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The Cortisol Test That Measures Months, Not Moments
Tired all the time? Wired at night? Months of stress you can feel in your body? Testing your cortisol is the right instinct — but most cortisol tests can't answer the question you're actually asking.
Blood and saliva kits measure cortisol at a single moment, and cortisol changes hour by hour. Cortigenix measures your average cortisol over the past 3 months from one small hair sample, taken at home.
No blood. No needles.
Quick, easy at-home collection
Free UK postage
Single sample — no repeats needed
Clinically proven with expert support
Before you buy a cortisol test, know what each type can tell you
Sample method: Hair | Measurement window: 3 months
Cortisol isn't a fixed number. It peaks shortly after waking, falls through the day, and spikes with stress, exercise, poor sleep — even the journey to a clinic. That's why the type of test you choose matters more than the brand on the box.
Blood, saliva and urine tests capture cortisol at one point in time. In a clinical setting they're the right tool for investigating acute adrenal conditions — but as a picture of your everyday levels they're hostage to the moment: a calm morning can read “normal” after months of elevated cortisol, and one stressful commute can read “high” when nothing is wrong long-term.
A hair test works differently. As hair grows (about 1cm a month), cortisol from your bloodstream is locked into the hair shaft. Laboratory analysis of the 3cm closest to the scalp reveals your average cortisol over the past three months — unaffected by the time of day, how you slept, or how stressful the morning of the test happened to be. It's the same principle as an HbA1c test for blood sugar: sustained exposure, not a single reading.
If you're testing because of ongoing stress, fatigue, poor sleep or stubborn weight, the question isn't “where is my cortisol right now?” — it's “where has my cortisol been for months?” Only a hair test answers that.
Why one hair test beats a drawer full of snapshot kits
Single-moment kits can look cheaper — until you try to build a reliable picture with one. Because every result depends on the day and hour you took it, you'd need repeated samples across days or weeks just to approximate a trend, and you'd still never see your true average. One Cortigenix test gives you that average from a single collection — the kit, prepaid return postage, laboratory analysis and your personal results dashboard, all included in the single £126.75 price.
Signs your cortisol may be out of balance
Cortisol touches nearly every system in the body. When it stays too high — or too low — for months, people commonly report:
- Persistent fatigue that sleep doesn't fix
- Feeling “tired but wired” — exhausted all day, wide awake at night
- Difficulty sleeping or early waking
- Anxiety or feeling constantly on edge
- Low mood or emotional flatness
- Brain fog and difficulty concentrating
- Unexplained weight gain, particularly around the abdomen
- Strong cravings for sugary or salty foods
- A puffy or rounded face
- Recurrent infections or slow recovery
- Headaches
- Irregular periods
- Reduced libido
- Muscle or joint pains
- Digestive problems
Who should take this test?
- You've had symptoms for months but a one-off blood test came back “normal”
- You want to know whether stress is genuinely affecting your body — with data, not guesswork
- You're comparing cortisol test kits and want the one result that reflects your real, sustained levels
- You want a baseline before making lifestyle changes — and to re-test later to prove they're working
- You're trying to conceive and want to check whether stress hormones may be a factor
- You want objective evidence to bring to a GP appointment
Why hair testing gives a clearer picture
Blood, saliva and urine tests capture cortisol at a single moment. But cortisol fluctuates constantly — by the hour and by the day — meaning a result on a calm morning can look completely different to one taken during a stressful week. A single snapshot can lead to results that are misleading or missed altogether.
Hair cortisol testing works differently. As hair grows (~1cm per month), cortisol from your bloodstream is incorporated into the hair shaft. Analysing the section closest to the scalp gives a reliable, averaged picture of cortisol exposure over the past three months — unaffected by whether you had a bad night before the test, or exercised that morning.
It's the same principle as an HbA1c test for blood sugar: one measurement that reflects sustained exposure over time, not just today.
