Common Cold vs Flu: How to Tell the Difference

By Arielle Mitton
Medically reviewed
November 9, 2021

Is that runny nose a sign of a cold?

Or could it be the flu?

When you’re feeling run down, it’s easy to wonder what you should do next—and what you can do to feel better fast.

Every year in America, more than 30 million people get the flu.

But the common cold is even more, well, common: Adults average two to three colds per year, and children can have even more.

Both infections are caused by viruses, but colds are usually milder than the flu. Still, it can be difficult to tell the difference.

In this article, I’ll help you figure out if you’ve got a cold or the flu.

I’ll explore the symptoms and causes of both infections, discuss how each is diagnosed and treated, and talk about how they spread.

Finally, I’ll tell you how K Health can help—whether you’ve got a cold or the flu.

Unsure if you have the common cold or the flu? Chat with a doctor today for just $23

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Common Cold and Flu Basics

Both the common cold and influenza are respiratory illnesses.

They are caused by different viral infections, but may result in similar or overlapping symptoms.

  • Common Cold: A general name that may refer to several viruses, the common cold is more likely to be a mild infection. It typically involves sneezing, runny nose, or sore throat without a fever. Colds can happen year-round.
  • Flu: This is the common name for disease caused by strains of one of four main influenza viruses. The flu can occur at any time of the year, but infections ramp up during flu season, which usually lasts from October through May. The peak is often between December and February. While anyone can get the flu, symptoms tend to be worse in people older than 65 or younger than 2, and those who have existing medical conditions like asthma, diabetes, or are pregnant.

Common Cold vs. Flu Symptoms

While both the cold and flu can cause respiratory symptoms, colds tend to be milder.

Influenza more commonly involves fever, even as a mild infection.

A flu infection tends to come on strong, while a cold may build slowly over a few days.

Similarities

Both the common cold and the flu may result in a stuffy nose, sore throat, or cough.

Both viruses may lead to fatigue and weakness, or a general feeling of being run down.

A cough is more common with the flu, but may occur with a cold as well.

Both viruses may cause the following symptoms:

Differences

Influenza infections tend to be more severe than the common cold.

Fevers and chills are more common with the flu, as are body aches.

These symptoms will rarely be seen with the common cold.

However, the flu won’t always cause a fever.

Nausea and vomiting are more common signs of the flu that almost never happen with the common cold.

Children who have the flu may experience vomiting during sickness more commonly than adults.

Headaches are a more frequent symptom of flu infections in both adults and children.

Colds tend to cause more sneezing and congestion, with these symptoms seen less frequently with the flu.

A sore throat is also a common cold symptom that appears less often with influenza.

Common Cold vs. Flu Causes

Both the common cold and flu are caused by viral infections.

The common cold may be caused by one of several viral families that include rhinoviruses, seasonal coronaviruses, or parainfluenza viruses.

Seasonal coronaviruses are not the same thing as SARS-CoV-2, the virus that causes the COVID-19 infection.

It’s not always easy to diagnose the cause of a cold, since there is not a single test to identify every specific virus that may cause symptoms.

Cold infections symptoms tend to last for 7-10 days.

The flu is only caused by influenza viruses.

There are two strains that usually infect humans: influenza A and B. Flu season epidemics are generally caused by either influenza A or B, for which the yearly immunizations are aimed against.

The worst flu seasons tend to be triggered when a new influenza A subtype emerges.

Flu infections typically last 5-7 days.

Common Cold vs. Flu Diagnosis

It is not always possible to diagnose which virus causes a common cold infection.

A doctor may diagnose you with the flu—or tell you that you’ve got a cold—without any kind of tests at all.

But they can run a test to identify whether the cause of your illness is from the flu.

Flu tests may be done in a doctor’s office.

The most common type is a rapid influenza diagnostic test (RIDT), which can return results in 10-15 minutes.

These tests may have a higher likelihood of producing a false negative.

Therefore, even if a flu test is negative, you can still have a flu infection.

The rapid molecular assay, another type of flu test, takes 15-20 minutes to return results, but might be more accurate.

That’s because this kind of test detects genetic material from the influenza virus.

