Cold, Flu, & Cough Health Center

Glossary of Flu Terms

Medical terms related to the flu can be confusing. Here are brief definitions for common terms you may hear from your doctor or friends.

Antibacterial. Capable of killing bacteria or slowing their growth.

Antibiotics. Medicines that treat infections by killing bacteria; they have no effect on viruses, like the flu.

Antibiotic resistance. A condition in which bacteria adapt to an antibiotic medicine and become immune to it. This is a big concern due to prescribing antibiotics when they are not needed or effective.

Antiviral agent. Drugs that treat viral infections. Flu antivirals like Tamiflu or Relenza can be used to treat the flu (if given within 48 hours of becoming sick) or to prevent it in people at high risk.

Bacteria. Microscopic one-celled organisms, some of which can cause illness.

Bronchitis. Inflammation of the airways leading to the lungs; it can be caused by viruses or bacteria.

Common cold. A viral infection of the upper respiratory tract; colds are unrelated to influenza.

Germs. Any microbes, including viruses or bacteria.

Immune system. The group of organs and specialized cells in the body that protect against disease.

Immunity. Protection from disease.

Immunization. A way of making a person immune to a disease; specifically by vaccination.

Influenza. Also called the flu, a common but sometimes serious viral infection of the respiratory tract, causing congestion, fever, body aches, and other symptoms.

Microbe. A microscopic organism.

Nasal vaccine. A vaccination, like FluMist, that is inhaled through the nose, rather than injected.

Pneumonia. Inflammation of the lungs, causing fever, chills, cough, chest pain, and difficulty breathing, that is often caused by a viral or bacterial infection.

Reye's syndrome. A life-threatening brain disease that can follow infection with a virus, like the flu, and is most common in children; it’s associated with taking drugs containing aspirin.

Sinusitis. Swelling of the sinuses, especially the ones around the nasal passages; it might be caused by infection with a virus or bacteria.

"Stomach flu." The informal name for gastrointestinal illnesses caused by any number of different microbes; it has no relation to actual influenza.

Vaccine. A substance, often given by injection, that protects against a disease; vaccines contain a dead or weakened version of a microbe, which spurs the immune system to recognize and destroy the living microbe during future infection.

Virus. A microscopic organism that invades living cells to reproduce; many, like influenza, cause illness. A virus is not affected by antibiotics.