Cold and influenza (flu) - what's the difference?

You are likely to have caught the common cold if you are sneezing a lot and have a bad sore throat as well as a runny or stuffy nose. Feeling feverish, extremely tired and having aches and pains are signs that you may have caught the flu, or influenza.

The terms influenza and the common cold are quite often confused. Influenza (‘flu’ in short) and the common cold (which is often also referred to as ‘flu’ by the lay person) are both respiratory infectious illnesses or airway tract illnesses, but they are caused by different viruses.

Because these two types of illnesses have similar symptoms, it can be difficult (or even impossible) to tell them apart based on symptoms alone. There are special tests to diagnose influenza and these can be ordered by the doctor if deemed necessary.

In general, influenza is worse than the common cold, and symptoms such as fever, body ache, extreme tiredness, and dry cough are more common and intense. A cold is usually milder than influenza. People with a cold are more likely to have a runny or stuffy nose. A cold generally does not result in serious health problems, such as pneumonia, bacterial infections, or hospitalisations.

“People with a cold will usually recover within a week, but influenza may lead to serious complications such as bronchitis and pneumonia, especially among children, older people and those with chronic medical conditions,” says Dr Mark Ng Chung Wai, Family Physician, Senior Consultant at SingHealth Polyclinics​ (SHP) - Outram, a ​member of the SingHealth group.

What causes the common cold and influenza?

Both the common cold and influenza are highly contagious airborne viral infections that attack your upper respiratory tract – your nose, sinuses and throat.

The common cold is caused by a wide variety of viruses, including rhinoviruses, adenoviruses and coronaviruses. Influenza is caused by influenza virus types A, B and C only.

Both the common cold and influenza are transmitted by tiny air droplets which are released when an infected person coughs or sneezes. The viruses are also frequently transmitted through touching your nose and mouth with hands that have come in contact with contaminated surfaces.

Treatment for the common cold and influenza

For the common cold, treatment generally involves rest and medications to alleviate symptoms, whereas there are also anti-viral drugs available for influenza.

Painkillers such as paracetamol and ibuprofen can relieve fever, aches and pain. Decongestants may help ease nasal congestion.

However, if you have a chronic medical condition such as asthma, diabetes and heart disease, you should see your doctor if you experience influenza symptoms.

Is the annual influenza vaccine for everyone?

The common cold is caused by a myriad of viruses that are rapidly changing, so there is no preventive vaccine. On the other hand, a yearly influenza vaccine (commonly called ‘flu shot’) is recommended for everyone from the age of six months onwards, says Dr Ng, who leads the SHP Infection Control & Infectious Diseases Workgroup.

The yearly influenza vaccine is especially recommended for the following high-risk groups of people:

  1. Seniors (aged 65 and above)
  2. Young children (from six months to five years old)
  3. People with chronic illnesses, such as asthma or diabetes
  4. Immunosuppressed patients due to illness or chemotherapy
  5. Residents of nursing homes and patients receiving intermediate- and long-term care services
  6. Pregnant women (all stages of pregnancy)
  7. Healthcare staff in healthcare institutions and establishments

Read on for 5 tips on how to​ prevent the​ common cold and flu​.

Ref: O17​​