You don’t always have to go into a doctor’s office for a cold or flu diagnosis, and you don’t always need a test.

If your symptoms are mild, a telehealth visit could prevent exposure to other sick patients, but still provide peace of mind for how to proceed.

Common Cold vs. Flu Treatment

Whether you have a cold or the flu, general care can be done at home.

And care for both types of infection involves the same basic steps.

Similarities

Regardless of the cause of your infection, your body will need some extra rest and attention to get back to full strength.

Rest

Whether it is extra sleep or time spent lying down, your body needs more downtime to heal from any type of viral infection.

Aim to get at least eight hours of sleep at night.

Don’t push your body to continue with business as usual. If you’re feeling run down, rest should be a priority.

Hydration

Even when you’re not sick, your body needs to be hydrated to function effectively.

Hydration becomes even more important when your immune system is actively fighting an infection.

Drink plenty of water, clear broth, and juice.

Avoid caffeine, soda, and alcohol, which might worsen dehydration.

Pain Relief

If you’re feeling body aches or have a headache, over-the-counter (OTC) medications like acetaminophen (Tylenol) or ibuprofen (Advil, Motrin) may help.

Aspirin is another OTC pain relief option for adults, but should not be used in children or teenagers for flu-like symptoms.

No matter which pain reliever you choose, follow proper dosage instructions.

Nasal Sprays and Washes

Feeling stuffy and congested can be irritating.

If your nose won’t seem to clear, you can try saline nasal sprays or NETIPOTs that work as decongestants.

They should not be used for more than a week, though, or they could lead to consistent irritation of the nasal membranes.

If using a NETIPOT, be careful to clean it regularly and use the correct source of water.

Cold & Flu Medication

There are many OTC options for taking care of your nasal, cough, or headache symptoms at home.

Some cold and flu medications address all of these at the same time, while others might work as antihistamines, decongestants, cough suppressants, or pain relievers.

You can ask a pharmacist or doctor for guidance on which OTC medication will work best for you.

Differences

There are no medications that can cure the common cold, but there are some drugs that may help treat the flu.

Antiviral drugs may be able to shorten the duration of sickness by 1-2 days in certain populations if taken early enough.

They may also be effective at preventing serious illness or complications in people at higher risk, like those who have compromised immune systems.

Antibiotics are not effective against the common cold.

They also can’t treat or prevent any type of influenza.

They may be used if you develop a secondary bacterial infection.

This happens more often with the flu versus a cold.

Bacterial sinus or ear infections may happen after a flu infection, and require antibiotic therapy,  but not all ear pain is due to bacterial ear infection.

Sinus congestion can also cause referred ear pain that doesn’t respond to antibiotics.

Pneumonia is a less common, but more serious, infection of the lungs that may happen as a result of the flu.

There are some myths that vitamin D, vitamin C, or zinc can prevent illness.

Some research does show that zinc lozenges might be able to shorten the duration of certain cold symptoms if taken as soon as you notice symptoms.

Common Cold vs. Flu Spread

Since both the common cold and the flu are viral respiratory infections, they spread in similar ways.

Both are highly contagious.

Similarities

Both the flu and the common cold viruses spread via droplets in the air or, less frequently, on surfaces that become contaminated by someone who is ill.

You are at highest risk of exposure with close contact—within 6 feet of an infected person.

With cold and flu viruses, people tend to be more contagious the day before they start showing symptoms, and for up to one week after getting sick.

Immunocompromised people and younger children might be able to spread viruses longer, which is why outbreaks tend to be common in daycares and schools.

If you are around someone who has noticeable symptoms of a cold or the flu, you are also at risk of getting sick.

Avoiding exposure is the best way to prevent illness, but you can also lessen your risk by practicing good hygiene:

  • Wash your hands thoroughly, for at least 20 seconds, with soap and water
  • If you can’t wash your hands, use alcohol-based hand sanitizer
  • Don’t touch your face
  • Wear a face covering when indoors

Differences

There are currently no vaccines that can prevent the common cold, but influenza vaccines are available.

Flu vaccines are recommended for everyone 6 months and older to help prevent the spread of influenza.

