How long does cortisol stay in your system?

Cortisol doesn’t linger in the blood for long. In the main study we found, cortisol given by vein to young people with a medical condition fell by half in roughly an hour or more, and the range between people was wide. That is not the same as how long its effects last, and it isn’t the same as how long a cortisol test takes.

This page answers each of those questions in turn.

What the studies measured

Researchers have estimated how fast cortisol leaves the circulation in a few ways. The figures aren’t identical, and each has limits.

• About 76 minutes on average, with a wide range. A 2015 study gave 48 young people with a condition called congenital adrenal hyperplasia a dose of hydrocortisone, the medicine form of cortisol, by vein, and tracked the blood level. The average half-life was 76.5 minutes. The range was 40 to 225 minutes (PubMed). The group was young and had a medical condition, and the cortisol was given as a medicine, so the figure is a guide and not a rule.
• A much shorter figure for free cortisol. A 2012 study of 21 healthy adults used a mathematical model on blood levels after an ACTH-like injection and estimated the half-life of free cortisol at about 2 minutes (PubMed). Free cortisol is the small part that isn’t attached to a carrier protein. The number comes from a model under test conditions, so don’t compare it directly with the first.
• Carrier proteins change the picture. A 2011 study gave hydrocortisone by vein and found that the half-life of total serum cortisol was longer in women taking oral contraceptives and shorter in people lacking a working carrier protein, called CBG. Free cortisol behaved normally in the people without CBG, though the women on the pill still had a longer half-life (PubMed). For more on free and total cortisol, see free vs total cortisol.

So the honest answer is “about an hour or so, depending on what is measured, who is measured and how”. Nobody can tell you your own half-life from a single blood test.

Why levels don’t just drain away

Cortisol isn’t a one-time dose that wears off. Your adrenal glands release it in pulses all day. A 2017 review describes pulses that come every 60 to 90 minutes, with larger pulses while you are awake and smaller ones in the early hours of sleep (Endocrine Reviews, 2017). On top of that sits the daily rise and fall. See when cortisol is highest.

For comparison, ACTH, the pituitary hormone that signals the adrenal glands, is even shorter-lived. A 2023 laboratory review gives its half-life in the body as about 6 to 7 minutes (Diagnostics, 2023).

What does this mean for the question “how long does it take cortisol levels to drop”? These studies measured cortisol given as a medicine or injected for testing, so they don’t tell you how long a stress-driven rise lasts. If a level looks wrong for the time of day, finding the reason is a job for a clinician. MedlinePlus says abnormal results can come from stress, pregnancy, exercise, temperature extremes and medicines, and that more testing is usually needed to find a cause. A single blood cortisol can’t diagnose or rule out Cushing’s syndrome or adrenal insufficiency.

How cortisol leaves the body

The body uses a few routes.

• Conversion. Enzymes turn active cortisol into inactive cortisone, in places such as the kidney. See cortisone vs cortisol.
• Urine and saliva. MedlinePlus says some cortisol passes into the urine and saliva, which is why those fluids can be tested.

The word “leave” can mislead. The cortisol in your blood is replaced by new cortisol, as the pulses and the daily rhythm show. For the control system behind that, see the HPA axis.

Effects last longer than the molecule

Cortisol works by binding to receptors inside cells. A 2018 review says that this switches many genes on or off and that the effects are delayed and long-lasting, though it also describes some rapid effects at cell membranes (Front Behav Neurosci, 2018). So a hormone that clears from the blood in a few hours can still have effects that last longer.

Some tests take a longer view. A 2024 review says cortisol in scalp hair may give a longer-term view of cortisol status, but that it remains to be validated outside a research setting and is affected by factors such as sex, ethnicity, physical activity, light exposure and medicines. See saliva, urine and hair tests.

If you take a steroid medicine

How long a prescribed steroid medicine acts is a question for your prescriber or pharmacist. It is not the same as cortisol’s half-life. Don’t stop it, skip it or change the dose to “clear” it. NIDDK says suddenly stopping corticosteroids after taking them for a long time is the most common cause of adrenal insufficiency.

How long does a cortisol test take?

These are the figures MedlinePlus and NIDDK give.

• Blood draw. Usually less than five minutes. Samples are often taken twice in a day, once in the morning when cortisol is highest and again around 4 p.m. The seller’s page for its morning-and-later test is unclear about when the second sample is taken and doesn’t say whether it is one visit or two. Check this before you order, and follow the timing on your lab order.
• Saliva. Many kits use a swab held in the mouth for about 2 minutes. You shouldn’t eat, drink, brush or floss for 30 minutes beforehand, and a provider may ask for several samples at different times.
• 24-hour urine. You collect all urine for 24 hours.
• Dexamethasone suppression test. You take a low dose at around 11 p.m. and blood is drawn the next morning, usually around 8 a.m. A clinician arranges this.

How long do cortisol test results take?

It depends on the test and the lab. MedlinePlus says that for self-collection tests, how long it takes to get results can vary with the type of test. We don’t state a turnaround time for any test on this page. The seller’s page for each test, and your order confirmation, show the timing that applies. If your results are slow, ask the seller or the lab.

Keep reading

• When is cortisol highest?

  The daily rhythm of cortisol.

• AM and PM timing

  When blood samples are taken and why.

• The HPA axis

  How the brain controls cortisol.

• Saliva, urine and hair tests

  What each sample type can and can't show.