What Is Cortisol?

A key stress hormone and what it does

Cortisol is the main stress hormone in your body. In your brain, cortisol helps control your mood. It’s also involved in fear and motivation.

Cortisol plays many other roles as well. This article will detail the many functions of cortisol, how it’s made, medical conditions associated with it, how levels are tested, and more.

Graphic shows how the stress response system works starting with the hypothalamus and ending with cortisol release.

ttsz / Getty Images

What Is Cortisol?

Cortisol is a naturally occurring steroid. It’s made by your adrenal glands. How this compound is used throughout your body is controlled by the: 

  • Hypothalamus: A brain region that coordinates autonomic functions (such as hormone regulation and temperature control) and emotional activity
  • Pituitary gland: The “master gland.” A pea-size gland connected to the hypothalamus. It produces hormones that control many functions in your body.
  • Adrenal glands: Small triangular glands that sit atop your kidneys. They produce hormones that regulate stress, metabolism, blood pressure, immunity, and more.

These three structures together are called the hypothalamus-pituitary-adrenal axis (HPA axis).

Most of the cells in your body have cortisol receptors. That means cortisol has body-wide effects.

What Are Cell Receptors?

Cell receptors are proteins on the surface of a cell or inside a cell. They receive chemical messages that control cellular activity. It’s through receptors that hormones like cortisol are able to regulate and change processes in your body such as metabolism and the immune response. The cell’s response to cortisol varies with the type of cell.

What Is the Function of Cortisol?

Cortisol is a crucial hormone for many functions. It’s involved in:

  • Metabolism/blood sugar levels
  • Lowering inflammation
  • Memory formation
  • Salt and water balance
  • Blood pressure
  • Fetal development

Cortisol levels fluctuate during the day. In general, they’re high when you wake up and drop throughout the day. 

When you deal with stress, your body releases extra cortisol to get you through it. This is called the acute stress response or "fight-or-flight" response.

Fight-or-Flight Response

The fight-or-flight response is the reason cortisol is called the stress hormone. The response happens when something appears to threaten you in some way.

Basically, this response gives you the necessary physical resources to either fight your way out of a dangerous situation or get away from it. It’s a chain reaction that happens almost instantaneously.

What happens is:

  • You feel fear or stress.
  • The body's sympathetic nervous system (the system responsible for the fight-or-flight response) tells the adrenal glands to release the hormones epinephrine (adrenaline) and norepinephrine.
  • Epinephrine and norepinephrine immediately increase your heart rate, blood flow to the muscles, and reaction speed.
  • If the threat continues, the HPA axis prompts the pituitary gland to secrete adrenocorticotropin hormone (ACTH). This hormone works to increase the amount of cortisol in your blood. 
  • Cortisol prompts cells to release sugar (glucose) into your blood to provide fuel for your brain and muscles so they can continue dealing with the stressful situation.

During the high-stress situation, the body also shuts down autonomic functions to conserve energy. That makes more resources available for your body to use. For example, it may slow down digestion or pause your immune system.

As the threat passes, cortisol then helps the body return to its natural state.

Recap

Cortisol is a hormone that regulates stress, metabolism, the "fight-or-flight" response, and many other important functions. It's made by the adrenal glands. Levels and usage are regulated by the hypothalamus, pituitary, and adrenals (HPA axis).

Associated Conditions: High Cortisol

Your body functions best when cortisol is at optimal levels. Both high and low cortisol levels are tied to medical conditions.

High cortisol levels may be a sign of Cushing’s syndrome, or an effect of chronic stress, which can have other health consequences.

Chronic Stress

Chronic stress can lead to high cortisol levels. That can have a negative impact on your health.

The stress can come from a difficult ongoing situation, such as a job or caring for a sick loved one. It can also come from excessive worry.

This keeps the body in a high-alert state. That makes you over-respond to added stressors that you encounter throughout the day. Maybe a small delay in your busy schedule sends your anxiety into overdrive.

Symptoms of chronic stress include:

  • Headache
  • Digestive problems
  • Low sex drive
  • Overeating or under-eating
  • Anxiety symptoms

When the chronic stress continues long-term, it can lead to:

Chronic stress, cortisol levels, and mental disorders like depression and anxiety have a well-established link. So far, though, experts don’t have a good understanding of the link.

If you’re diagnosed with chronic stress, your healthcare provider may recommend:

You may also benefit from lifestyle changes that help alleviate your stress, such as exercising and meditation, or making life changes that reduce stress, such as switching jobs or eliminating unnecessary obligations.

Cushing’s Syndrome

A rare disease called Cushing’s syndrome can result from prolonged high cortisol levels. Usually, the levels are elevated due to a tumor that produces ACTH or taking corticosteroid drugs (synthetic forms of cortisol).

Symptoms of Cushing’s syndrome include:

  • Acne
  • Fat deposits on the back of the neck (called a buffalo hump)
  • High blood sugar levels
  • Fatigue
  • Excessive hair growth
  • Menstrual changes
  • Rapid weight gain that’s mainly in the face and torso
  • A flushed, round face
  • High blood pressure
  • Easy bruising
  • Purple stretch marks on the skin
  • Muscle weakness
  • Anxiety, depression, or irritability
  • Increased thirst
  • Frequent urination

Tumors of the pituitary gland that lead to Cushing’s are typically not cancerous, but tumors that develop outside of the pituitary gland (in the pancreas, thyroid, or thymus glands) may be cancerous.

Treatments for tumor-related Cushing’s are:

  • Surgery to remove the tumor and possibly the gland it’s on
  • Radiation to shrink the tumor, if surgery isn’t possible
  • Medications including Signifor (pasireotide) and Korlym (mifepristone)

For Cushing’s caused by medication, your healthcare provider will likely have you taper down your dosage. This is a slow and deliberate process to keep levels from dropping too fast or too far.