The flu vaccine may also be  help reduce the likelihood of serious infection or complications, especially in vulnerable populations.

By getting a vaccine, you can reduce your chances of severe illness or of spreading it to others who may have more adverse effects.

The flu vaccine, or flu shot, works by introducing inactive versions of several flu strains to the immune system, so it can develop antibodies to fight against the infection with influenza later on.

U.S. flu shots are quadrivalent vaccines, which means they protect against four types of flu viruses: two influenza A viruses (including H1N1) and two influenza B viruses.

The strains included in the shot change each year based on research about which strains will be most likely to circulate that year. 

Flu vaccine effectiveness varies by flu season, but studies show that they reduce the risk of illness by 40-60% in the general population.

To work best, you should be vaccinated before flu season starts.

Flu vaccines become available starting in the summer before flu season begins.

Even if you still get the flu after receiving a vaccine, research shows that getting the shot is associated with a 26% lower risk of being admitted to the ICU and a 31% reduced risk of death.

Try to get your flu shots before the end of October to be protected for the flu season, however, even if you don’t get it until November or December, it is still worth getting!

How to Prevent the Common Cold and Flu

You can’t prevent the cold or the flu entirely, but you can reduce the likelihood that you’ll get sick by some common sense practices.

The flu vaccine is the best way to reduce your risk of getting the flu.

Other methods of prevention include:

  • Frequent hand washing
  • Not touching your face
  • Disinfecting surfaces, including commonly touched places like your smartphone, steering wheel, keys, doorknobs, appliance handles, and cabinets
  • Not sharing cups, utensils, and dishes
  • Avoiding contact with those who are sick
  • Wearing a face covering when indoors

If you are sick, you can reduce the chance of transmitting illness to others by staying home when you’re ill, frequently washing your hands, and covering your mouth and nose when you sneeze or cough.

Don’t shake hands or touch others, and disinfect surfaces that you touch.

Unsure if you have the common cold or the flu? Chat with a doctor today for just $23

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When To See a Doctor

It’s important to keep your doctor informed about your symptoms and recovery.

If xf cold or flu symptoms take longer than 10 days to resolve, or you start to feel worse or have problems breathing, you should seek immediate medical care.

How K Health Can Help

Many cold and flu infections don’t require a trip to the doctor’s office, but if they do, it can be a struggle to leave the house when you’re already feeling worn out from illness.

You can schedule a visit with a K Health primary care doctor via our app—and talk to a healthcare provider without leaving home.

Download K to check your symptoms, explore conditions and treatments, and if needed text with a doctor in minutes.

K Health’s AI-powered app is HIPAA compliant and based on 20 years of clinical data. If needed, your K Health doctor can order tests or recommend next steps to ensure that your healthcare needs are addressed.

Frequently Asked Questions

Can you have a cold and the flu at the same time?
Yes, it is possible to have multiple viral infections at the same time, including a cold and the flu. However, it is not common. Some evidence even finds that having an influenza virus reduces the ability to catch a cold that is caused by a rhinovirus infection.
Will a cold go away on its own if not treated?
Yes, most cold viruses do not require treatment. In fact, for most colds, there is nothing that can shorten the duration of illness. If you are sick for longer than 7-10 days or your symptoms are not improving, you should see a doctor since it’s possible that your symptoms could be caused by a different virus.
Can the flu lead to a bacterial infection?
Yes, influenza viruses can lead to secondary bacterial infections, most commonly caused by Streptococcus pneumoniae, Haemophilus influenzae, and Staphylococcus aureus. Sinus infections or ear infections are most common, but bacterial pneumonia can occur as well. It’s important to keep your doctor apprised of your symptoms to get treatment if needed.
K Health articles are all written and reviewed by MDs, PhDs, NPs, or PharmDs and are for informational purposes only. This information does not constitute and should not be relied on for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.

K Health has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical associations. We avoid using tertiary references.

Arielle Mitton

Dr. Mitton is a board certified internal medicine physician with over 6 years of experience in urgent care and additional training in geriatric medicine. She completed her trainings at Mount Sinai Hospital and UCLA. She is on the board of the Hyperemesis Research Foundation to help women suffering from hyperemesis gravidarum.