Flu vs. Cold: How to Tell the Difference

The common cold and the flu are both illnesses that can make you feel bad, but they have different symptoms and severity. The common cold usually causes a runny or stuffy nose, sore throat and mild cough, and the symptoms come on gradually. It's generally mild and doesn't make you feel very sick. The flu, on the other hand, hits you suddenly with a high fever, severe body aches, chills and extreme tiredness. The flu is caused by influenza viruses, which can lead to more serious health issues like pneumonia. While both are caused by viruses and spread similarly, the flu can make you much sicker than a cold. Understanding these differences can help you know what you're dealing with and how to treat it.

What causes a cold and the flu?

Both illnesses come from viruses, but different viruses are to blame.

The common cold is caused by viruses, most often rhinoviruses: 

• Rhinovirus is a type of virus that thrive in the nose and throat, which is why they often lead to symptoms like a runny nose, sore throat, and sneezing.
• These viruses spread through tiny droplets in the air when someone coughs or sneezes.
• You can also catch a cold by touching surfaces with the virus and then touching your face.

The flu is caused by influenza viruses:

• The influenza virus is different from the rhinoviruses.
• It spread through droplets in the air when an infected person coughs, sneezes or talks.
• You can also get the flu by touching surfaces with the virus and then touching your mouth, nose or eyes.

What are the signs and symptoms of a cold and the flu?

Comparing cold symptoms vs. flu symptoms is one of the fastest ways to tell what you're dealing with. Colds tend to stay mild. The flu tends to feel much more intense.

Common cold symptoms:

• Runny or stuffy nose
• Sore throat
• Mild cough
• Sneezing
• Mild headache
• Mild body aches
• Low-grade fever (sometimes)
• Fatigue

Flu symptoms:

• High fever
• Severe body aches
• Chills
• Extreme tiredness or fatigue
• Dry cough
• Sore throat
• Runny or stuffy nose (less common than with a cold)
• Headache
• Sometimes vomiting or diarrhea (more common in children)

How do I know if I have a cold or the flu?

Look at how quickly your symptoms started and how severe they feel. Colds usually come on gradually with mild symptoms. The flu tends to strike suddenly with a high fever, severe body aches and extreme fatigue.

Here's a quick side-by-side comparison to help you tell the difference:

If your symptoms come on fast and feel severe, you're more likely dealing with the flu.

Can a cold turn into the flu?

No. A cold and the flu are caused by different viruses, so one cannot turn into the other. However, it's possible to catch a cold and the flu at the same time, or one right after the other.

How does a cold and the flu spread?

Colds and the flu spread in very similar ways, which is why good hygiene matters so much during cold and flu season.

Both illnesses spread through:

• Tiny droplets in the air when an infected person coughs, sneezes or talks
• Touching contaminated surfaces like door handles, phones, countertops or keyboards and then touching your face
• Close contact with someone who is sick, such as shaking hands

Crowded indoor spaces raise the risk for both, especially the flu. The best protection is frequent handwashing, keeping your distance from people who are sick and avoiding touching your eyes, nose and mouth.

What is the severity of a cold and the flu?

Is the flu worse than a cold? In most cases, yes. The flu tends to be far more severe than a cold and carries a higher risk of complications.

The severity of the common cold:

• Symptoms are usually mild and manageable.
• Typically lasts about seven to ten days.
• Rarely leads to serious complications.
• Most people can continue with daily activities, though they may feel tired.
• Over-the-counter medications can help alleviate symptoms.

The severity of the flu:

• Symptoms are more severe and intense.
• Can last from a few days to two weeks.
• High risk of complications, especially for young children, elderly and people with weakened immune systems.
• Can lead to serious health issues like pneumonia, hospitalization or even death in severe cases.
• Requires rest and sometimes prescription medications to manage symptoms.

What is the treatment for a cold and the flu?

Treatment for both illnesses focuses on rest, fluids and symptom relief, but the flu sometimes calls for extra care.

Treating the common cold:

• Get plenty of rest.
• Drink lots of fluids like water and juice.
• Use over-the-counter medicines for symptoms like a runny nose, sore throat or headache.
• Use a humidifier to help with congestion.
• Gargle with salt water to soothe a sore throat.

Treating the flu:

• Rest as much as possible to help your body fight the virus.
• Drink plenty of fluids to stay hydrated.
• Take over-the-counter medicines to relieve symptoms like fever, aches and congestion.
• Prescription antiviral medicines may be needed if prescribed by a doctor.
• Use a cool mist humidifier to ease breathing.

If you're in a high-risk group, contact your doctor early. Antiviral medications work best when started within the first two days of flu symptoms.

What is prevention for a cold and the flu?

Many of the same habits protect you from both illnesses, but the flu has one extra layer of protection: vaccination.

Everyday prevention for colds and the flu:

• Wash your hands often with soap and water
• Avoid close contact with people who are sick
• Keep your hands away from your eyes, nose and mouth
• Cover coughs and sneezes with a tissue or your elbow
• Use tissues when you cough or sneeze and throw them away immediately
• Clean and disinfect frequently touched surfaces like door handles and phones

Get an annual flu shot

The flu vaccine can lessen the severity of illness in the very young and very old, along with those with conditions such as hypertension, diabetes and chronic respiratory illnesses. Since the flu vaccine can decrease the severity of the illness, particularly those who are medically vulnerable, the flu vaccine can lead to decreased hospitalization and mortality. Getting a flu shot is a personal decision, best made in consultation with a trusted doctor or healthcare provider who understands your unique health profile.  

When should you see a doctor?

Most colds and mild cases of the flu improve with rest and home care. But some symptoms signal that it's time to seek medical attention.

Contact a doctor or seek care if you or a loved one experiences:

• Trouble breathing or shortness of breath
• Symptoms that improve and then suddenly get worse
• A high fever that won't come down
• Signs of dehydration, such as dizziness or reduced urination
• Chest pain or pressure

People in high-risk groups, including young children, older adults, pregnant women and those with chronic conditions, should reach out early. Prompt care can prevent complications and speed recovery.