalling — the basis of every steroid anti-inflammatory drug.
How lifestyle changes it
Exercise
Exercise raises cortisol acutely, which is a normal adaptive response; regular training improves the efficiency of the stress response rather than depleting it, though very high training loads without recovery can disturb the rhythm.
Nutrition
Adequate sodium matters in diagnosed adrenal insufficiency, where salt requirements genuinely rise. For everyone else, no diet meaningfully alters adrenal function.
Hydration
Aldosterone and fluid balance are directly linked, and people with adrenal insufficiency dehydrate and drop their blood pressure much faster than others during illness or heat.
Sleep
The cortisol rhythm is tightly coupled to the sleep-wake cycle; shift work and chronic short sleep flatten and shift the curve, which is one plausible route from disrupted sleep to metabolic disease.
Stress
Psychological stress activates the axis by design. Prolonged activation is associated with sustained higher cortisol exposure and its metabolic consequences — not with the glands running out.
Ageing
Adrenal androgen production declines markedly with age while cortisol output is largely preserved, shifting the balance of adrenal steroid output across the lifespan.
Environment
Long-term glucocorticoid medication — inhaled, oral, topical or injected — is the commonest cause of adrenal suppression worldwide, and stopping it abruptly is genuinely dangerous.
Genetics
Congenital adrenal hyperplasia, familial hyperaldosteronism and the autoimmune polyendocrine syndromes are all inherited, and autoimmune adrenal failure clusters with thyroid and type 1 diabetes.
Symptoms & conditions
Common symptoms
Common conditions
Rare conditions
- • Addison's disease
- • Cushing's syndrome
- • Phaeochromocytoma
- • Congenital adrenal hyperplasia
- • Adrenocortical carcinoma
- • Adrenal haemorrhage
Acute & chronic problems
- • Adrenal crisis triggered by infection, surgery or missed steroid doses
- • Adrenal haemorrhage after major trauma or severe sepsis
- • Hypertensive crisis from an unrecognised phaeochromocytoma
- • Primary adrenal insufficiency requiring lifelong replacement
- • Steroid-induced adrenal suppression
- • Primary aldosteronism as a treatable cause of resistant hypertension
- • Incidentally discovered adrenal nodules requiring assessment
Early warning signs
- • Increasing fatigue with dizziness on standing
- • Salt craving with unexplained weight loss
- • Darkening of skin creases, scars and gums
- • Blood pressure that stays high on three or more medications
- • Episodic headache with sweating and palpitations
Risk factors
- • Long-term glucocorticoid therapy of any route
- • Other autoimmune endocrine disease
- • Family history of adrenal or endocrine tumour syndromes
- • Untreated tuberculosis in high-prevalence settings
- • Anticoagulation, for adrenal haemorrhage risk
Protective factors
- • Steroid tapering rather than abrupt cessation
- • Carrying a steroid emergency card and knowing sick-day dose rules
- • Investigating resistant hypertension for aldosterone excess rather than adding a fourth drug
- • Regular monitoring for anyone on long-term steroids
Optimise & recover
Prevention
- • Never stop long-term steroid treatment abruptly — taper under medical guidance, however low the dose seems
- • If you take replacement steroids, learn sick-day rules and carry an emergency injection and card
- • Ask about aldosterone testing if your blood pressure needs three or more drugs to control
- • Treat marketing claims about 'adrenal support' supplements with real scepticism, particularly any that make you feel dramatically better
Recovery
- • After steroid withdrawal, recovery of the axis can take weeks to many months, and cover is needed for illness or surgery throughout
- • In diagnosed insufficiency, doubling the replacement dose during febrile illness prevents most crises
- • Rebuild strength and aerobic capacity gradually after a period of cortisol excess or deficiency, both of which waste muscle
Adrenal disease is managed medically, not through exercise or manual therapy. The rehabilitation that matters is reversing the collateral damage: cortisol excess causes proximal muscle wasting, bone loss and glucose intolerance, all of which respond to progressive resistance training, weight-bearing exercise and dietary change once the hormonal problem is controlled.
Movement library
- Beginner
Sit-to-stand practice
Targets the proximal thigh weakness that is characteristic of prolonged cortisol excess or steroid therapy.
- Beginner
Progressive lower-limb resistance work
Directly counters the proximal myopathy caused by cortisol excess and long-term steroid use.
- Intermediate
Weight-bearing and impact exercise
Protects bone density, which is a major concern with any prolonged glucocorticoid exposure.
