What Does Cortisol Do to Your Body and What Happens If it's Too High?

  • Medical Reviewer: Mahammad Juber, MD
Medically Reviewed on 8/25/2022

What is cortisol?

Cortisol is a hormone that plays a central role in your body's stress response. Cortisol maintains blood pressure, regulates circadian rhythm, and reduces inflammation, but if it's too high it may lead to weight gain and other symptoms.
Cortisol is a hormone that plays a central role in your body's stress response. Cortisol maintains blood pressure, regulates circadian rhythm, and reduces inflammation, but if it's too high it may lead to weight gain and other symptoms.

Cortisol is a hormone that plays a central role in your body’s stress response. This article answers questions on what cortisol does to your body and what happens when the cortisol levels in your system spike.

Cortisol is a hormone produced in your body by the adrenal glands. It regulates several mechanisms by acting as a messenger between different organs like the skin, muscles, and tissues. Cortisol, also known as the “stress hormone,” is responsible for your body’s “fight or flight” response when stressed.

Chemically, cortisol belongs to a family of compounds called glucocorticoids and plays a vital role in many physiological functions. Cortisol is widely regarded as the most important human glucocorticoid that either regulates or supports a wide variety of critical cardiovascular, metabolic, and immune functions in your body, such as:

  • Maintaining your body’s blood pressure and blood sugar levels
  • Keeping a check on your metabolism by supporting the utilization of macronutrients like fats, carbohydrates, and proteins
  • Regulating the circadian rhythm (the body’s natural cycle of sleeping and waking up)
  • Monitoring your body’s stress response
  • Reducing inflammation

The effects of cortisol on bodily functions are so vast that almost all the tissues in your body have glucocorticoid receptors. Although the adrenal glands are responsible for producing and releasing cortisol, it does this through a response mechanism that includes the hypothalamus and the pituitary glands (called the HPA axis).

Cortisol is always in circulation in your body. The cortisol levels in your saliva, urine, and blood typically see a spike at the start of the day and go down gradually throughout the day. Cortisol levels are generally at their lowest during the nighttime, around midnight.

This is usually the case when you’re following the circadian rhythm, your body’s regular sleep-wake cycle. But this can change with your activity. For example, if you’re working a night shift and sleep during the daytime, your cortisol levels may vary.

Glucocorticoids are essential for the beginning of life itself. For example, research has shown that without stress hormones, children may die before or at the time of birth.

Cortisol regulates essential physiological functions and plays a central role in successfully carrying out several other processes in your body.

Stress response

When you’re faced with a hostile or unmanageable situation, your brain triggers a series of events that involve the HPA axis to prepare an adequate response to the “stressful” situation.

The hypothalamus is a collection of cells that connect your brain and the endocrine system. The hypothalamus sends a message to your pituitary gland, which then relays the message to your adrenal glands (located above the kidneys) to ramp up the production of the stress hormone.

An increase in cortisol levels leads to higher energy availability that prepares your body for an adequate response to the situation. Cortisol does this by moving glucose and fatty acids stored in the liver. Cortisol supplies your body with the necessary energy even for routine activities and increases energy production during times of stress.

Cortisol also signals your nervous system during times of stress. Your nervous system is divided into the central (consisting of the brain and spinal cord) and the peripheral nervous system (consisting of the autonomic and somatic nervous systems).

Your autonomic nervous system is directly involved in your body’s physical response to stress. It does this via the sympathetic nervous system (PNS) and the parasympathetic nervous system (PNS).

When stressed, the SNS activates your body’s “stress response." Cortisol, along with the actions of the SNS, cause a spike in your heartbeat and increase your breathing rate. 

Your stress response also causes Your heart and your blood vessels in the larger muscle groups to dilate and increases the amount of blood in these areas, which causes a spike in your blood pressure. It also stimulates the digestive process and increases blood sugar levels during an emergency.


Inflammation is your body’s defensive mechanism to guard itself against the harmful effects of external factors. It’s an elaborate physiological process that triggers increased blood flow along with the movement of immune cells from the blood to the affected part of your body. This also lays the foundation for the healing process that overcomes inflammation by eliminating the damaged cells and tissue.

