Cortisol and Immunity

Find out how cortisol affects your Immunity so that you can manage your lifestyle and reduce your risk of illness

What is the immune system?

The immune system is a network of tissues, cells, and organs that fights off germs like bacteria, viruses, fungi and parasites. Helping the body to fight them off with them if they manage to get into the body.

There are two main parts to the immune system:

The Innate immune system that you are born with and the adaptive immune system which we develop as the body is exposed to microbes and the environment.

Maintaining a healthy immune system is one of the key ways you can protect yourself from illness.

Main roles of the immune system

To work effectively the immune system needs distinguish between normal, healthy cells and unhealthy cells. One of the ways it does this is by recognizing a variety of "danger" cues from cells within the body. These are called danger-associated molecular patterns (DAMPs).

There are trillions of cells within the immune system and each cell has a different function. These cells need to communicate with each other effectively in order to mount a good immune response and fight off ‘invaders’.

The main roles of the immune system include:

  • to fight ‘pathogens’ like bacteria, viruses, parasites or fungi, and to remove them from your body
  • to recognize and remove harmful substances from the environment within your body
  • to fight disease-causing changes in your body, such as cancer cells

Did you know?

The immune system has trillions of cells such as Cytokines, Natural Killer cells and Helper ‘T’ cells. Every kind of cell within the immune system has receptors for cortisol and a different role within the body.

Managing your cortisol levels over time will help you prevent infectious illnesses and reduce your risk of future poor health.

How does cortisol affect the immune system

Cortisol is a glucocorticoid hormone that regulates the immune system and playing crucial roles in helping to keep inflammation within the body down.

In order for the immune system to work properly it relies on a complex balance of signals between cells and other systems including your HPA axis in the body.

One of the main jobs of cortisol is to switch the immune system ‘on and off’ by sending signals to your immune cells, which affects when and how an immune response is mounted.

Cortisol levels that are too low or too high over time can dysregulate the immune system leading to increased risk of illness and infection.

Cortisol levels that are too low or high can:

  • Increases your risk of infections and viruses
  • Your wounds are slower to heal
  • Reduces your body’s ability to defend against bacteria, viruses, parasites and cancer cells

Signs and symptoms

What are the symptoms of high and low cortisol?

  • Feeling unwell
  • Regular infections
  • Severe Fatigue
  • Low mood
  • Diarrhea, nausea and vomiting
  • Headaches
  • Cognitive difficulties
  • Depression
  • Anxiety
  • Bone loss and weakness
  • High blood pressure
  • Decreased Libido
  • Difficulty getting pregnant
  • Irregular periods
  • Erectile dysfunction
  • Low blood sugar
  • Weight gain or weight loss

Did you know?

People with higher cortisol levels are more prone to the Covid-19 virus and are more likely to have worse symptoms.

Research has shown that the risk of mortality is greater in those with highest levels of the hormone.

How to reduce your risk of infectious illness

A healthy immune system is crucial for maintaining good health and reducing your risk of infectious illness.

Your lifestyle over time can affect how well your immune system works and it’s ability to protect you from germs, viruses and chronic illness.

The best way to boost your immune system is to choose to adopt a healthy lifestyle.

How to boost your immunity

1. Check your cortisol levels

Your cortisol levels over time are important for maintaining immune function. By regularly testing your cortisol levels you can see how your lifestyle may be affecting your immunity and make changes to improve your overall health.

2. Stop smoking

Smoking reduces immunity and has widespread effects on other systems within the body leading to an increased risk of infectious illness and chronic disease. Smoking dyregulates cortisol levels leading to serious consequences for your overall health.

3. Cut out alcohol

Research has shown that high doses of alcohol (around 14 drinks per week or more than five to six drinks at a time) can suppress the immune system, and that alcohol abuse is associated with increased risk of infectious diseases.

4. Eat well

Studies suggest that a person's diet affects their immune system, like all other aspects of health. For example, nutrition can affect cortisol levels, the microbiome, gut barrier function, inflammatory processes, and white blood cell function, all of which impact immune function

A balanced diet consisting of whole fruits, vegetables, lean proteins, whole grains and plenty of water is important for overall health and maintaining a healthy immune system.

Nutrients that are critical for the growth and function of immune cells include:

  • Vitamin C
  • Vitamin D
  • Zinc
  • Selenium
  • Iron
  • Protein

If a balanced diet is not readily accessible then consider taking a multivitamin.

5. Manage stress

There are several ways you can help manage stress. Remember that what works for one person may not for another so find what works for you.

  1. Recognise when stress is a problem
  2. Think about where you can make changes
  3. Build supportive relationships
  4. Eat healthily
  5. Be aware of unhealthy behaviour such as smoking and drinking too much
  6. Get some exercise
  7. Take time out
  8. Try mindfulness
  9. Get some restful sleep
  10. Regularly check you cortisol levels

6. Exercise in Moderation

Exercising in moderation will help improve and maintain your immune system. This will help to reduce your risk of immune related illness and future illness.

It’s important to know that the intensity of exercise matters. Exercise can have both a positive and negative effect on cortisol levels and the functioning of the immune system.

Adults should do some type of physical activity every day. Exercise just once or twice a week can improve your immunity and reduce your risk of poor health.

Adults should aim to:

  • do strengthening activities that work all the major muscle groups (legs, hips, back, abdomen, chest, shoulders and arms) on at least 2 days a week
  • do at least 150 minutes of moderate intensity activity a week or 75 minutes of vigorous intensity activity a week
  • spread exercise evenly over 4 to 5 days a week, or every day

    7. Get a good night sleep

    Getting the right amount of sleep will help to regulate your cortisol levels and maintain your immune system. Try to keep regular sleeping hours and get rid of distractions, such as your mobile phone, that may cause you to have a disrupted night sleep.


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