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Cortisol is not causing your symptoms, experts say
Cortisol is a stress hormone made by the adrenal glands — essential for normal function, with levels that naturally rise and fall throughout the day. Australian specialists say spikes in healthy people are not harmful. When chronic stress is linked to health problems, the problem is the chronic stress itself, not the cortisol level. Sustained elevation from conditions like Cushing's syndrome can cause osteoporosis, hypertension and diabetes — but this is rare. For people without such conditions, the evidence linking higher cortisol to ill health is 'not very strong'. Smartwatch stress readings do not measure cortisol.
Cortisol has become one of the most blamed hormones in wellness content — accused of driving weight gain, disrupted sleep and vague fatigue. Two Australian experts told ABC Health the picture is considerably more complicated — and more reassuring — than the social media version.
Associate Professor Theresa Larkin, a cortisol researcher at the University of Wollongong, describes the hormone as “essential for life.” Professor Ann McCormack, endocrinologist at St Vincent’s Hospital Sydney, says its primary job is ensuring enough glucose to stay mentally and physically alert — but it also regulates blood pressure, immune function, and cognitive and emotional processing.
What the cortisol spike narrative gets wrong
Cortisol levels change constantly across the day. They rise when you need to be alert, fall when you don’t, and spike acutely in response to any perceived stressor — crossing a road quickly, preparing for a difficult conversation, encountering something unexpected. These spikes are not dysfunction; they are the system working correctly.
McCormack is direct about the social media framing: “Cortisol spikes are not something healthy people need to fear.” She notes the growing volume of wellness content warning against coffee on an empty stomach or certain exercises for cortisol management — advice that is not supported by evidence.
Larkin makes the more important attribution point. When chronic stress does contribute to health problems, “the problem is the stress” — not the cortisol level as an independent variable. She says the hormone is “being blamed for so many things, but chronic stress is the cause, which needs to be addressed.”
When cortisol genuinely does cause harm
There are conditions where sustained cortisol elevation is clinically significant. Cushing’s syndrome — caused by a tumour that drives excess cortisol production — can cause osteoporosis, hypertension, diabetes and weight gain. McCormack is careful to note this is rare. For most people, without an underlying condition producing chronically elevated cortisol, the clinical evidence linking higher levels to harm is “not very strong.”
The implication for general practice is worth naming: patients presenting with unexplained weight change, muscle weakness or vague systemic symptoms and asking about cortisol are not asking an unreasonable question — they are responding to a real signal that something is not right. But a cortisol number, absent clinical context suggesting a disorder, is usually not what answers that question.
The testing question
Cortisol is not routinely measured because it requires specialised testing — urine, saliva or blood, interpreted against time-of-day norms and clinical presentation. The smartwatch “stress” scores patients sometimes cite are not cortisol readings. McCormack is clear: anyone genuinely concerned should see a doctor for formal assessment. “There are rare conditions where it needs to be dealt with or worked up properly.”
2 cents: reclaim the stress conversation
When a patient arrives with a screenshot about lowering their cortisol through seed cycling or cold plunges, the clinical response is not to dismiss the concern — the concern is real, even if the mechanism is wrong.
What they are usually describing is chronic stress and its downstream effects: disrupted sleep, weight changes, mood disruption, depleted energy. That is worth taking seriously and addressing directly. What is not useful is building a care plan around optimising a number that is not routinely testable, not a reliable biomarker for most of what patients are experiencing, and not independently modifiable by the interventions being sold to them.
Larkin’s reframe is the right clinical handle: “Understand that what we need to address are the causes of stress.” That conversation — identifying stressors, naming them, and working with the patient on what can actually change — has more clinical yield than any discussion of cortisol levels in a person without a diagnosable adrenal disorder.
Verdict: yes — a clinically useful counter to a wellness narrative that generates confusion in general practice consultations, backed by two Australian specialists.
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Frequently asked questions
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Should I test my cortisol levels?
Cortisol testing is not routine and requires specialised testing — urine, saliva or blood — interpreted in clinical context. Smartwatch 'stress' scores are not cortisol readings. If you are concerned about symptoms that might indicate a cortisol disorder (unusual weight gain around the face and trunk, easy bruising, muscle weakness), speak to your GP for assessment.
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Do I need to avoid coffee or certain exercises to prevent cortisol spikes?
No. Endocrinologist Professor Ann McCormack of St Vincent's Hospital says 'cortisol spikes are not something healthy people need to fear.' Social media advice warning against coffee on an empty stomach or specific exercises for cortisol management is not supported by evidence.