What Is Your Immune System?

You’ve heard of your immune system. But how much do you know about it?

There’s a good reason to find out. When you understand everything that it does for you, and how everyday things affect it, you can help it keep you well.

1. It Looks Out for You

Your immune system works to root out germs and other invaders that have no business in your body.

For example, if you inhale a cold virus through your nose, your immune system targets that virus and either stops it in its tracks or primes you to recover. It takes time to get over an infection, and sometimes you need medicine to help, but the immune system is the cornerstone of prevention and recovery.

2. It Likes It When You Relax

Do your best to tame your stress. When you’re wound up, your immune system doesn’t work as well as it does when you’re confident and mellow about your challenges. That may make you more likely to get sick.

3. It’s Got Agents Standing By.

Other than your nervous system, your immune system is the most complex system in your body. It’s made up of tissues, cells, and organs, including:

  • Your tonsils
  • Your digestive system
  • Your bone marrow
  • Your skin
  • Your lymph nodes
  • Your spleen
  • Thin skin on the inside of your nose, throat, and genitals

All of these help create or store cells that work around the clock to keep your whole body healthy.

4. It Learns From Your Past

You’re born with a certain level of protection, or “immunity.” But it can get better.

Think of a baby or young child who comes down with colds, earaches, or other everyday illnesses often and babies who are breast feed continue to get antibodies from their mother while they are making their own.. Their immune system is creating a "bank" of antibodies as they are exposed to illnesses for the first time, enabling them to fight off future invaders. 

Vaccines work in much the same way. They turn on your immune system by introducing your body to a tiny amount of a virus (usually a killed or weakened one). Your body makes antibodies in response that protects against threats like measles, whooping cough, flu, or meningitis.Then, when you come in contact with that virus in your everyday life, your immune system is already primed to kick in so that you don’t get sick.

5. It Can Change Over Time

Your immune system can become less effective as you get older. That can make you more likely to get sick or get infections. You are also more susceptable to infections as you age or if you have a weakened immune system.

6. Medical Conditions that Weaken your immune system

Conditions which can weaken you immune system include:

  • autoimmune diseases
  • cancer
  • steroids
  • chemotherapy

7. You Can Help It Out

The classic things that keep your heart, brain, bones, and the rest of you well are also good for your immune system:

  • Eat nutritious foods.
  • Stay active.
  • Work to keep your weight healthy.
  • Don’t smoke.
  • If you drink alcohol, keep it moderate (no more than one drink a day if you’re a woman, and two drinks daily if you’re a man).
WebMD Medical Reference Reviewed by Sabrina Felson, MD on October 19, 2019



American College of Rheumatology: "The immune system and its link to rheumatic disease."

CDC: "Immunity types," "Vaccines and immunizations" and "Alcohol and public health." 

Harvard Medical School: "How to boost your immune system."

National Institute of Allergy and Infectious Diseases: "Immune System."

University of Rochester Medical Center: "All about the immune system."

U.S. National Library of Medicine: "How does the immune system work?" and "What are the organs of the immune system?"

Vaccines.gov: "Immunity: Natural and acquired."  

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