Skip to main navigation Skip to main content Skip to footer For Medicare For Providers For Brokers For Employers Español For Individuals & Families: For Individuals & Families Medical Dental Other Supplemental Explore coverage through work How to Buy Health Insurance Types of Dental Insurance Open Enrollment vs. Special Enrollment See all topics Shop for Medicare plans Member Guide Find a Doctor Log in to myCigna
Home Knowledge Center Wellness Library Immune System

Immune System

Learn about the immune system

The immune system is the body's natural defense system that helps fight infections by attacking the germs that cause diseases. But just like with any other part of your body, there can be problems with your immune system. Human immunodeficiency virus (HIV) is an example of a virus that damages the immune system so that the body is unable to fight infections. And sometimes the immune system mistakenly attacks the body's own cells. This is known as an autoimmune disease. This kind of disease, such as rheumatoid arthritis or lupus, can be very hard to deal with. Our topics can help you cope with immune system problems. We can also show you how to strengthen your immune system against common diseases.

Get the information you need in our immune system topics, such as:

  • Immunizations.
  • Lupus (Systemic Lupus Erythematosus).
  • Rheumatoid Arthritis.
  • Human Immunodeficiency Virus (HIV) Infection.
  • Sjögren's Syndrome.
  • Multiple Sclerosis: Should I Start Taking Medicines for MS?
Health Topics
  • Acquired Von Willebrand Disease
  • Addison's Disease
  • Allergic Reaction to Tattoo Dye
  • Allergies to Insect Stings
  • Allergies: Rush Immunotherapy
  • Allergy Shots for Allergic Rhinitis
  • Allergy Shots for Asthma
  • Allergy to Natural Rubber (Latex)
  • Antibiotics
  • Antihistamines
  • Antiretroviral Medicines for HIV
  • Arthroplasty for Rheumatoid Arthritis
  • Arthroscopy for Rheumatoid Arthritis
  • Atopic Dermatitis (Eczema)
  • CD4+ Cells
  • Celiac Disease
  • Chickenpox (Varicella)
  • Chikungunya Fever
  • Comparing Rheumatoid Arthritis and Osteoarthritis
  • Complications of Lupus
  • COVID-19: Prevention for People With Weakened Immune Systems
  • Crohn's Disease
  • Diabetes and Infections
  • Disease-Modifying Antirheumatic Drugs (DMARDs)
  • Ebola or Marburg Virus Infection
  • Environmental Illness
  • Fever or Chills, Age 11 and Younger
  • Fever or Chills, Age 12 and Older
  • Flu Vaccine Myths
  • Flu: Signs of Bacterial Infection
  • Guillain-Barré Syndrome
  • Helping Children During Immunizations
  • Hidden Gluten
  • HIV (Human Immunodeficiency Virus) Infection
  • HIV and Exercise
  • HIV and Fatigue
  • HIV and Pregnancy
  • HIV and Weight Loss
  • HIV Home Care
  • HIV Infection in Health Professionals
  • HIV Screening
  • HIV Treatment in Children
  • HIV Viral Load
  • HIV: Antiretroviral Therapy (ART)
  • HIV: Giving Support
  • HIV: Nonprogressors and HIV-Resistant People
  • HIV: Preventing Infections
  • HIV: Preventing Other Infections When You Have HIV
  • HIV: Stages of Infection
  • HIV: Tips for Caregivers to Avoid Infection
  • HIV: Why Healthy Eating Matters
  • Hyperthyroidism
  • Immunizations
  • Immunizations and Pregnancy
  • Immunizations for Premature Infants
  • Immunizations That May Cause Fever
  • Immunizations: Questions Parents Ask
  • Immunoglobulin
  • Immunotherapy for Allergies to Insect Stings
  • Importance of Immunizations
  • Indirect Coombs Test
  • Influenza (Flu) Vaccine (Inactivated or Recombinant): What You Need to Know
  • Influenza (Flu) Vaccine (Live, Intranasal): What You Need to Know
  • Interactive Tools
  • Intrauterine Fetal Blood Transfusion
  • Juvenile Idiopathic Arthritis
  • Juvenile Idiopathic Arthritis: Deciding About Total Joint Replacement
  • Juvenile Idiopathic Arthritis: Inflammatory Eye Disease
  • Juvenile Idiopathic Arthritis: Pain Management
  • Juvenile Idiopathic Arthritis: Range-of-Motion Exercises
  • Juvenile Idiopathic Arthritis: Stretching and Strengthening Exercises
  • Living With More Than One Health Problem
  • Lupus (Systemic Lupus Erythematosus)
  • Lupus and Antiphospholipid Antibody Syndrome
  • Lupus and Pregnancy
  • Lupus: Criteria for Diagnosis
  • Lupus: Healthy Eating
  • Methicillin-Resistant Staphylococcus Aureus (MRSA)
  • Mononucleosis (Mono)
  • Mononucleosis Complications
  • Mouth Sores
  • Multisystem Inflammatory Syndrome in Children (MIS-C)
  • Myalgic Encephalomyelitis/Chronic Fatigue Syndrome
  • Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Getting Support
  • Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Managing Your Energy
  • Necrotizing Fasciitis (Flesh-Eating Bacteria)
  • Neutropenia: Preventing Infections
  • Nonallergic Rhinitis
  • Opportunistic Infections in HIV
  • Organ Transplant
  • Organ Transplants: Antirejection Medicines
  • Peanut Allergy
  • Phototherapy for Atopic Dermatitis
  • Phototherapy for Psoriasis
  • Pneumocystis Pneumonia and AIDS
  • Polymyalgia Rheumatica
  • Preventing Tetanus Infections
  • Primary Biliary Cholangitis (PBC)
  • Pseudomonas Infection
  • Psoriasis
  • Psoriatic Arthritis
  • Recombinant Zoster (Shingles) Vaccine: What You Need to Know
  • Resistance to HIV Medicines
  • Rh Sensitization During Pregnancy
  • Rheumatoid Arthritis
  • Rheumatoid Arthritis: Classification Criteria
  • Rheumatoid Arthritis: Finger and Hand Surgeries
  • Rheumatoid Arthritis: Neck Symptoms
  • Rheumatoid Arthritis: Systemic Symptoms
  • Rubella (German Measles)
  • Sarcoidosis
  • Scleroderma
  • Self-Care for AIDS Caregivers
  • Sepsis (Septic Shock)
  • Shingles
  • Sjögren's Syndrome
  • Staph Infection
  • Swollen Glands, Hernias, and Other Lumps Under the Skin
  • Swollen Lymph Nodes
  • Synovectomy for Rheumatoid Arthritis
  • Temporal Artery Biopsy
  • Tetanus
  • Thrush
  • Travel Health
  • Types of Hair Loss
  • Ulcerative Colitis
  • Vaccine Information Statements
  • Vaccines to Prevent the Flu
  • Valley Fever
  • Vancomycin-Resistant Enterococci (VRE)
  • Ways HIV Cannot Be Spread
  • Zika Virus
Medical Tests
  • Antibiotic Sensitivity Test
  • Antibody Tests for Lupus
  • Antinuclear Antibodies (ANA) Test
  • Autoimmune Disease Tests
  • Cancer Antigen 125 (CA-125) Test
  • CD4+ Count Test
  • Celiac Disease Antibodies Test
  • Cold Agglutinins Test
  • Complement Test
  • Coombs Test
  • C-Reactive Protein (CRP) Test
  • Fetal Blood Sampling (FBS) During Pregnancy
  • Gallium Scan
  • HIV Viral Load Test
  • Human Immunodeficiency Virus (HIV) Test
  • Immunoglobulins
  • Mononucleosis Tests
  • Rheumatoid Factor (RF) Test
  • Rubella Test
  • Sedimentation Rate (Sed Rate)
  • Tissue Type Test
  • Toxoplasmosis Test
  • Viral Tests
Make a Wise Decision
  • Flu Vaccines: Should I Get a Flu Vaccine?
  • HIV Testing: Should I Get Tested for Human Immunodeficiency Virus?
  • HPV: Should I Get the Vaccine?
  • Shingles: Should I Get a Vaccine to Prevent Shingles?
Take Action
  • Allergies: Avoiding Indoor Triggers
  • Allergies: Avoiding Outdoor Triggers
  • Arthritis: Managing Rheumatoid Arthritis
  • Celiac Disease: Eating a Gluten-Free Diet
  • HIV: Taking Antiretroviral Drugs
  • Sjögren's: Caring for Yourself at Home