- Beginner
Graded aerobic training
Rebuilds exercise tolerance after adrenal insufficiency is stabilised, starting well below previous capacity.
- Beginner
General mobility routine
Useful for maintaining function during periods of steroid-related weakness; no adrenal-specific stretch exists.
There is no adrenal-specific massage benefit, and claims that manual therapy over the lower back stimulates the adrenal glands have no physiological basis. Massage may help general stress symptoms, which is a separate and legitimate claim.
Habits worth building
- • Keep morning light exposure and wake times consistent to support a normal cortisol rhythm
- • If you are on replacement, take the larger dose on waking to mimic the natural morning peak
- • Tell every clinician, dentist and anaesthetist about steroid use before any procedure
Nutrition, devices & products
For healthy adrenal glands there is no special diet — no food supports or depletes them in any measurable way. Nutrition becomes genuinely important in diagnosed disease: primary adrenal insufficiency raises salt requirements because aldosterone is missing, while cortisol excess drives glucose intolerance and muscle loss, making protein adequacy and carbohydrate quality matter more than usual.
Foods to prioritise
- • Adequate sodium, specifically in diagnosed primary adrenal insufficiency
- • Sufficient protein to protect muscle during any period of cortisol excess or steroid treatment
- • Calcium and vitamin D for bone protection on long-term steroids
- • Regular meals, since cortisol deficiency impairs the ability to maintain blood glucose while fasting
Foods to limit
- • Liquorice in large or sustained amounts, which mimics aldosterone and raises blood pressure
- • Alcohol, which disturbs both sleep and the cortisol rhythm
- • Unregulated 'adrenal glandular' supplements, some of which have been found to contain active hormone
| Supplement | Evidence | Note |
|---|---|---|
| DHEA | Limited | Sometimes used in adrenal insufficiency for wellbeing and libido, with small and inconsistent trial effects; not indicated in people with normal adrenal function. |
| Vitamin D and calcium | Strong | Well established for preventing bone loss in anyone on long-term glucocorticoid therapy. |
| Ashwagandha | Emerging | Small trials report modest reductions in perceived stress and cortisol; effects on any clinical outcome are unproven and quality control varies. |
| Adrenal glandular extracts | Limited | No credible evidence of benefit, and documented cases of products containing undeclared active hormones causing harm. |
Devices & wearables
- • Home blood pressure monitors, central to managing both aldosterone excess and adrenal insufficiency
- • Medical alert bracelets and steroid emergency cards
- • Emergency hydrocortisone injection kits for diagnosed insufficiency
- • Heart rate and heart rate variability tracking, which reflects sympathetic tone though it cannot measure cortisol
Professional treatments
- • Short synacthen (ACTH stimulation) testing
- • Overnight dexamethasone suppression and late-night salivary cortisol testing
- • Aldosterone-to-renin ratio screening in hypertension
- • CT or MRI adrenal imaging and adrenal vein sampling
- • Adrenalectomy for functioning tumours
Educational mention only, not a recommendation: Hydrocortisone as physiological cortisol replacement, Fludrocortisone to replace aldosterone in primary insufficiency, Spironolactone and related drugs to block aldosterone excess, Metyrapone and similar agents to reduce cortisol production in Cushing's syndrome, Alpha and beta blockade before phaeochromocytoma surgery.
When to seek medical care
Persistent fatigue with dizziness on standing, unexplained weight loss, salt craving or darkening skin creases should prompt testing for adrenal insufficiency — it is diagnosable and treatable, and it is dangerous to miss. Resistant high blood pressure deserves screening for aldosterone excess before a fourth drug is added. Anyone already on steroid replacement who becomes unwell needs to increase their dose and seek help early rather than wait.
Seek care promptly if you notice
- • Collapse, vomiting and low blood pressure in anyone taking or recently stopping steroids
- • Progressive weakness with weight loss and darkening of skin creases or gums
- • Episodes of severe headache, sweating and palpitations with very high blood pressure
- • Confusion or drowsiness during illness in known adrenal insufficiency
- • Blood pressure that remains uncontrolled on three or more medications
Research & frequently asked questions
Current research
- Modified-release and pump-delivered hydrocortisone are being studied to reproduce the natural cortisol rhythm more faithfully than conventional tablets, with quality-of-life outcomes as the main endpoint.
1
BMC Endocrine Disorders · 2016
Adrenal fatigue does not exist: a systematic review
Systematic review of 58 studies examining cortisol measures against fatigue, finding no consistent relationship and concluding the concept is not supported by evidence.
