How Does Stress Affect Your Immune System?

Dreading cold and flu season because you always get sick? Can’t seem to recover from a cold before coming down with yet, another? Feeling exhausted and burnt out? It may be, because your body is more stressed than you realize.

Unraveling the connection:
The endocrine system, the system that regulates metabolism, growth, and development, amongst other things, is made up of intricately connected glands. The most significant of these glands are the hypothalamus, the pituitary, and adrenal glands; the three together make up what is known as the HPA axis (2).

During times of stress, your HPA axis increases production of the hormone cortisol to help you cope with stress. Cortisol exerts its effects in your tissues, it increases blood sugar, inhibits digestion, and puts a halt on immune activity, and when a sufficient response has occurred, its production is halted (3).

Sounds pretty straightforward right? … But what happens if the demand for cortisol continues without ever reaching a sufficient adaptive response?

How does ‘stress’ get inside the body to affect the immune system?

Prolonged stress, be it emotional, physical, mental, or environmental creates a state of continuously elevated cortisol, which impacts your ability to mount an appropriate immune response.

Firstly, sympathetic (flight or flight signals) descend from our brain to our primary and secondary lymphoid tissues. The signals release a variety of substances that bind to receptors on our white blood cells to influence immune response.

It’s been demonstrated in several studies that chronic stress elicits simultaneous enhancement and suppression of the immune response by altering patterns of cytokine secretion (1). Th1 cytokines, which activate cellular immunity to fight infection and neoplasm are suppressed, leading to increase in infection and cancer, while Th2 cytokine activity increases, leading to allergy and autoimmune disease. This shift can occur via the effects of our stress hormone, cortisol (1).

Secondly, it’s important to understand that our efforts to manage the demands of stressors often leads us to engage in unhealthy behaviours such as changes in sleeping patterns, unhealthy food choices, reduction in exercise, or alcohol or drug use.

What can you do to?

Book an appointment with your naturopathic doctor. Lowered immunity is not the only symptom of elevated cortisol. Fatigue, food cravings, weight gain, depression, anxiety, brain fog, insomnia, digestive disturbance and more can all be associated with cortisol dysregualation.

If you suspect stress may be contributing to your health concerns, consider having your cortisol levels evaluated. Salivary cortisol testing is an accurate method for determining your cortisol levels and its pattern throughout your day. Understanding where your cortisol levels are at will help to establish what course of action to take.

Diet is key. There are many dietary and supplemental supports that work to normalize cortisol levels, and physical therapies such as massage, acupuncture, counseling, and meditative techniques can help to reduce your body’s experience of stress.

If you are sick – stay home and rest!

It doesn’t pay to push through. One research study proposed immunological activation results in a behavior known as sickness behavior, behavioural changes such as reduced activity, social interaction and sexual activity, as well as increased responsiveness to pain, anorexia and depressed mood. This ‘syndrome’ is likely adaptive in that it results in energy conservation at a time when energy is best directed toward fighting infection (1).

By Dr. Alaina

1. Segerstrom SC, Miller GE. Psychological Stress and the Human Immune System: A Meta-Analytic Study of 30 Years of Inquiry. Psychological bulletin. 2004;130(4):601-630. doi:10.1037/0033-2909.130.4.601.
2. Mitrovic, I. (2013). Introduction to the Hypothalamo-Pituitary-Adrenal (HPA) Axis. [lecture]. Retrieved October 24, 2016 from
3. Lam, M. (2016). OAT Axis Imbalance. In Dr. Lam Adrenal Fatigue Center. Retrieved October 24, 2016 from