At some point in the last two years, cortisol became the thing everything is blamed on. Cortisol face. Cortisol belly. Detox drinks that promise to flush it. Adrenal support capsules for the fatigue that will not lift. It has become the single hormone the internet has heard of, and it is being asked to explain far more than it can.
The underlying worry is real. People are exhausted, sleeping badly, gaining weight around the middle and not feeling like themselves. That deserves a better answer than the one being sold.
Cortisol has a daily rhythm
Schematic of the normal pattern. A single cortisol reading without knowing where you are on this curve tells you very little.
What cortisol is actually for
What cortisol actually does
Cortisol is not a stress toxin. It is the hormone that gets you out of bed. Levels rise sharply in the half hour after you wake, fall across the day, and bottom out around midnight. That rhythm is what makes you alert in the morning and sleepy at night.
It also releases stored glucose so your brain has fuel between meals, keeps blood pressure where it should be, and restrains inflammation. It is one of the reasons a steroid tablet is what a doctor reaches for in a severe asthma attack — that is cortisol’s pharmacological cousin doing its day job, turned up.
People who genuinely cannot produce enough of it have Addison’s disease, and they are seriously unwell. Cortisol is not something to be flushed out. It is something to have in the right amount, at the right time of day.
“Adrenal fatigue” is not a diagnosis
The idea is that prolonged stress wears the adrenal glands out until they can no longer keep up, leaving you tired, foggy and salt-craving. It is an intuitive story and it sells a great many supplements.
It has been looked for properly. A 2016 systematic review in BMC Endocrine Disorders assessed the entire published literature on adrenal fatigue and concluded there was no substantiation for it — the studies were methodologically inconsistent, used tests that were not validated for the purpose, and did not show the thing they claimed to show. No endocrine society recognises the condition.
What does exist, and is worth ruling out if your symptoms are persistent, is the real end of this spectrum: Addison’s disease, and Cushing’s syndrome at the other extreme. Both are uncommon, both are diagnosable with proper testing, and neither is managed with a herbal capsule.
This matters practically. If you are exhausted and you buy adrenal support, you have paid money for a bottle and, more expensively, spent six months not looking for the actual cause.
The claim, and the evidence
“Adrenal fatigue”
- The claim: prolonged stress wears the adrenal glands out until they can no longer keep up, leaving you tired, foggy and salt-craving
- A 2016 systematic review in BMC Endocrine Disorders assessed the entire published literature and concluded it does not exist
- It is not a recognised diagnosis
What is real
- Addison’s disease — a genuine inability to produce enough cortisol. Those affected are seriously unwell
- Cushing’s syndrome — the opposite end of the same axis
- Both are diagnosable and treatable, and worth ruling out if your symptoms are persistent
What chronic stress genuinely does to a body
None of the above means stress is harmless. It means the mechanism is not a cortisol reservoir filling up.
Sustained stress interferes with sleep, and short sleep measurably reduces insulin sensitivity within days in healthy people. It changes what you eat and when — more in the evening, more refined carbohydrate, more alcohol. It raises blood pressure. It makes people abandon exercise at exactly the point they would benefit most. Over years, that combination shows up as abdominal fat, worse glycaemic control and higher cardiovascular risk.
The damage is real. It just arrives through sleep, food, movement and blood pressure rather than through a hormone accumulating somewhere.
What does not work
Cortisol detox drinks. There is nothing to detoxify. Your cortisol is cleared by your liver on a schedule your adrenal glands and pituitary control between them.
Salivary cortisol panels sold direct to consumers. Four spit samples and a colour-coded chart is not how an endocrinologist investigates the adrenal axis, and the interpretation you get back is usually built to sell you the accompanying protocol.
“Adrenal support” glandulars. Bovine adrenal extract, sold on a theory that does not hold, with no dosing standard.
Ashwagandha, if you expect it to be the answer. This one deserves a fairer hearing than the rest. Meta-analyses of randomised trials do find modest reductions in perceived stress and anxiety scores, and in measured cortisol, against placebo. The trials are small, mostly short, and often industry-funded, and results across reviews are not consistent. It is a reasonable thing to try and a poor thing to rely on. It is also not free of risk: there are case reports of liver injury, it is not recommended in pregnancy, and it can interact with thyroid medication and sedatives. If you take a prescription medicine, ask your pharmacist before you add it.
Tired for months and being told it is just stress? Send me your reports. Half the time the answer is sitting in bloodwork nobody read properly.
Sold for cortisol — and where the evidence is
| What is sold | Where the evidence actually is |
|---|---|
| Cortisol detox drinks | There is nothing to detoxify. Cortisol is cleared by your liver on a schedule your adrenal glands and pituitary control between them |
| Direct-to-consumer salivary cortisol panels | Four spit samples and a colour-coded chart is not how an endocrinologist investigates the adrenal axis |
| “Adrenal support” glandulars | Bovine adrenal extract, sold on a theory that does not hold, with no dosing standard |
| Ashwagandha | The fairest of the four. Meta-analyses of randomised trials do find modest reductions in perceived stress and anxiety scores — but it is not the answer on its own |
What actually moves the physiology
Sleep, before anything else. It is the lever with the largest effect and the one people trade away first. Seven hours is not indulgence; it is the intervention. A consistent wake time does more for the cortisol rhythm than any supplement aimed at it.
