How to Tell the Difference Between the Flu and a Cold

How to Tell the Difference Between the Flu and a Cold

Symptom Watch: Do You Have the Flu or a Cold?

Are you worried by what’s causing your fever and body aches? Is it a cold or the flu? Learn which symptoms likely mean you have the flu and which ones point toward a cold.

ou wake up one morning feeling stuffed-up and achy. You must be starting a cold. Or, maybe it’s the flu.

It can be tricky or even impossible to tell the difference between symptoms of a cold or another virus and the flu. Cold and flu viruses have a lot of symptoms in common. But, flu symptoms are often more severe and usually come on more suddenly.

Causes of the flu and cold

The flu is a moderate to severe illness that affects the whole body and lungs. It is caused by strains of the influenza type A, type B or type C virus (though type C is rare). For example, you have probably heard that the swine (H1N1) flu is also called H1N1 flu. Swine flu is a strain of influenza type A.

Flu strains are constantly mutating or changing. The strain that affects people this season will be different from last year’s virus. It’s important to get the flu shot each year, so your body can fight off this season’s strain. Severe bouts of the flu can lead to more serious health issues like pneumonia or bacterial infections.

The common cold sends more people to the doctor each year than any other illness. A cold is a mild infection that affects the nose and throat. It can be caused by more than 200 different viruses. Rhinoviruses cause the most colds. Adults get an average of two to four colds each year, and children can suffer from six to eight each year. The flu shot will not protect you from a cold. A cold can sometimes lead to an ear or sinus infection.

Timeline and severity of your illness

Knowing when your symptoms occur and how long they last can help clue you in to whether you have a cold or the flu.

Cold. You’ll probably feel the worst two to three days after you get sick. Symptoms last about seven to 10 days, but some can linger for up to three weeks:

Early symptomsLater symptoms
Sore or scratchy throat (often the first symptom) Sneezing Headache ChillsStuffy or runny nose Cough Malaise – a general feeling of being uncomfortable or not feeling well

Flu symptoms usually come on suddenly and more severely. People often compare the flu to being “hit by a truck.” Symptoms last about a week but can sometimes last up to three weeks:

  • Fever (usually only lasts three to four days)
  • Cough
  • Headache
  • Sore throat
  • Muscle aches and pains
  • Weakness
  • Loss of appetite

Cold vs. flu symptoms

Many people mistake the flu for a cold and vice versa. This is no surprise because both viruses share many symptoms. Use this chart to compare the symptoms of a cold and the flu:

FeverRare. Low-grade fevers (lower than 100 degrees F) may develop. Fevers linked with a cold are seen in children more often than adults.Common. Fever is usually higher than 101 degrees F.    
Aches and painsRare. If they occur, they’re usually mild.Common. Can come on suddenly and be severe.
Exhaustion and weaknessRareCommon. Extreme fatigue can last for weeks. Call your doctor if you feel sudden weakness or fatigue.
CoughPossibleHacky, dry cough is common. Call your doctor if you have: Chest pain when coughing or taking a deep breath. Green, bloody or rust-colored mucus that comes up with your cough. Or, if you have mucus that becomes thick or changes in color.
Diarrhea or vomitingRareSome with swine flu have diarrhea and vomiting. Call your doctor if you have severe vomiting or signs of dehydration.
Stuffy or runny noseCommonPossible
Sore throatCommonCommon
Loss of appetiteCommonCommon

Are you still having trouble figuring out if you have a cold or the flu? Keep this in mind:

  • If you have a dry, hacking cough and a fever, you may have the flu.
  • Doctors can’t always tell the difference between a cold and the flu either, based on symptoms. But treatment is generally the same for both, so testing is often not done. Only a lab test can confirm if you have the flu or not.
  • Treatment for both viruses is the same: rest, drink plenty of fluids and consider taking an over-the-counter medication to ease your symptoms.

If you have flu symptoms and are pregnant, age 65 or older, have a chronic medical condition such as heart disease, asthma or diabetes or have a weakened immune system – from HIV or cancer, for example – call your doctor right away. You are at a higher risk for more severe illness and complications from the flu. Your doctor may prescribe an antiviral medicine to help keep you from getting these complications.

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