At-home cortisol tests: every option, what each tells you and the pitfalls

You can test your cortisol at home in five ways: a hair sample, a finger-prick blood sample, saliva tubes, a 24-hour urine collection or dried urine strips. Each sends a sample to a laboratory, but they measure very different spans of time. A hair sample gives your average over roughly the past three months,¹ while blood shows one moment, saliva a few moments in one day, and urine one day. For the common question, "has my cortisol been out of balance?", a hair test is the most accurate measure of long-term cortisol from a single sample. No home test diagnoses or rules out a medical condition.

The five kinds of home cortisol test

• Hair. You cut a small lock of hair close to the scalp at the back of the head and post it. Hair grows about 1 cm a month, so the 3 cm nearest the scalp give an average over roughly three months.¹ There are no timing rules.
• Finger-prick blood. You prick a finger and collect a few drops of blood, usually before 10am, and the laboratory measures total cortisol at that moment. Some kits offer a venous draw at a clinic or by a visiting nurse for an extra fee.²³
• Saliva. You collect saliva into tubes at set times, typically four across one day from waking to bedtime, to show the daily curve of free cortisol.⁴ Some tests use a single sample.⁵
• 24-hour urine. You collect all your urine for a full day, and the laboratory measures the free cortisol passed in it. In the US, one is sold direct, with the collection handled through a patient service centre.⁶
• Dried urine. You wet filter-paper strips at four points over a day, and the laboratory measures cortisol, cortisone and their breakdown products.⁷ The main version sold is the DUTCH test, a Precision Analytical product.⁸

Each measures something real, but only hair covers more than a day. Our which cortisol test? tool helps match a test to your question, and cortisol tests compared sets them side by side.

Do you need a doctor to order one?

Not in the UK. Home cortisol kits are sold direct, and the blood tests from major UK providers come with a doctor's report or comment on the result.²³ In the US, a physician working with the company usually authorises the order. One provider adds a $6 physician service fee, another has a healthcare provider approve each request online, and some tests are not sold in every state.⁹¹⁰

A doctor's comment on a home result is not a diagnosis. If a result is outside the laboratory's range, or you have symptoms, the next step is your GP, who can arrange cortisol tests of blood, urine or saliva.¹¹ Our guide to getting a cortisol test from your doctor explains how that works.

Timing: the biggest pitfall for blood and saliva

Cortisol peaks at about 8.30am and falls to its lowest point around midnight, with smaller pulses every one to two hours.¹²¹³ A blood or saliva result only makes sense against a range written for the time it was taken: one NHS laboratory states that a random blood cortisol taken away from 9am cannot be interpreted.¹⁴ So follow the kit's timing exactly. Blood kits ask for the sample before 10am, and saliva kits ask for set times, with no food, drink or tooth-brushing for a period beforehand.²³⁴

If your kit includes a waking sample, take it on time. The cortisol awakening response, the sharp rise over the first 30 to 45 minutes after waking, depends on sampling from the moment you wake.¹⁵ Shift workers face a harder problem. NICE advises specialist advice before testing them, because it is uncertain when to test,¹⁶ and late-night saliva is not appropriate for people who work nights or have variable bedtimes.¹⁷ Hair is the exception: hair cortisol does not vary with the time of day it is cut.¹⁸

Medicines that can change the result

• Steroid medicines. Tablets, inhalers, nasal sprays, creams and injections can all matter. People using inhaled, injected or skin steroids at physiological doses or above may have a low morning blood cortisol, and NICE advises waiting four weeks after a steroid injection into a muscle or joint before testing.¹⁹ Some blood tests cross-react with prednisolone,¹³ and steroid creams or gels that get into a saliva tube can give a falsely high result.¹⁷ In hair, steroid medicines can raise or lower the result, depending on the drug.²⁰²¹ Never stop a steroid medicine to take a test: stopping suddenly is itself a common cause of abnormal cortisol levels.²² Tell the laboratory what you use.
• Oral oestrogen. The combined pill and some HRT raise the protein that carries cortisol in the blood. In one study, women on oral oestrogen had 67 per cent higher total blood cortisol, while their saliva cortisol was similar to that of women not taking it.²³ Saliva and urine measure free cortisol and are not affected in this way,¹³ and hair studies of the pill have found at most a small and inconsistent effect.²⁴ A home blood result taken while on oral oestrogen may read falsely high.
• Biotin. Some blood tests ask you to avoid biotin supplements for two to three days beforehand.²¹⁰

The day itself: stress, exercise and other surprises

Blood, saliva and urine also respond to whatever is happening that day. Psychological stress raises cortisol, most of all when a situation feels uncontrollable or you feel judged.²⁵ In one study, 30 minutes of exercise raised cortisol by about 40 per cent at moderate-to-hard intensity and 83 per cent at hard intensity.²⁶

That is why one day's result says a lot about that day. About 75 per cent of the variation in a single saliva sample reflects the situation on the day,²⁷ and researchers estimate that you need saliva from at least three separate days for a reliable average.²⁸ Even a full 24-hour urine collection varied by about 52 per cent from one collection to the next in people with Cushing's disease.²⁹ By contrast, hair cortisol correlated at r = 0.84 from one month to the next in the same people,³⁰ because one stressful day is a tiny part of the months a hair sample covers. If you use a snapshot test, take it on an ordinary day and treat a single result with caution.

What to watch for with a hair kit

Hair has its own pitfalls. People who dye their hair have had somewhat lower hair cortisol, by 12.5 per cent in one large study, and long exposure to sunlight lowers it too.²¹³¹ Hair grows at 0.6 to 1.4 cm a month depending on the person, so a 3 cm sample covers roughly two to five months,¹ and because new hair takes a few weeks to emerge, the most recent weeks before the cut are not included.³² Tell the laboratory about hair treatments and medicines. Our guides to taking a hair sample and testing dyed or treated hair explain more.

Home cortisol tests from major providers

The table lists blood, saliva, urine and dried urine tests from major UK and US providers, with prices as of October 2026. For what they cost overall, including clinic and physician fees, see what a cortisol test costs.

When to see a doctor instead

A home test is a way to learn about your cortisol, not a way to diagnose or rule out disease. See a doctor rather than relying on a home test if you have:

• signs that could mean too much cortisol, such as more fat on the neck, upper back and tummy with thinner arms and legs, a red round face, easy bruising, stretch marks or weakness at the tops of the arms and legs¹¹
• signs that could mean too little, such as extreme tiredness, weight loss, patches of darker skin, salt craving or dizziness on standing³³
• long-term steroid treatment: at least 1 per cent of people take steroid medicines long term, and they are at risk of steroid-induced adrenal insufficiency³⁴

If someone with known or suspected adrenal insufficiency suddenly gets worse, with severe dizziness, vomiting, confusion, drowsiness or loss of consciousness, call 999 (911 in the US).³³ And if you have been told you have "adrenal fatigue", the Endocrine Society says it is not a recognised condition and that no test can detect it.³⁵ See our guides to high cortisol symptoms and low cortisol symptoms.