Exercise, at a sensible dose. Regular activity lowers resting stress physiology and improves sleep quality. Two hard sessions on four hours of sleep does the opposite, so if you are already depleted, walking and resistance training beat punishing cardio.
Slow breathing. Unglamorous, free, and better supported than most of what is sold on this topic. Five or six breaths a minute for ten minutes shifts you measurably towards the parasympathetic side. It is not a cure for a difficult life, but it is a real physiological handle.
Caffeine and alcohol timing. Caffeine has a half-life of around five hours, so an evening coffee is still working at bedtime. Alcohol gets you to sleep faster and fragments the second half of the night. Both are commonly the actual reason someone is exhausted and blaming their adrenals.
Other people. Loneliness is a physiological stressor, not just an unpleasant feeling, and it is one of the few things on this list that no product addresses.
And the unfashionable one: where you can change the stressor, change the stressor. A great deal of wellness advice exists to help people tolerate situations that should not be tolerated indefinitely.
When it is not stress at all
“It is just stress” is the most over-prescribed explanation in medicine, and it is worth being sceptical of when the tiredness has lasted months. Things that impersonate it, and are all straightforward to test for:
- Hypothyroidism — fatigue, weight gain, cold intolerance, low mood
- Iron deficiency — exhaustion and breathlessness, often with a normal haemoglobin and an empty ferritin
- Vitamin B12 deficiency — fatigue, brain fog, tingling; common in vegetarians and on long-term metformin
- Vitamin D deficiency — near-universal in urban India and cheap to correct
- Obstructive sleep apnoea — the single most missed cause of unrefreshing sleep, particularly with snoring or a thicker neck
- Undiagnosed diabetes — fatigue is an early and unremarkable-sounding symptom
- Depression and anxiety disorders — which are medical conditions with effective treatment, not a failure of resilience
If low mood, loss of interest or persistent anxiety have been present most days for weeks, that is worth taking to a doctor or a mental health professional rather than to a supplement shelf. It responds to treatment, and it responds better the earlier it is addressed.
When it is not stress at all
| Cause | How it presents |
|---|---|
| Hypothyroidism | Fatigue, weight gain, cold intolerance, low mood |
| Iron deficiency | Exhaustion and breathlessness, often with a normal haemoglobin and an empty ferritin |
| Vitamin B12 deficiency | Fatigue, brain fog, tingling. Common in vegetarians and on long-term metformin |
| Vitamin D deficiency | Near-universal in urban India, and cheap to correct |
| Obstructive sleep apnoea | The single most missed cause of unrefreshing sleep, particularly with snoring or a thicker neck |
| Undiagnosed diabetes | Fatigue is an early and unremarkable-sounding symptom |
| Depression and anxiety disorders | Medical conditions with effective treatment — not a failure of resilience |
Every one of these is findable on ordinary bloodwork or a straightforward referral, and every one of them gets missed when the answer is assumed to be stress.
What I will not tell you
That your cortisol is high. I do not know that, you probably do not know that, and a face in a mirror is not a measurement.
That stress is not doing you harm. It is. The route is through your sleep, your plate, your blood pressure and the exercise you stopped doing.
That a supplement will fix a life that is genuinely too full. Nothing in a capsule outperforms an hour more sleep and one fewer obligation.
The short version
- Cortisol is an essential hormone with a daily rhythm, not a toxin to be flushed
- “Adrenal fatigue” has been systematically reviewed and is not a recognised diagnosis; Addison’s and Cushing’s are real and testable
- Chronic stress harms you through sleep, appetite, blood pressure and inactivity — which is where the fixes live
- Detox drinks, direct-to-consumer saliva panels and adrenal glandulars have nothing behind them
- Ashwagandha has modest, inconsistent trial support and real interactions — worth trying, not worth relying on
- Months of fatigue deserve thyroid, ferritin, B12, vitamin D, glucose and a sleep apnoea question before it is written off as stress
Before you act on any of this
I am a pharmacist and a nutritionist. I am not your doctor, and this article is general information rather than advice about you specifically. Nothing here is a reason to start, stop or change a prescribed medicine, including any supplement you are already taking on medical advice. If you are persistently exhausted, low, or anxious, that is worth a proper consultation rather than a purchase. What this article can do is tell you which questions are worth asking at your next appointment.
Sources
- Adrenal fatigue does not exist: a systematic review (BMC Endocrine Disorders, 2016)
- Does Ashwagandha supplementation have a beneficial effect on the management of anxiety and stress? A systematic review and meta-analysis of randomized controlled trials
- Ashwagandha: Is it helpful for stress, anxiety, or sleep? (NIH Office of Dietary Supplements)
