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Common cold versus the flu — which is which?

By Erin Louks-Smith, M.D.

We’re in the midst of the cold and flu season. It would be bad enough to have a cold season, or a flu season, but here in the Northland, we get to experience both. No one wants to be sick — with either a cold or the flu, but when the symptoms hit, how do you know which you have?

While there are important differences between a cold and the flu, let’s start with a few similarities.

Both colds and the flu are caused by viruses. Both cause respiratory illness that spread through tiny droplets released in the air when an infected person sneezes, coughs or talks. The germs enter the body through the mucous membranes in the nose, mouth or eyes when they are inhaled or when a person makes contact with the droplets on a contaminated surface or object and then touches his or her eyes, nose or mouth.

There is some overlap of symptoms between a cold and the flu, but there are differences in severity of those symptoms and the way they manifest. Symptoms of the flu come on hard and fast, while those with a cold develop gradually over the course of a few days.

Symptoms of the common cold are centered in the head and nose. They include sneezing, stuffy nose, mildly sore throat and a hacking cough.

The flu affects the entire body — with aches, chills, fatigue, headache and a fever of 101 degrees or higher (all less common in a cold). Coughing is also common, but more severe than with a cold. The symptoms most common with a cold — sneezing, stuffiness and sore throat — can accompany the flu, but not always. 

It is impossible to tell whether you have a cold or the flu by symptoms alone. Diagnosis of the flu is done through lab tests by a health care professional, which requires only a simple swab of your nose in most cases.

A cold is typically less severe than the flu. A person with a cold may feel sick, but can still perform regular daily activities. A person with the flu is more run down and likely to be sick in bed.

A cold runs its course in a matter of days. A day or two of a mildly sore throat is usually followed by congestion, a runny nose and finally, a hacking cough by day four or five. Usually a cold runs its complete course in a week. If you experience symptoms for a longer period, you may have allergies or a sinus infection.

Flu symptoms come on all at once and gradually improve over the next two to five days, but it’s not uncommon to feel symptoms for a week or more. A complication of the flu is pneumonia. Shortness of breath, or having a fever that goes away and then returns after a few days are signs of possible pneumonia.

One major difference between a cold and the flu is that the flu is preventable. When supplies are sufficient, the Center for Disease Control recommends the flu vaccine for all persons, regardless of risk. Other simple ways to avoid the germs that cause colds and the flu is by washing your hands often and thoroughly and avoiding touching your face with your hands.

While both colds and the flu are viral infections, the cold is caused by hundreds of different viruses; the flu is caused by two or three different viruses each year. The flu vaccine is created based on research regarding what these viruses will be and therefore is different each year. While the scientific predictions about which flu viruses will spread are usually accurate, sometimes new, unanticipated strains arise. What this means is that some years the vaccine works better than others.

Both a cold and the flu can most often be treated effectively at home with rest, drinking plenty of fluids and over-the-counter pain relief medications such as acetaminophen, ibuprofen and naproxen sodium for fever, headache and body ache. Children should not take aspirin when they have a fever because of its association with Reye’s syndrome. Decongestants can help to ease discomfort from nasal congestion; cough medicine may relieve coughing and sore throat. Talk to your health care provider about which medications are right for you. 

Prescription antiviral medications are available to treat the flu, but need to be started within two days after the first symptoms of the flu appear.

No one wants to spend a week or more sick with a cold or the flu. Tilt the odds in your favor by getting a flu shot and by practicing good infection control habits. If you do become ill, take time to rest and recuperate at home and you will be back to feeling healthy in a matter of days. If symptoms linger or get worse, be sure to see your primary care physician.

Dr. Louks-Smith is a board certified family practice physician at Raiter Clinic in Cloquet.