What? Antibiotics are not for cold and flu? Are you serious?


Sneezing, runny nose, sore throat.

“Oh no! Am I falling ill? I guess I need a course of antibiotics.”

Should one take a course of antibiotics for a cold or flu?

To answer that we need to understand what are antibiotics, cold and flu.

The common cold is a viral infection that is caused by a myriad of different viruses. The most common virus that causes it is the rhinovirus. Symptoms experienced when a person is suffering from the common cold are:

  • Sneezing
  • Coughing
  • Sniffling and runny nose
  • Sore throat
  • Chest congestion

This condition is generally self-limiting and resolves by itself without the need of medications. It typically lasts 3-5 days in a healthy adult.

However, differentiating a cold from flu is the real challenge.


“Wait, what? I always thought cold and flu are the same thing.”

Not so. Flu can be seen as the bigger cousin of cold. It’s nastier and more dangerous. Flu is caused by the influenza virus which mutates very quickly, hence we never really get a chance to be fully immune to it. A person experiencing flu will have the following symptoms:

  • Fever (temperature higher than 37.8ºC)
  • Headache and muscle aches
  • Fatigue
  • Cough and sore throat may also be present

Although symptoms of cold and flu are overlapping, there are some differences (summarized in a table below). Furthermore, symptoms of flu are typically more severe and the patient will appear more ill. The duration of the illness is also longer. It usually lasts between 7 to 14 days. Although flu is also a self-limiting disease, it can be dangerous, causing complications such as pneumonia (infection of the lungs) or even death, especially in young children and the elderly.

cold vs flu

“What are antibiotics then? Are they useful for cold and flu?”

Antibiotics are a group of medications that are used to cure or prevent infections by bacteria. They work by either killing or preventing bacteria from reproducing. Therefore, antibiotics are useless for cold and flu, which are caused by viruses. In fact, using antibiotics for cold or flu will promote bacteria resistance towards antibiotics thereby potentially causing more harm.


“Then why does my doctor prescribe antibiotics when I have symptoms of cold or flu?”

In certain cases, it is difficult to tell the difference between a cold, flu, bacterial infection of the respiratory tract. Your doctor may have seen certain signs, such as pus on your tonsils, or you may have other signs or symptoms suggesting a probable bacterial infection. Hence, your doctor may decide to cover you with a course of antibiotics, just in case. This is up to the professional judgment of the prescriber. However, if your doctor did not prescribe antibiotic for you, please do not pressure them to do so because you most probably do not need it.


“How about antivirals? They kill viruses, right?”

Yes. Antivirals can kill viruses. However, we cannot be sure what type of virus is causing the cold in a particular patient, so we would not be able to select an appropriate antiviral. To find out the causative virus and to select a useful antiviral, expensive tests have to be conducted, and these tests are time consuming. By the time the test results have returned from the laboratory, the patient would have already recovered.

As for flu, the causative agent is the influenza virus. Although this virus has the capability to mutate and avoid our immune system, an antiviral agent called oseltamivir (Brand Name: Tamiflu®) is useful against it. With that said, this agent is rarely used since the disease is self-limiting and the medication merely reduces the duration of infection. Thus, oseltamivir is mainly used in patients who are at high risks of developing complications of flu, such as those who are very young, elderly, immunocompromised, or have other pre-existing diseases. It is also used in patients who have developed complications of flu or those who are severely ill, requiring hospital admission. Similar to antibiotics, overuse of antivirals will promote the development of resistance hence they are not used freely unless indicated.


“I’ve heard about vaccines. Are they useful?”

Unfortunately, there is no effective vaccine against the common cold. There are countless possible viruses that may cause it, and they mutate fairly quickly, thus it is nearly impossible to keep up with them in creating an effective vaccine.

As for flu, there is a seasonal vaccine released yearly that covers three prevailing strains of flu during that season. The flu vaccine is recommended for almost everyone above the above the age of 6 months. Furthermore, it is highly recommended in those who are at risk of developing complications of flu as mentioned above. Even though the flu vaccine is effective against the three prevailing strains of flu for that particular year, it does not prevent a person from contracting flu completely. Mutations in the influenza virus may occur at any time which renders the immunity from the vaccine useless. Moreover, cross species infections, such as avian flu are not covered.

To get vaccinated against influenza, do contact your family doctor for more information.



  1. Sexton D, McClain M. Patient education: Cough, runny nose, and the common cold (The Basics) [Internet]. Uptodate.com. 2017 [cited 9 August 2017]. Available from: https://www.uptodate.com/contents/cough-runny-nose-and-the-common-cold-the-basics
  2. Sexton D, McClain M. The common cold in adults [Internet]. Uptodate.com. 2017 [cited 9 August 2017]. Available from: https://www.uptodate.com/contents/the-common-cold-in-adults-beyond-the-basics
  3. Patient education: Flu (The Basics) [Internet]. Uptodate.com. 2017 [cited 9 August 2017]. Available from: https://www.uptodate.com/contents/flu-the-basics
  4. Hibberd P. Influenza prevention [Internet]. Uptodate.com. 2017 [cited 9 August 2017]. Available from: https://www.uptodate.com/contents/influenza-prevention-beyond-the-basics
  5. Dolin R. Influenza symptoms and treatment [Internet]. Uptodate.com. 2017 [cited 9 August 2017]. Available from: https://www.uptodate.com/contents/influenza-symptoms-and-treatment-beyond-the-basics
Pou Wee Gan
Pou Wee Gan

M.Pharm, MBBS, BCPS, R.Ph

A pharmacist first, then a medical doctor. An avid tea drinker and an occasional poet.


Leave a Comment

Copyright © 2017 Dosing Health. All Rights Reserved. Dosing Health does not provide medical advice, diagnosis or treatment.