How to Tell the Difference Between the Cold and Flu

When a respiratory illness leaves you laid up in bed, how can you tell whether it’s a simple cold or the flu? Although these illnesses have similar symptoms, they’re actually caused by different viruses, and the Centers for Disease Control predicts a bad flu season this year. The flu can be dangerous for some people, including young children and pregnant women, so it’s important to know how to recognize and treat it. Read on to find out how to look after yourself and when to see a doctor about a cold or the flu.

What causes colds and the flu? 

Both colds and the flu are viral infections. A virus called influenza causes the flu, but there are multiple varieties of influenza.

Likewise, many different viruses can cause colds, but more than 50% of these minor respiratory infections are caused by rhinovirus. People usually recover from a cold after a few days, without needing to see a doctor.

What is the difference between cold and flu symptoms?

The flu can make you feel terrible and leave you bedridden for a few days, while colds are much milder.

Influenza causes the following symptoms: 

  • Cough
  • Sore throat
  • Runny or blocked nose
  • Aching muscles
  • Feeling tired
  • Headaches
  • Fever
  • Vomiting and diarrhea (most common in children)

Colds cause the following symptoms:

  • Sore throat
  • Runny or blocked nose
  • Sneezing
  • Coughing
  • Headache
  • Body aches
  • Infants may also have a fever, which is unusual in adults

"Symptoms such as a stuffy/runny nose, congestion, sore throat, and cough can overlap," said Celine Thum, M.D., and Medical Director of ParaDocs Worldwide Inc. "Flu symptoms are much more pronounced, [which] can include muscle and joint aches, and extreme fatigue."

Sometimes, it’s difficult to tell whether your illness is a cold or flu. See a doctor if the symptoms drag on for more than two weeks.

How do cold and flu viruses spread?

Cold and flu viruses enter your body through your nose, eyes or mouth. When someone who has a cold or flu coughs or sneezes, droplets of virus spray into the air. When you breathe in these droplets, the virus can infect your body and cause cold or flu symptoms.

Viruses can also spread by contact. If you touch someone who has a cold or flu, and then you touch your face, the virus can enter your nose, mouth, or eyes. You can also catch a cold or flu virus by touching contaminated objects, such as towels or utensils.

What is the incubation period for a cold vs. the flu?

Colds symptoms usually begin one to three days after a virus infects your body.

Flu symptoms typically appear one to four days after infection.

How long will you be sick with a cold or the flu?

On day four of a cold, your symptoms are likely to be at their worst, but you’ll usually start to feel better quickly. Colds usually don't last longer than a week.  

The earliest stage of the flu is usually a fever. In the later stages, you may have a sore throat, cough, runny nose, and muscle aches. Although the symptoms generally become milder after two to three days, the flu can last up to two weeks. You may continue feeling tired and weak for a few weeks after the flu has gone.

How can you prevent catching viruses like colds and the flu? 

Good hygiene can help you to avoid catching a cold or the flu. Follow these tips to stay healthy:

  • Wash your hands frequently with soap and water.
  • Use hand sanitizer when you can’t wash your hands.
  • Avoid touching your face with your hands.
  • Disinfect surfaces such as desks, countertops, and door handles.

There is no vaccine for colds, but getting a flu vaccine every year can protect you against the most common strains of flu that are currently circulating, although you can still catch other strains of influenza. According to the CDC, a flu vaccine can reduce your risk of flu by 50-60 percent.

Who is at highest risk of catching a cold or the flu?

Certain groups of people are more prone to catching colds and the flu. These people are also at risk of developing complications from flu, so it’s important for them to get a vaccine and practice good hygiene. Here's who has the highest risk:

  • Children under 5
  • People aged 65 or over
  • Pregnant women
  • People who have heart or lung disease or a weak immune system

"The flu can be dangerous for people with weak immune systems such as asthmatics, the pregnant and elderly," adds Dr. Thum. "Not only are symptoms worse, but these people can catch other infections while their immune system is hard at work fighting the influenza virus." 

How do doctors diagnose a cold or the flu? 

Doctors don’t use tests to diagnose colds, as patients usually get better by themselves without any treatment. If your cold symptoms don’t improve after a couple of weeks, your doctor may test for other infections.

Doctors can use these tests to diagnose the flu:

  • Rapid influenza diagnostic test: This test gives results in 30 minutes or less, but isn’t very accurate.
  • Laboratory test: A doctor swipes your nose or throat and then sends the sample to a laboratory for testing.

Doctors don’t always use tests to diagnose flu. Often, they make their diagnosis and treatment recommendations based on symptoms.

How are colds and flu treated medically?

Antibiotics are useless for treating colds and flu. Antibiotics only work against bacterial infections, whereas colds and the flu are caused by viruses.

Doctors sometimes prescribe antiviral medications, such as Tamiflu or Relenza, for flu. You need to take these medicines within 48 hours of infection for them to be beneficial.

Most cases of colds and flu don’t require treatment with antivirals. These medications can reduce the symptoms while your body fights the virus:

  • Painkillers (acetaminophen and ibuprofen) 
  • Decongestants
  • Antihistamines

How can you best recover from colds and flu?

The best approach to dealing with a cold or flu is to rest and drink plenty of fluids. Many people find hot drinks and soups very soothing when they have a sore throat. You may also like to stick to soft foods to avoid irritating your throat.

Stay at home, if possible, so you don’t pass your illness on to other people. If you have to be around people, always cough or sneeze into a tissue rather than into the air. Carry hand sanitizer and use it after you touch your face to avoid spreading the infection.

Catching a cold or the flu is annoying, but rarely dangerous. It’s a good idea to get a flu vaccine, particularly if you are in a high-risk group, to protect yourself from the virus. Once you are infected, look after yourself by resting and drinking plenty of fluids. See your doctor if your symptoms don’t disappear within two weeks.

David Barbosa