5 Issues That Can Harm Your Immune System

Do you seem to always be fighting a cold or other ailment? Your immune system may not be up to par. This collection of cells, tissues, and proteins teams up against a daily onslaught of bacteria and viruses to stave off infection and keep you healthy.

Serious illness or disease may reduce your immune function and leave you vulnerable to further infection, but some of life’s most common situations and conditions also may weaken your immunity. Here are some of the typical culprits:

1. Stress

Stress causes your adrenal gland to produce excess cortisol, also known as the “fight or flight” hormone. Too much cortisol and you might find your immune system out of whack. In fact, studies have shown that people under serious stress—such as those caring for ill relatives or people going through a divorce or job loss—produce less of an immune response when given the flu vaccine (which is designed to provoke a mild immune reaction) than those who are not under much stress.

"But it doesn’t always have to be bad stress [that impairs the immune system]," notes Kathryn Boling, MD, a primary care physician at Lutherville Personal Physicians in Lutherville, MD., a division of Baltimore’s Mercy Medical Center. Even happy events such as planning a wedding, preparing for and executing a move, or transitioning to a new job all can all stress the immune system. "Any stress that goes on for a long time (for weeks or months)…will cause the same physiological [functional] changes in the body," she adds.

The fix: Meditation. A study out of Stanford University in CA. demonstrated that stressed-out subjects who meditated managed to mount a better immune response to the flu vaccine. If formal meditation instruction isn’t for you, find a book on the subject, or download a free meditation app onto your smartphone.

2. Obesity, Poor Diet, and/or Lack of Exercise

This combination can inhibit your immune functioning in a variety of ways. Being overweight can prevent white blood cells (your body’s disease fighters) from increasing and checking inflammation, while excessive sugar consumption can hinder your ability to fight viruses and bacterial infections. And a lack of physical of activity actually ups your odds of getting sick, since exercise helps white blood cells circulate faster, slows the release of cortisol, and may flush bacteria out of the lungs. Just don’t overdo the exercise, as workouts that are too intense can also lower your immunity.

The fix: Eat a variety of fruits and vegetables and as much unprocessed food as possible, and incorporate physical activity into each day.

3. Depression

Depression not only feels bad mentally, it can also take a physical toll. "People with depression may have increased levels of cortisol, adrenaline, and other stress hormones, as well as increased inflammation throughout the body," Boling says.

The fix: Treat depression with talk therapy, medication, or a combination of both. Medication may be a particularly potent approach: Antidepressant medications such as selective serotonin reuptake inhibitors (SSRIs; Prozac, or fluoxetine is one) can actually boost the activity levels of natural killer cells, which are potent tools your body produces to fight off cancer and viral infections.

4. Social Isolation

Lonely folks don’t do as well, health-wise, as more connected people. Numerous studies have found that loners become ill more often, end up sicker, and heal more slowly than social butterflies. As Boling puts it, "Loneliness functions as a chronic stressor that leads to a poor immune response."

The fix: Cultivate and nurture relationships. Having a circle of supportive friends, a caring partner, or good relationships with relatives can offer a big health boost. If you’re not sure how to go about this, start by signing up for a class or even joining an online community focusing on a topic you’re interested in.

5. Certain Medications

Although they may be necessary, some medications have the undesirable effect of lowering your immune response. Besides immunosuppressants (drugs that inhibit the immune system, often prescribed to organ transplant recipients, for instance), corticosteroids—commonly used by people with asthma or rheumatoid arthritis—can produce this result.

The fix: Get vaccinated before taking these medicines, if you can, and take care to avoid putting yourself into situations in which you are exposed to serious illnesses and infections.

Other things that can damage your immune system include:

  • Regular smoking.
  • Heavy drinking.
  • Too little sleep.

Do your best to avoid these drains on your immune system.

Kathryn Boling, MD, reviewed this article.


Boling, Kathryn, MD. Email message to author. April 8, 2015.

"Exercise and Immunity." MedlinePlus. Updated May 11, 2014.

"Immune System." National Institute of Allergy and Infectious Diseases. Accessed April 29, 2015.

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Davidson R.J., J. Kabat-Zinn, J. Schumacher, M. Rosenkranz, D. Muller, S.F. Santorelli, F. Urbanowski, A. Harrington, K. Bonus, J.F. Sheridan. "Alterations in Brain and Immune Function Produced by Mindfulness Meditation." Psychosomatic Medicine 65, 4 (2003): 564-70. Accessed May 4, 2015.