This information does not replace the advice of a doctor. Healthwise, Incorporated, disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use. Learn how we develop our content.

© 1995-2022 Healthwise, Incorporated. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated.

<cipublic-spinner variant="large"><span>Loading…</span></cipublic-spinner>

Page Footer

I want to...

Get an ID card File a claim View my claims and EOBs Check coverage under my plan See prescription drug list Find an in-network doctor, dentist, or facility Find a form Find 1095-B tax form information View the Cigna Glossary Contact Cigna

Audiences

Individuals and Families Medicare Employers Brokers Providers

Secure Member Sites

myCigna member portal Health Care Provider portal Cigna for Employers Client Resource Portal Cigna for Brokers

Cigna Company Information

About Cigna Company Profile Careers Newsroom Investors Suppliers Third Party Administrators International Evernorth

 Cigna. All rights reserved.

Privacy Legal Product Disclosures Cigna Company Names Customer Rights Accessibility Non-Discrimination Notice [PDF] Language Assistance [PDF] Report Fraud Sitemap

Disclaimer

Individual and family medical and dental insurance plans are insured by Cigna Health and Life Insurance Company (CHLIC), Cigna HealthCare of Arizona, Inc., Cigna HealthCare of Illinois, Inc., and Cigna HealthCare of North Carolina, Inc. Group health insurance and health benefit plans are insured or administered by CHLIC, Connecticut General Life Insurance Company (CGLIC), or their affiliates (see a listing of the legal entities  that insure or administer group HMO, dental HMO, and other products or services in your state). Accidental Injury, Critical Illness, and Hospital Care plans or insurance policies are distributed exclusively by or through operating subsidiaries of Cigna Corporation, are administered by Cigna Health and Life Insurance Company, and are insured by either (i) Cigna Health and Life Insurance Company (Bloomfield, CT); (ii) Life Insurance Company of North America (“LINA”) (Philadelphia, PA); or (iii) New York Life Group Insurance Company of NY (“NYLGICNY”) (New York, NY), formerly known as Cigna Life Insurance Company of New York. The Cigna name, logo, and other Cigna marks are owned by Cigna Intellectual Property, Inc. LINA and NYLGICNY are not affiliates of Cigna.

All insurance policies and group benefit plans contain exclusions and limitations. For availability, costs and complete details of coverage, contact a licensed agent or Cigna sales representative. This website is not intended for residents of New Mexico.

Selecting these links will take you away from Cigna.com to another website, which may be a non-Cigna website. Cigna may not control the content or links of non-Cigna websites. Details