Stress Effects Immune System

The fight-or-flight stress response is nature’s way of helping you survive a threat where you need to either run or fight. Ongoing stress, however, puts a strain on health in a number of areas, including the immune system.

Effects of Stress on Cortisol

When you’re experiencing stress, your cortisol levels rise. This hormone–produced in the adrenal glands–is actually helpful to the body in small quantities. It helps speed tissue repair and has anti-inflammatory properties.

During long periods of stress, higher-than-healthy levels of cortisol inhibit the production of prostaglandins, anti-inflammatory substances that dilate blood vessels and support various functions of the immune system.

Despite the fact that cortisol has anti-inflammatory properties, low levels of prostaglandin result in immune suppression and inflammation. When cortisol levels are high for prolonged periods of time, immune system cells actually shut off and stop working. Sometimes these cells can even unleash their destructive abilities on the body’s tissues and result in allergies and autoimmune diseases. Natural killer cells, a major component of the immune system, are the immune cells most sensitive to cortisol.

If exposed to prolonged stress, the adrenal glands may become fatigued, causing a drop in cortisol and other hormones, which can then cause an excess of immune cells in your bloodstream, possibly resulting in illness and disease.

Stress and Disease

When the immune system doesn’t function properly, the body is vulnerable to a number of health problems, including:

  • Allergies
  • Asthma
  • Autoimmune diseases
  • Digestive, respiratory, skin and other infections
  • Hives and rashes.

A poorly functioning immune system can also contribute to the onset and progression of coronary artery disease and heart attacks. Some scientists believe that the link between stress and disease may even branch out to cancer.

Research: Effects of Stress and Disease

A 2003 Ohio State University study revealed that people subjected to the constant stress of caring for chronically ill loved ones had impaired immune function.

Participants included 117 caregivers of people with Alzheimer’s disease and other forms of dementia, and a control group of 106 adults who didn’t have to provide this type of care.

Those in the caregiver group were found to have levels of Interleukin-6 (IL-6) about four times larger than the control group. (Increased levels of IL-6 are associated with higher risk for diseases including arthritis, certain cancers, osteoporosis and Type 2 diabetes.)

These increased levels of IL-6 remained as long as three years after subjects no longer had to care for a loved one, suggesting that intense, ongoing stress may permanently damage the immune system.

Previous research by the same group of scientists at Ohio State University revealed other startling connections between stress, disease and immunity. These studies concluded that stress impacts the effectiveness of certain vaccines, as well as recovery times for wounds.


Benjamin Associates. (2007). Stress and the immune system. Retrieved September 25, 2010, from

Ohio State University. (2003). Mechanism found that weakens caregivers’ immune status. Retrieved September 30, 2010, from­ /releases/2003/07/030701223023.htm

Stress Affect. (2010). How does stress affect the immune system? Retrieved September 25, 2010, from