Because that process can take a long time to show results, you might be given other medications to control symptoms. These may include drugs for high blood pressure, high blood sugar, or high cholesterol.

If you need treatment for anxiety or depression, you may be referred to a mental health specialist.

Recap

High cortisol levels can be caused by chronic stress, a tumor, or high levels of corticosteroid drugs. When caused by a tumor or drugs, it's called Cushing's syndrome. Treatment for stress may include psychotherapy, medication, and lifestyle changes. Treatment for Cushing's is usually surgery to remove the tumor or tapering off the dosage of corticosteroids.

Associated Conditions: Low Cortisol

Low cortisol levels also are linked to health problems. These include Addison’s disease, fibromyalgia, and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS).

Addison’s Disease

Addison’s is a rare disease. It’s also called primary adrenal insufficiency and hypocortisolism.

Addison’s is most often due to an autoimmune disease that attacks the adrenal glands. Symptoms tend to come on slowly and may come and go. They include:

  • Extreme chronic fatigue
  • Muscle weakness
  • Loss of appetite
  • Unintended weight loss
  • Abdominal pain
  • Nausea and vomiting
  • Diarrhea
  • Dizziness or fainting when you stand
  • Irritability
  • Depression
  • Joint pain
  • Cravings for salty foods
  • Low blood sugar (hypoglycemia)
  • Loss of sex drive
  • Irregular or skipped menstrual periods

Addison’s disease is treated with hormone replacement. Usually, that involves oral steroid medications such as:

These medications will be adjusted until your hormone levels are in the normal range.

Adrenal Crisis

Adrenal crisis, or Addisonian crisis, is a rapid, severe drop in cortisol levels. It can be life-threatening. Symptoms include:

  • Severe vomiting or diarrhea that can lead to dehydration
  • Pain in the abdomen, lower back, or legs
  • Fainting
  • Muscle spasms
  • Confusion and disorientation
  • Extreme thirst
  • Inability to urinate
  • Abnormal heart rhythm
  • Intermittent muscle paralysis
  • Hypotensive shock (due to low blood pressure)
  • Respiratory failure

If you experience these symptoms, seek medical help right away. Adrenal crisis leads to death in one out of 16 cases. It's treated with intravenous (IV) steroids, saline (salt water), and dextrose (a type of sugar).

Fibromyalgia and ME/CFS

The related conditions fibromyalgia and ME/CFS both feature low cortisol levels and reduced HPA-axis function. However, increasing cortisol levels with medication doesn’t improve symptoms.

That’s led experts to suspect that HPA-axis dysfunction and low cortisol are the results of the disease process in fibromyalgia and ME/CFS and not a cause of the illnesses.

Recap

Low cortisol is often due to Addison's disease, which is most often an autoimmune disorder. It's treated with hormone replacement (corticosteroid drugs). Fibromyalgia and myalgic encephalomyelitis/chronic fatigue syndrome are tied to low cortisol. But it's not believed to cause these conditions.

How Are Cortisol Levels Tested?

If you have symptoms that could point to a cortisol problem, your healthcare provider can order a blood test to look at your levels.

Typically, you’ll have blood drawn for testing twice in one day. The first test is done in the morning, when cortisol is at its peak. The second one is often done around 4 p.m., when levels are expected to be much lower.

If you’re a shift worker or have a non-standard schedule for any reason, let your healthcare provider know. The timing of the tests may need to be adjusted.

Your cortisol may also be tested in saliva or urine. For a saliva test, you’ll be given a kit to collect a sample at night, when levels should be low.

For a urine test, you’ll be asked to collect your urine for 24 hours. You’ll get a container and instructions for this.

Be certain to follow the directions carefully and to promptly return your tests to the lab for analysis.

Abnormal cortisol levels may mean Addison’s, Cushing’s, another medical condition, or a temporary change due to:

  • Higher-than-normal stress levels
  • Infection or illness
  • Pregnancy
  • Birth control pills
  • Other medications

Your healthcare provider can explain to you what your results mean and what, if any, treatments you may need. You may require more testing before they can make a diagnosis.

Summary

Cortisol is a hormone that deals with your stress response, metabolism, and many other important functions.

High cortisol is tied to chronic stress and Cushing's syndrome. Cushing's is usually treated with surgery or tapering off of the medication that caused it.

Low cortisol is tied to Addison's disease. It's usually treated with corticosteroid drugs.

Cortisol problems are diagnosed with blood, saliva, and/or urine tests.

A Word From Verywell

Symptoms of high or low cortisol should be taken seriously. At the least, you may need to make some lifestyle changes to control stress. At their worst, symptoms could point to a serious health problem or life-threatening crisis.

The good news is that cortisol-related problems are treatable and the results are usually good. Talk to your healthcare provider to start the process of figuring out what’s causing your symptoms.

Frequently Asked Questions

  • What is a good cortisol level?

    A morning cortisol level in a healthy person is between 10 and 20 micrograms per deciliter (mcg/dL).

  • What are steroids?

    Steroids are hormones that occur naturally in your body. They include sex hormones like estrogen and testosterone as well as cortisone and others. Synthetic steroids are used as medications. The most common use is as an anti-inflammatory.

  • Can Cushing's syndrome be cured?

    Yes, most of the time Cushing's can be cured. It may take a while for your symptoms to go away completely, though. You may also be left with related health problems, such as diabetes or depression.

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13 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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Additional Reading
  • Endocrine Society: Hormone Health Network. What is cortisol? Updated November 2018.

  • Society for Endocrinology: You and Your Hormones. Cortisol. Updated January 2019.