- Primary aldosteronism is increasingly recognised as far more common than historically assumed, and research is focused on simplifying screening so it is not missed in routine hypertension care.
2
The Lancet · 2021
Adrenal insufficiency
Review of diagnosis and management, emphasising sick-day dosing, emergency preparedness and the persistent excess mortality associated with adrenal crisis.
Emerging therapies
- • Selective cortisol synthesis inhibitors for Cushing's syndrome
- • Targeted radionuclide therapy for metastatic phaeochromocytoma
- • Steroidogenic cell replacement and gene therapy approaches for congenital adrenal hyperplasia
Scientific controversies
- • Whether 'relative adrenal insufficiency' in critical illness is a real entity requiring steroid treatment has been debated through several large and partly conflicting trials.
- • The commercial adrenal fatigue industry continues to expand despite systematic reviews finding no supporting evidence, creating a persistent gap between marketing and science.
- • How aggressively to investigate the many adrenal nodules now found incidentally on imaging remains unsettled, with real risks of both overtreatment and missed functioning tumours.
Thomas Addison described progressive adrenal failure in 1855, giving the condition its name and establishing that a small gland's failure could kill. Cortisone was isolated in the 1930s and first given to a patient with rheumatoid arthritis in 1948, producing an effect so dramatic that it won a Nobel Prize within two years — and then, as long-term use spread, revealed the full clinical picture of cortisol excess from the other direction.
Frequently asked questions
Is adrenal fatigue a real diagnosis?
No. A systematic review of dozens of studies found no consistent evidence that the condition exists as described. The exhaustion people experience is real and worth investigating, but the explanation is usually elsewhere — sleep, mood, thyroid, anaemia or genuine adrenal insufficiency, which is a different and testable condition.
How do I know if I have genuine adrenal insufficiency?
It is diagnosed with blood tests — a morning cortisol and usually an ACTH stimulation test — not with symptom questionnaires or saliva panels. The typical picture is progressive fatigue, weight loss, low blood pressure, salt craving and sometimes darkening of skin creases.
Can I lower my cortisol naturally?
Regular sleep, consistent morning light, exercise and reducing chronic stressors all support a normal cortisol rhythm. That is different from lowering cortisol as such, which is not a goal worth having — you need it.
Why can't I just stop my steroid tablets?
Long-term steroids suppress your own cortisol production, and stopping suddenly leaves you unable to respond to stress or illness. That can cause an adrenal crisis, which is a medical emergency. Any withdrawal needs a taper.
Are cortisol saliva tests worth buying?
Late-night salivary cortisol is a legitimate test for suspected Cushing's syndrome when interpreted by a clinician. The multi-sample 'adrenal stress profiles' marketed directly to consumers have not been validated for diagnosing the things they claim to diagnose.
Does high cortisol cause belly fat?
Genuine cortisol excess does redistribute fat centrally, along with other distinctive features like easy bruising, purple stretch marks and proximal muscle weakness. Central weight gain on its own, without those features, is very rarely due to Cushing's syndrome.
Explore further
Keep exploring
Glossary
- Cortisol
- The main human glucocorticoid, regulating stress response, glucose availability and inflammation on a daily rhythm.
- Aldosterone
- The adrenal hormone controlling sodium retention and potassium excretion, and therefore blood volume and pressure.
- ACTH
- Adrenocorticotropic hormone from the pituitary, the direct signal telling the adrenal cortex to make cortisol.
- HPA axis
- The hypothalamic-pituitary-adrenal loop that controls cortisol release and its feedback.
- Addison's disease
- Primary adrenal insufficiency, in which the gland itself fails to produce cortisol and aldosterone.
- Cushing's syndrome
- The clinical picture of prolonged cortisol excess, from either disease or steroid treatment.
- Phaeochromocytoma
- A tumour of the adrenal medulla that releases adrenaline in surges, causing episodic hypertension.
Trusted organisations & further reading
- NHS — Addison's disease
- NHS — Cushing's syndrome
- Society for Endocrinology — You and Your Hormones
- Why Zebras Don't Get Ulcers — Robert Sapolsky. The definitive popular account of the stress response and what sustained cortisol exposure does to the body.
- The Hormone Handbook — Society for Endocrinology. Concise clinical reference covering adrenal testing and replacement in practical detail.
Medical disclaimer
This page is for general education and does not replace personalised medical advice. If you have concerning symptoms, or before starting a new supplement, medication or exercise programme, speak with a qualified healthcare professional.