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Cold or Flu? How to Tell Whether You Have a Cold or the Flu

You’re tired, you have a headache, a sore throat, and you’re sneezing. Is it a cold? Or is it the flu? Learn how to differentiate between these illnesses.

Cold or Flu? How to Tell Whether You Have a Cold or the Flu

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You're tired, your head aches, your throat's sore, you're sneezing, and you just can't stop reaching for the box of tissues because of that seemingly everlasting runny nose. Is it a cold? Or is it the flu (aka influenza)? It's easy to confuse colds and the flu---their symptoms overlap, making it difficult to figure out which you have. Colds and flu both affect the respiratory system. And both are contagious. However, once you understand the few key differences, you'll be able to make the best treatment choices.

What Causes Colds?

Colds are caused by viruses and affect your nose and throat—the upper respiratory tract. Over 200 viruses can cause the common cold. Rhinoviruses, which cause sinus and ear infections as well as asthma attacks, are the most common. Other cold-causing viruses include adenovirus, respiratory syncytial virus, human parainfluenza viruses, human coronaviruses and human metapneumovirus. The infection spreads mainly by droplets, from person to person through the air and through close personal contact. When an infected person coughs, sneezes or even talks these droplets spread to other people or even objects, like a table, doorknob, towel or toy, which can serve as transmission points for a cold virus. Even contact with stool from an infected person (for example, changing a baby's dirty diaper) can spread a cold virus.

Unfortunately, the common cold is just that—quite common. Each year there are millions of cases of colds in the United States. Adults usually develop 2 to 4 colds annually, mostly during the colder winter months. Kids have it even worse. They normally contract 6 to 10 colds every year, usually by coming into contact with children with colds at grade school, kindergarten or daycare. Colds are the number one reason why adults miss work and kids miss school.

Typical Symptoms of Colds

Colds usually come on slowly, taking a few days to develop. A sore throat may be the first sign of a cold, but not everyone with a cold has this symptom. Sneezing and a stuffy or runny nose usually follow. Coughing, low-grade fever, slight body aches, mild headache and a scratchy throat also can develop. Most people feel better in about 7 to 10 days. People with weakened immune systems, asthma or certain other respiratory problems, such as COPD (chronic obstructive pulmonary disease), make take longer to recover from a cold. Or they may develop serious illness, such as pneumonia or bronchitis.

How to Treat a Cold

There's no cure for the common cold, but plenty of rest and fluids can help. Over-the-counter cold medications can help ease symptoms. Contact your doctor if you develop a fever over 101.3 F, have a fever for more than 5 days, or if a fever returns after a fever-free period. And if you develop shortness of breath, wheezing or severe sinus pain, sore throat or headache, call your doctor.

What Causes the Flu?

Flu is caused by viruses just like colds are, but different types. These are known as Influenza Type A, B and C. Type A is responsible for about 95% of flu cases, with Type B responsible for most of the others. Type C occurs much less frequently, mostly in children. The different strains of each type are further broken down according to the version of two different proteins found on the surface of the virus (for example, influenza A, H1N1).

These contagious flu viruses infect the nose, throat and sometimes the lungs. They can cause mild to severe illness, but sometimes can be deadly. Unlike the common cold, vaccines are developed each year to combat the most likely to occur flu virus for that year. Flu viruses change constantly. If you've had flu at some point in your life, your body has made antibodies against that particular flu strain. In other words, if future flu viruses are like the ones you've already encountered (whether by having flu or a flu vaccination) those antibodies can lessen the flu's severity or even prevent you from becoming ill. Unfortunately, those antibodies can't protect you from new flu viruses that are different from those you've previously encountered. That's why the best defense against the flu is an annual flu vaccination.

Unlike the common cold, which can be contracted throughout the year, flu is seasonal. Peak season usually occurs between December and February, but some flu seasons can begin as early as October and last until May.

Typical Symptoms of the Flu

Unlike the common cold, flu symptoms come on suddenly. Fever (over 100.4 F) or feeling feverish combined with chills, muscle or body aches, cough, sore or scratchy throat, extreme fatigue, headaches, stuffy or runny nose and sneezing are symptomatic of the flu. However, not everyone will experience all of these symptoms, especially fever. Symptoms can last up to 2 weeks.

How to Treat the Flu

Most people who contract the flu can treat their symptoms at home and usually don't need to see a doctor. Plenty of rest and fluids as well as over-the-counter medications can reduce pain and nasal symptoms. Some people, though, are at high risk for developing serious complications if they have the flu. These include children under age 5 (particularly those under age 2), adults over age 65 and people with weakened immune systems, diabetes, asthma or cardiac or kidney disease. Very obese individuals, with a body mass index (BMI) of 40 or greater are also at increased risk, as are pregnant women and residents of nursing homes and other long-term care facilities. Serious complications include pneumonia, bronchitis, ear infections, asthma flare-ups and heart problems.

Rapid flu tests, approved by the FDA are available. If you are at high risk for complications from the flu, you should contact your doctor right away. Prescription antiviral drugs taken within the first 48 hours after the onset of flu symptoms can reduce the flu's severity and help prevent more serious complications. If you're not at high risk for complications, but your flu lasts longer than a week or two or if your symptoms worsen, it's best to check with your doctor. You may have developed a second infection such as bronchitis or pneumonia.

Quick Check Chart

Use the chart below to better understand the differences between what you may experience with a cold versus what you may experience with the flu. While most symptoms are common to both, they don't occur at the same rate or severity. Carefully evaluating which symptoms you have and how bad they are can greatly help you to distinguish between these two respiratory infections. And once you do, you'll be better able to take the appropriate next steps to full recovery.

SYMPTOM COLD FLU
Symptom onset gradual sudden
Fever uncommon common, usually between 100 to 102 F (occasionally higher), lasts 3 to 4 days
Muscle or body aches slight chance, mild if present common, often severe
Chills uncommon, but possible common
Fatigue sometimes, but not severe common
Extreme exhaustion never common, usually at the beginning
Headache uncommon, but possible common
Cough common common, can be severe
Sneezing common sometimes
Sore or scratchy throat common sometimes
Stuffy or runny nose common sometimes
Chest discomfort mild to moderate common


Disclaimer: The article does not replace an evaluation by a physician. Information on this page is provided as an information resource only, and is not to be used or relied on for any diagnostic or treatment purposes.

A.I. Health Assistant

Take a quiz to find out whether you have a cold or the flu.

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