The Immune System And Stress

Understanding the immune system and stress

Today’s busy lifestyles can often cause stress and anxiety. However, throughout our evolution, stress has ultimately played a role in our survival. The body responds naturally to such emotions as fear, excitement and frustration. Here, the central nervous system, which controls our actions, activates the sympathetic nervous system, triggering a fight or flight response. Today, we no longer employ this instinct to escape ferocious animals or engage in hunting beasts much larger than ourselves. Instead, the cause of stress can be everyday worries, problems at work or an occasional quarrel with colleagues, relatives or friends. More serious life circumstances such as bereavement, financial pressures, a health diagnosis disappointing doctor's diagnosis, war, or the death of a loved one can lead to chronic stress.


Stress is a certain type of reaction the body produces in response to fear, tension, unpleasant emotions, monotonous activity, and bustle, manifested in the form of a malfunction of the central nervous system.1 During stressful events, the body actively produces substances that motivate a person to find a way out of the stressful state.

The physical state of stress is instigated by the sympathetic nervous system which prepares the body for danger. A major contributor to the response to stress is the rapid production of adrenaline and steroid hormones such as testosterone and cortisol, which, as hormones, can affect your mood and immune status.2

What types of stress are there?

Types of stress include 

  • Chemical stress – appears after exposure to chemical and toxic substances
  • Mental stress – can be provoked by a range of different types of emotions
  • Biologically –  this type of stress appears as a result of illness after trauma or injury
  • Eustress (Motivational stress) – is beneficial in the long term and is a useful type of shock that creates a kind of awakening in the human body
  • Distress – is a critical state related to physical strain, but is frequently used to describe anxiety. that manifests itself in overstrain, it can also be called a breakdown

Immune system

The immune system refers to a set of molecules, cells, tissues and organs that protect the body from genetically foreign cells or substances coming from the environment or formed in the body. There are two distinct immune systems that function in harmony with each other and with other systems in the body.

  • The innate immune system comprises physical barriers such as the skin, of immune cells such as white blood cells, known as monocytes and neutrophils; and small signalling molecules, known as complement, or C-reactive proteins1 (CRP) - (this test is often used in healthcare to see whether excessive inflammation or infection is present)
  • The adaptive immune system refers to antigen-sensing T-cells and antibody-producing B-cells. These immune cells are able to adapt to new toxic molecules and remember and repeat the first response should you encounter the same infection or allergen, for example

The link between the immune system and stress

Stress stimulates the immune system. Sometimes this works to our advantage, as it helps to avoid infections and speeds up the healing of wounds. But over time, stress may weaken the immune system making us more vulnerable to infectious diseases and other illnesses. A weakened immune system increases the time it takes for the body to recover from illness or injury. The connection between persistent negative experiences and the development of autoimmune diseases has been demonstrated by scientists.2 

Adrenaline reduces the body’s capacity to rest, leaving you tired. If stress is persistent this can lead to chronic fatigue which can impact the highly regulated immune response.

Cortisol is one of the major hormones released under stressful conditions. Released by the kidneys, cortisol increases blood pressure, heart rate, and sugar breakdown. Cortisol release suppresses inflammation and immune system responses.

Testosterone is a hormone released by the adrenal glands surrounding the kidneys, ovaries and testes. Testosterone can suppress the immune system, which is why people assigned male at birth (AMAB) are more susceptible to viral and bacterial infection.3,4

What else happens to the body during stress?

  • A short-term reaction to stress is the release of testosterone, but due to over-expression, its levels can decrease over time. A significant reduction in testosterone can increase irritability, affect sperm production, cause erectile dysfunction and lead to impotence. Due to a weakened immune response, the risk of infection of the genital organs in AMABs with infectious diseases also increases4 
  • Testosterone and cortisol can also affect the course of the menstruation cycle, which can become irregular and painful. In addition, constant exposure to stress-related hormones can nervous exhaustion and aggravate the physical symptoms of menopause

What are the signs of stress? 

Some of the commonly noticed signs are 

  • Irritability
  • High blood pressure 
  • Headaches 
  • Stomach and digestive problems
  • Exhaustion
  • Weakened immune system
  • Insomnia
  • Anxiety 
  • Depression
  • Panic attacks

Helpful tips to fight stress

Preventing the occurrence of stress is very important, as it is much easier to do than to deal with later consequences. To help prevent and resolve stress, the following these tips are advised: 

  • Good, healthy sleep
  • Regular exercise, preferably in the fresh air
  • Take a relaxing bath every day, which will allow you to abstract from the hustle and bustle and put your thoughts in order
  • Listen to quiet, soothing music
  • Take a sufficient amount of vitamins, especially vitamin B vitamins, as they help the body to produce melatonin, a regulator of the sleep-wake cycle
  • Control the quality of air and light in the room
  • Practice controlling your breathing as it can help to prevent and control stress
  • Eating a balanced diet, replacing processed foods with fruit and vegetables  which are easily digested by the body
  • Seek counselling from a professional if you feel overwhelmed. 


To summarise, stress is the body’s natural response to challenges in life. Stress can manifest as physical, psychological or emotional. Long-term stress can cause high blood pressure, insomnia, and irritability, and affect immune responses which can increase the risk of serious infection and disease. You can manage your stress by trying to clock in enough sleep, eating healthy, exercising in the open, listening to music and most importantly seeking professional help. 


  1. Kutlu H, Avci E, Özyurt F. White blood cells detection and classification based on regional convolutional neural networks. Medical Hypotheses [Internet]. 2020 Feb 1 [cited 2023 Oct 6];135:109472. Available from: 
  2. O’Connor DB, Thayer JF, Vedhara K. Stress and health: a review of psychobiological processes. Annu Rev Psychol [Internet]. 2021 Jan 4 [cited 2023 Oct 6];72(1):663–88. Available from: 
  3. Trigunaite A, Dimo J, Jørgensen TN. Suppressive effects of androgens on the immune system. Cellular Immunology [Internet]. 2015 Apr 1 [cited 2023 Oct 6];294(2):87–94. Available from: 
  4. Zueger R, Annen H, Ehlert U. Testosterone and cortisol responses to acute and prolonged stress during officer training school. Stress [Internet]. 2023 Jan 2 [cited 2023 Oct 6];26(1):2199886. Available from: 
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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