Hair vs other cortisol tests
Other cortisol tests only measure where your cortisol sits at a single moment. But cortisol changes minute by minute — which is why a one-off blood test can miss the full picture. Hair cortisol testing works like an HbA1c for blood sugar: it gives you a reliable average over three months, not just a snapshot of today.
| Feature | Hair test Cortigenix | Blood test | Saliva test | Urine test |
|---|---|---|---|---|
| Measures cortisol over 3 months | ✓ | ✗ | ✗ | ✗ |
| Single sample — no repeat testing needed | ✓ | ✗ | ✗ | ✗ |
| Unaffected by acute stress on test day | ✓ | ✗ | ✗ | ✗ |
| Detects chronic (long-term) cortisol patterns | ✓ | ✗ | ✗ | ✗ |
| No needles or clinic visit required | ✓ | ✗ | ✓ | ✓ |
| Suitable for at-home self-collection | ✓ | ✗ | ✓ | ✓ |
| Results unaffected by time of day | ✓ | ✗ | ✗ | ✗ |
| Validated by peer-reviewed research | ✓ | ✓ | ✓ | ✓ |
| Useful for diagnosing adrenal conditions | ✓ | ✓ | ✓ | ✗ |
As a busy professional, stress is a constant in my life. I suspected it was affecting my health, and this test confirmed it. Armed with knowledge about my cortisol levels, I've been able to make small changes to my routine that have had a big impact on my overall well-being. Dashboard is very detailed and informative.
S Dallaway
I've been struggling with fatigue and mood swings for ages, but doctors couldn't pinpoint the cause. After taking Cortigenix's Cortisol Test, I finally had answers. Turns out, my cortisol levels were out of whack. With targeted support and guidance, I'm feeling more like myself again.
M Perry
I wanted to take my health into my own hands and get a proper baseline reading rather than relying on GP appointments. The dashboard is detailed and actually gave me something to act on.
Mel
How it works
No clinic visit. No needles. Everything by post, all from home.
Step 1
Order your test kit
Step 2
Take a small hair sample at home
Step 3
Post your sample using the prepaid envelope
Step 4
Receive results in your secure portal within 10 days
Sample: A small hair sample from the back of your head — minimum 1cm in length, about 8–10 strands thick. Full instructions included in your kit.
Still have questions?
What is cortisol?
Cortisol is a hormone often called the 'stress hormone' because of its role in helping the body respond to stress. It regulates a wide range of functions: immune response, metabolism, reproductive health, blood pressure, and brain function. Every cell in the body has cortisol receptors, which is why prolonged imbalance — whether too high or too low — can affect so many aspects of your health.
Why measure cortisol over 3 months rather than with a single blood test?
Cortisol fluctuates constantly — it varies by the hour and can spike significantly on a stressful day. A single blood, saliva or urine test only captures a snapshot of one moment, which means a 'high' or 'low' result could simply reflect the circumstances of that morning.
Measuring cortisol in hair provides a reliable average over the past 3 months, in the same way an HbA1c test measures average blood sugar over 3 months rather than a single glucose reading. This makes it far more useful for assessing chronic stress, adrenal health, and long-term cortisol patterns.
Why does this test use hair rather than blood, saliva or urine?
Hair is a stable, long-term record of cortisol exposure. As hair grows (roughly 1cm per month), cortisol from the bloodstream becomes incorporated into the hair shaft. Analysing the section closest to the scalp gives a precise, averaged view of cortisol levels over the preceding three months.
Blood, saliva and urine tests are affected by acute stress, time of day, exercise, and medication taken before the test. Hair cortisol is not — making it a more objective and reproducible measure of your true long-term cortisol status.
What is the science behind Cortigenix's test?
Hair cortisol testing is backed by decades of peer-reviewed research and is used by scientists at institutions including the University of Oxford, King's College London, Harvard University, and the University of Auckland. Our test has been independently validated using data from thousands of participants. Research partners include the University of Nottingham, University of Auckland, and King's College London.
Is your test available worldwide?
Yes. We ship to over 170 countries. UK orders include free postage. International shipping rates are calculated at checkout.
How much hair do I need to provide?
You need a small sample from your head — a minimum of 1cm in length and approximately 8–10 strands thick (around 2–3mm). Full instructions are included in your kit.
Where should I take my sample from?
We recommend taking your sample from the back of your head, near the cranial bone (the bump you can feel at the base of your skull). This area tends to give the cleanest, most consistent results and the sample is not visible once taken.
Will hair dye or treatments affect my results?
No. All hair samples are thoroughly washed before analysis to remove external contaminants, including dyes, bleach, conditioner, and styling products. Your results will not be affected.
How are my results delivered?
Results are delivered to your secure personal dashboard within 10 working days of your sample arriving at our laboratory. You'll receive an email notification when they're ready. If your results are outside the normal range, one of our cortisol experts will be available to discuss next steps.