Some of the most common signs of inflammation include:

  • Swelling and pain
  • Redness of the skin
  • Warmth in the affected area
  • Inability to move or use the part of the body that’s affected

Cytokines are a type of protein released into the blood at the site of damage. These proteins activate the pain signals communicated to the brain and lead to the comprehension of pain, which stimulates the HPA axis. This, in turn, activates the production and release of cortisol, limiting cytokine production and regulating the extent of inflammation in the affected area.

The cycle of inflammation is extremely critical as otherwise, your body would be unable to attend to infections, wounds, and any other tissue or cell damage. But this response must be measured. Inadequate inflammation could lead to long-term tissue damage. On the other hand, too much inflammation could cause several conditions such as allergies, autoimmune diseases, and chronic inflammatory conditions, and in some cases could even lead to cancer.

Cortisol regulates this very critical function by lowering the inflammatory response. It does this by entering the cells and interrupting the process that makes the proteins in the cells cause inflammation.

The absence of cortisol could lead to uncontrolled inflammation, which could lead to other complications.


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Immune function

Cortisol stimulates several pathways that balance the effects of the immune system on your body’s cells and the surrounding tissue.

The body’s immune system is activated by understanding the molecules present at the site of infection (caused by pathogens) or tissue damage (caused by accidents). Once these molecules are recognized, key components of the immune system called granulocytes and monocytes carried by the blood reach the affected area.

These molecules carry out the essential immune functions such as the production of cytokines (a protein that works against infections and other diseases), antigen-speci?c antibodies, and creating an immunological memory to prevent a recurrence of the infection.

Cortisol enhances the mobility, survival, and function of the molecules that play a central role in the immune response, such as monocytes.

Blood sugar levels

Another vital function of cortisol is supplying adequate glucose levels to the brain as and when needed. Blood glucose is critical for many bodily functions and intracellular communications. Cortisol operates on the liver, muscle, pancreas, and adipose tissues to maintain adequate blood sugar levels. It does this through several processes that occur in different parts of the body.


In the liver, a process called gluconeogenesis breaks down proteins and lactate to produce glucose that will be released into the bloodstream.

Adipose tissue

Cortisol activates the process of lipolysis (breaking down triglycerides) in the adipose tissue to produce fatty acids that serve as an energy source for cells as they produce glucose.

Muscle cells

Muscles produce their own energy by breaking down glycogen into glucose through glycolysis. But in the presence of cortisol, muscle cells lower their glucose intake and break down proteins into amino acids, which are then made available for gluconeogenesis.


Cortisol acts on the pancreas to reduce insulin production and instead increases the production of a hormone called glucagon. Glucagon is essential for the process of gluconeogenesis, which leads to increased blood glucose levels.

What happens when cortisol levels change?

High cortisol levels in your blood for a long time can lead to a condition called Cushing’s syndrome and physical and mental changes. Some of these include:

  • Sudden weight gain in specific parts of your body, such as the face, abdomen, and chest, is made noticeable by the difference in the weights between these areas and the rest of the body, especially the limbs
  • Elevated blood pressure
  • Flushed face and sensitive skin
  • Anxiety and depression
  • Weak and brittle bones
  • Rapid changes in your mood
  • Irregular menstrual cycles in women

On the other hand, low cortisol levels can cause a condition called Addison’s disease (also called primary adrenal insufficiency). Although incidences of Addison’s disease are isolated, it’s an autoimmune condition that damages the adrenal glands, which are responsible for releasing cortisol.

Symptoms of Addison’s disease become evident gradually but could lead to serious consequences. Some of the symptoms of primary adrenal insufficiency include:

High cortisol levels may affect your health

Cortisol is critical for several functions in your body, such as your stress response, regulating blood sugar levels, reducing inflammation, and moderating your body’s immune response.

Your body has an inbuilt mechanism to reduce your cortisol levels once it goes up. But chronically high cortisol levels may damage this balancing process and lead to a host of serious conditions.

If you’re constantly stressed, check with your doctor to understand what can be done to keep your cortisol levels in check.

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Medically Reviewed on 8/25/2022

American Psychological Association: "Stress effects on the body."

Cleveland Clinic: "Cortisol."

Endocrine Society: "Adrenal Hormones."

Thau, L., Gandhi, J. StatPearls, "Physiology, Cortisol," StatPearls Publishing, 2022. The Hypothalamic-Pituitary-Adrenal Axis in Health and Disease: "Glucocorticoids: Inflammation and Immunity."