Cold vs. Flu: Signs, Symptoms, & Stages

’Tis the season…for the sniffles. Alongside holiday cheer, cold and flu viruses are all around us. If you do catch one of them, it’s helpful to understand your symptoms and know when you’re most contagious—so you can avoid sharing the bugs with those around you.

Is it just a cold, or is it the flu?
Sometimes it can be hard to tell. While both the common cold and the flu are respiratory illnesses, they are caused by different viruses.1 But because symptoms are similar, it may take a little detective work to determine which of these is ailing you.

Approximately one billion Americans catch colds each year.2 Symptoms show up gradually and often begin with a sore throat that is later accompanied by congestion (stuffy or runny nose), headaches, and general malaise. With rest and TLC, a cold may ease up within a week.3

While the same feelings of stuffiness may occur, the flu is characterized by the sudden onset of fever, aches and chills, dry cough, and extreme fatigue.4 Unlike colds, the flu can give way to secondary bacterial infections, pneumonia, and other risks,1 so it’s important to take time off and get the rest your body needs to recover. Both children and elderly people are at an increased risk of catching the flu due to lower immunity.1

Stages of illness

Your body goes through several stages when you become ill with a respiratory virus. First, it undergoes a period of incubation (1-2 days) when it is first exposed to the organism. As the virus takes over, onset occurs and symptoms show up—letting you know that you’re unwell. While the flu may hit suddenly, you may detect less obvious signs that you’re coming down with a cold, such as a funny feeling in your throat or feeling tired. As the illness progresses, symptoms may worsen before your body recovers and begins to heal itself.

When am I contagious?

You are most contagious during the incubation period—before symptoms even start. For both cold and flu, this can persist for several days after you’ve begun to feel sick.4 That’s why allowing yourself adequate downtime early on is so necessary.

Cold and flu germs can spread very easily. When you sneeze or cough, germs are expelled through the air and may land on other surfaces or objects, where they can survive for several hours. Touching objects or surfaces with germ-laden fingers carries a big risk for those around you, as they may pick up those germs and become infected.4 To spare friends, family, or coworkers of a similar fate, it’s best to stay home and give your body plenty of recovery time.

Staying well

No one likes getting sick. Whether there’s a cold or flu floating around your household or office, there are ways to be proactive about your health. If you catch something, do yourself and others a favor by staying home and getting some much-needed rest. If your illness persists or shows excessive symptoms, contact your healthcare practitioner.

This information is for educational purposes only. This content is not intended as a substitute for professional medical advice, diagnosis, or treatment. Individuals should always consult with their healthcare professional for advice on medical issues.


  1. Centers for Disease Control and Prevention. Cold Versus Flu. CDC. Accessed November 20, 2018.
  2. U.S. Department of Health & Human Services. Understanding a Common Cold Virus. National Institutes of Health. Accessed November 20, 2018.
  3. Allan GM et al. Prevention and treatment of the common cold: making sense of the evidence. CMAJ. 2014;186(3):190–199.
  4. U.S. Department of Health & Human Services. All About the Flu and How to Prevent It. National Institutes of Health. Accessed November 22, 2018.      

Submitted by the Metagenics Marketing Team

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