Is it a Cold or Flu?

Because colds and flu share many symptoms, it can be difficult (or even impossible) to tell the difference between them based on symptoms alone. Special tests that usually must be done within the first few days of illness can tell if a person has the flu.

What is the common cold?

The common cold can be caused by more than 200 different viruses, which easily spread through close contact and in the air from coughs and sneezes. According to the CDC, rhinovirus is the most common type of virus that causes colds.

Most colds clear up within 7 to 10 days. Other illnesses can sometimes follow a cold; these are referred to as called “secondary infections.” The most common of these are bronchitis, pneumonia, sinus infection, and ear infection. Small children are especially prone to ear infections after having a cold.

Cold symptoms

Most people recognize signs of a cold. Most colds will typically begin with a sore throat and runny nose. Typically the symptoms of a cold come on slower and more gradually than the flu.

  • Sore or scratchy throat
  • Tiredness / fatigue
  • Runny or stuffy nose
  • Mild achiness
  • Sneezing
  • Congestion
  • Coughing
  • A mild fever in children (101° F – 102° F)
  • Mild achiness
  • Tiredness / fatigue

Diagnosing a cold

Colds are generally diagnosed by observing symptoms. Tests to identify the virus are not necessary.

Differences between a cold and the flu

Colds and the flu are both viral illness, and sometimes it can be hard to tell them apart. With our helpful chart below, you can learn about cold and flu symptoms and how the symptoms may show up differently for a cold or the flu.


Signs and Symptoms Cold Influenza (Flu)
Symptom onset Gradual Abrupt
Fever Rare Usual; lasts 3-4 days
Aches Slight Usual; often severe
Chills Uncommon Fairly common
Fatigue, weakness Sometimes Usual
Sneezing Common Sometimes
Chest discomfort, cough Mild to moderate; hacking cough Common; can be severe
Stuffy nose Common Sometimes
Sore throat Common Sometimes
Headache Rare Common

The flu (influenza)

Flu is different from a cold, as it usually comes on suddenly. Most people who get flu will recover in a few days to less than two weeks, but some people will develop complications (such as pneumonia) as a result of flu, some of which can be life-threatening if not treated.

Diagnosing the flu

At IMC Immediate Medical Care, our medical team may diagnose you with flu based on your symptoms and their clinical judgment, or they may choose to use an influenza diagnostic test. During an outbreak of respiratory illness, testing for flu can help determine if flu viruses are the cause of the outbreak. Flu testing can also be helpful for some people with suspected flu who are pregnant or have a weakened immune system, and for whom a diagnosis of flu can help their doctor make decisions about their care.