Can You Have a Cold and the Flu at the Same Time?

The common cold is no picnic, and the flu can be downright miserable or dangerous. And as those viruses affect so many people, it raises an interesting question: If you're already sick with one, is it possible to catch the other simultaneously? In other words, can a person be sick with both the flu and a cold? And if so, what does that feel like?

During cold and flu season, the two viruses circulate more frequently throughout the United States. Each year, millions of people catch a common cold. Adults have an average of two to three colds per year, and children have even more.

Here's what you should know about the possibility of such an unfortunate predicament and what you can do to protect yourself from becoming ill.

Causes and Symptoms of the Flu and Common Cold

Knowing a little about how and why the two illnesses occur may help explain how catching both viral illnesses at the same time may happen.

There are several types of influenza virus, two of which, influenza A and B, are the typical causes of seasonal flu. In contrast, several viruses can cause the common cold, but the most common culprit is the rhinovirus.

Symptoms of the flu and the common cold are similar, and sometimes, it can be difficult to distinguish between them. Still, there are some key differences.

Flu Symptoms

The flu generally causes symptoms such as:

• Fever
• Chills
• Cough
• Sore throat
• Congestion
• Runny nose
• Muscle aches and pains
• Headaches
• Fatigue

Common Cold Symptoms

The common cold, on the other hand, is generally milder than the flu, with symptoms like:

• Sneezing
• Congestion
• Runny nose
• Sore throat
• Cough
• Headache

Can You Have Two Viruses at Once?

While there’s been plenty of research on the flu and the common cold, few studies focus on the concurrence of both viral illnesses.

But in one study published in 2019 in Proceedings of the National Academy of Sciences of the United States of America, researchers from the University of Glasgow analyzed viral test results of more than 44,000 patients in Glasgow from 2005–2013.

The researchers found that the influenza virus and rhinoviruses, one of the common cold's causes, interact negatively. Per the researchers, the viruses possibly compete with each other, explaining why you don't see many colds during flu season.

But that doesn’t mean it’s impossible to have both illnesses simultaneously, William Schaffner, MD, professor of infectious diseases and preventive medicine at Vanderbilt University, told Health.

"The cold virus spends most of its time up in your nose and your sinuses and the back of your throat," said Dr. Schaffner. "Whereas, the flu virus gets into the back of your throat and has the tendency to get down into your chest."

But they are both respiratory viruses, added Dr. Schaffner, and there's no reason they can't both infect a person simultaneously. The same goes for other causes of cold-like illnesses, such as COVID-19 or respiratory syncytial virus (RSV).

The body can fight two infections simultaneously. Although, the double-whammy may leave you feeling even worse than a normal bout of a cold or flu. 

"You probably wouldn't be able to tell that you have both at once," said Dr. Schaffner. "You would probably just be several degrees more miserable than normal, and you'd have the impression that you've got a really nasty case of the flu."

What About Other Infections?

A more significant concern may be catching a bacterial infection while you’re already sick with the flu. 

For example, a review published in 2017 in Frontiers in Microbiology highlighted the ability of bacterial illnesses, like pneumonia and staph infections, to piggyback onto an existing flu illness. According to the researchers, bacterial illnesses occur afterward or concurrently in as many as 65% of lab-confirmed flu cases. 

According to the researchers, the influenza virus obliges bacterial illnesses in many ways. For example, the flu can weaken your immune system and cause cell destruction, making you more susceptible to bacterial illnesses. Some illnesses, like bacterial pneumonia, can worsen the severity of the flu and other viruses.

Antibiotics can help treat bacterial illnesses. But those drugs come with problems, like overprescription and antibiotic resistance.

How To Protect Yourself

The yearly flu vaccine is key to safeguarding against getting a nasty combination of illnesses during cold and flu season. 

"We don't have any kind of vaccine against the cold. But we do have one for the flu, which of course, is the more serious offender and makes more people very sick," explained Dr. Schaffner.

As with all vaccines, the flu vaccine does not 100% guarantee that you will not become ill. However, the vaccine can reduce your risk of catching the flu and your risk of experiencing serious complications, like bacterial illnesses. 

The flu vaccine provides varied protection between seasons. Age, health status, and the "match" between the viruses in the vaccine and those in circulation also affect the vaccine's effectiveness.

Washing your hands regularly, not sharing utensils or glasses, and avoiding other people who are sick are also essential to protect against the flu and common cold.

And if you come down with an infection, get plenty of rest and fluids to help your body fight the virus.

A Quick Review

While it's not common to concurrently have a cold and flu, it is possible. The good news is that your body can fight two infections simultaneously. However, you will likely feel worse than with a normal illness.

Protecting yourself from the flu by getting the flu vaccine during cold and flu season is essential. Of course, it is also important to avoid germs (and prevent their spread) by washing your hands and not sharing utensils.