Salivary cortisol test explained
- Updated
- 2026-09-30
- Every number with its source
What the salivary cortisol test shows
Cortisol is a hormone produced by the adrenal cortex. It helps the body respond to stress and regulates metabolism, blood pressure and the inflammatory response. Its production is controlled by the pituitary gland in the brain through adrenocorticotropic hormone (ACTH), and the amount in blood and saliva changes over the day in a clear rhythm — highest in the morning shortly after waking, lowest late in the evening.
The salivary cortisol test is considered a convenient non-invasive alternative to the cortisol blood test: the sample can be collected at home with a special kit, simply by moistening a swab with saliva. That is why it is often used to collect samples at several points (for example morning and evening) and to assess whether the normal daily rhythm is preserved. The test helps to diagnose conditions in which cortisol production is disturbed — both too much of it (Cushing's syndrome) and too little (Addison's disease, secondary adrenal insufficiency). A result always has to be assessed together with the time of day at which the sample was taken, because the ranges for morning and evening differ.
When the test is done
- When Cushing's syndrome is suspected — with rapid weight gain, a rounding face, easy bruising, purple stretch marks or muscle weakness
- When Addison's disease or secondary adrenal insufficiency is suspected — with persistent tiredness, muscle weakness, loss of appetite and weight, abdominal pain
- To assess whether the normal daily cortisol rhythm is preserved (a test with several samples during the day)
- In addition to a cortisol test in blood or urine, when a non-invasive sample taken at home is needed
- To monitor the course of treatment when a disorder of adrenal or pituitary function has already been diagnosed
How to prepare
- Do not eat, drink, brush your teeth or use dental floss for 30 minutes before the sample is taken
- Wash and dry your hands before taking the sample, and follow the kit's instructions on handling the swab exactly
- Your doctor will state the specific time of day, or several times, at which the sample has to be taken — this must be followed, because the reference range depends on the time of day
- If your doctor orders a late-night sample, the Endocrine Society guideline says to collect it on two different evenings in the last hour before midnight (23–24 h), and not to smoke on the collection day, because smoking and liquorice can falsely raise the result
Reference values and the time of day
There is no single universal number for cortisol in saliva: the general limits depend on the time of day at which the sample is taken and on the method the particular laboratory uses, so the exact interval is given by the laboratory on the result report, together with the sampling time. That is also why a doctor assesses the result together with the time of day and the symptoms, and why a test with several samples shows whether the daily rhythm is preserved rather than only a single value.
A raised result
A raised cortisol in saliva may indicate too much hormone production by the adrenal or the pituitary gland. The most common causes are the long-term use of steroid medicines, an ACTH-producing tumour (in the pituitary gland or elsewhere) or an adrenal tumour producing cortisol. The result has to be assessed together with the time of day and the symptoms, and discussed with a doctor.
- Long-term use of steroid (glucocorticoid) medicines
- An ACTH-producing tumour in the pituitary gland or elsewhere in the body
- An adrenal tumour producing too much cortisol
- Cushing's syndrome
Symptoms that can accompany a raised result
- Weight gain, especially around the waist, with thinner arms and legs
- A rounding face
- Easy bruising
- Purple stretch marks on the skin
- Muscle weakness
What to discuss with a doctor with a raised result
- An assessment of the daily cortisol rhythm — several samples at different times of day
- An ACTH test in blood, which helps to separate pituitary from adrenal causes
- Imaging tests (of the pituitary or the adrenal glands), if a tumour needs to be clarified
- Whether steroid medicines that could affect the result are being taken at the time
A low result
A low cortisol in saliva may indicate adrenal or pituitary insufficiency. The causes include autoimmune damage to the adrenal glands (Addison's disease), infections, impaired pituitary function or a brain injury. Symptoms often develop gradually, so the result has to be discussed with a doctor together with other tests.
- Autoimmune damage to the adrenal cortex (Addison's disease)
- Infections damaging the adrenal glands (for example tuberculosis, HIV)
- Impaired pituitary function (hypopituitarism)
- Traumatic brain injury
Symptoms that can accompany a low result
- Persistent tiredness
- Muscle weakness
- Loss of appetite
- Weight loss
- Abdominal pain
What to discuss with a doctor with a low result
- An ACTH test and, if needed, a stimulation test to clarify adrenal function
- An electrolyte (sodium, potassium) test in blood
- An assessment of pituitary function, if secondary insufficiency is suspected
- Whether steroid medicines that could have temporarily suppressed adrenal function were stopped
Related indicators
Related indicators: cortisol in blood, ACTH, DHEA-S, TSH, testosterone, and also how to read blood test results.
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Frequently asked questions
›What is the normal range for cortisol in saliva?
The general limits depend on the time of day at which the sample is taken and on the method the particular laboratory uses, so there is no single universal number — the exact interval is given by the laboratory on the result report, together with the time the sample was taken.
›How does the salivary cortisol test differ from the blood test?
A saliva sample can be collected at home in a non-invasive way, and it is convenient for a test with several points during the day, when the daily rhythm needs to be assessed. Blood is most often taken at a healthcare facility in the morning, when cortisol is at its highest.
›How do I prepare for a salivary cortisol test?
According to MedlinePlus, for 30 minutes before the sample is taken you should not eat, drink, brush your teeth or use dental floss; wash your hands before taking the sample and follow the kit's instructions exactly.
›Why is the cortisol test taken several times a day?
In a healthy person the amount of cortisol changes over the day — highest in the morning, lowest in the evening. A test with several samples helps to assess whether this daily rhythm is preserved, rather than only a single value.
›Which symptoms suggest that cortisol is worth testing?
Signs of raised cortisol are rapid weight gain, a rounding face, easy bruising and purple stretch marks. Signs of low cortisol are persistent tiredness, muscle weakness and loss of appetite and weight. These symptoms are worth discussing with a doctor.
›Can the salivary cortisol test be done at home?
Yes — according to MedlinePlus the test can be done in a doctor's office or at home with a special kit, collecting saliva with a swab according to the kit's instructions and at the time the doctor has indicated.
›What is a late-night salivary cortisol test?
In a healthy person cortisol is at its lowest late in the evening. The Endocrine Society guideline on diagnosing Cushing's syndrome lists late-night salivary cortisol as one of the first-line tests, with two measurements on different evenings, because cortisol release varies. The test may not suit shift workers or people with irregular sleeping hours.
›What can distort a salivary cortisol result?
MedlinePlus states that cortisol levels are affected by stress, exercise, pregnancy, birth control pills and other medicines, and long-term steroid use. The Endocrine Society guideline notes that smoking, chewing tobacco and liquorice can falsely raise a late-night cortisol result. It is worth telling your doctor about these before the test.
Sources
Related markers
This site is not an emergency service. If severe chest or head pain, breathlessness, confusion, difficulty speaking, heavy bleeding or another acute problem has come on suddenly — do not wait for tests, call 112.
This information is not a diagnosis and does not replace a consultation with a doctor. Reference ranges depend on the laboratory, your age and sex — always compare your result with the range printed on your own report.