Why It's Unlikely To Have a Cold and the Flu at the Same Time

You can have a cold and the flu at the same time, but researchers say it's unlikely. A study published in 2019 found that these viral infections interact negatively, meaning one may protect against the other.

A cold is typically caused by rhinovirus, while the flu is caused by influenza viruses. You may catch both of these viruses at the same time, but it can be difficult to tell the difference. Both colds and the flu cause similar symptoms, including coughing, headaches, a runny nose, and sore throat.

The two viruses circulate more frequently throughout the United States during cold and flu season. Millions of people catch a common cold each year. Adults have an average of two to three colds per year, and children have even more. Read on to learn whether it's possible to have both a cold and the flu at the same time and how to protect yourself against both.

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

There's been plenty of research on colds and the flu, but few studies focus on the concurrence of both viral illnesses. In a study published in 2019, researchers analyzed viral test results of more than 44,000 people in Glasgow from 2005 to 2013.

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

This doesn't mean it's impossible to have both illnesses simultaneously. "The cold virus spends most of its time up in your nose and your sinuses and the back of your throat," William Schaffner, MD, professor of infectious diseases and preventive medicine at Vanderbilt University, told Health. "The flu virus gets into the back of your throat and has the tendency to get down into your chest."

Both are respiratory viruses, 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, but it may leave you feeling even worse than a normal bout of a cold or the flu. "You probably wouldn't be able to tell that you have both at once. 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," said Dr. Schaffner.

Causes and Symptoms

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. Several viruses can cause a cold, but the most common culprit is rhinovirus.

Cold and flu symptoms are similar. It can be difficult to distinguish between them, but some key differences exist.

Flu Symptoms

The flu generally causes symptoms like:

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

Cold Symptoms

Colds, on the other hand, are generally milder than the flu. Symptoms include:

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

What About Other Infections?

A more significant concern may be catching a bacterial infection while you're already sick with the flu. A review published in 2017 highlighted the ability of bacterial infections, like pneumonia and staph infections, to occur at the same time as the flu. Bacterial infections occur afterward or concurrently in as many as 65% of lab-confirmed flu cases.

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

Antibiotics can help treat bacterial infections. These drugs come with risks, including overprescription and antibiotic resistance.

How To Protect Yourself

The yearly flu vaccine is key to safeguarding against getting a combination of infections during cold and flu season. Like other vaccines, the flu shot doesn't guarantee you won't become ill. The vaccine can still reduce your risk of catching the flu and experiencing serious complications like bacterial infections.

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 its effectiveness.

Other ways to protect against colds and the flu include:

• Avoiding close contact with others if you or they are sick
• Cleaning and disinfecting frequently touched surfaces and objects
• Covering your mouth and nose when you cough or sneeze
• Not touching your face, nose, or mouth without washing your hands
• Staying home if you're sick
• Washing your hands regularly

If you catch a cold or the flu, make sure to get plenty of rest and fluids. These home remedies can help your body fight off the viruses and recover.

A Quick Review

It's not common to concurrently have a cold and flu, but it's possible. The good news is that your body can fight two infections simultaneously. You'll 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. It's also important to avoid germs and prevent their spread by washing your hands and not sharing personal items like utensils.