The common cold and flu are viral infections of the upper respiratory tract, which comprises the nose, mouth, sinuses, and throat. They are among the most common illnesses affecting humans today. So common, in fact, that they are often self-diagnosed and treated at home.
The viruses responsible for both infections are vastly different. The flu is only caused by influenza viruses, whereas the common cold can be caused by over 200 kinds of pathogens. Rhinoviruses, coronaviruses and influenza viruses are the three most common agents accounting for colds. These viruses are all transmitted through direct and indirect contact with the face, where germs reach the mucous membranes lining the nostrils, eyes, and mouth. From there, the viruses can enter the body and multiply. They may even spread to the lower respiratory tract to infect the windpipe and lungs.
Symptoms appear shortly after the infection. Although the common cold and flu share several symptoms, flus are typically more severe.
Table 1. Symptoms of common cold vs. flu
| Common Cold | Flu |
| Runny noseStuffy noseSneezingRaspy coughSore throatMild body acheLittle fatigue | FeverChillsRunny noseStuffy noseSevere raspy/hacking coughSore throatMuscle or chest painCommon headachesFatigueVomiting or diarrhea (more common among children) |
The common cold has milder symptoms and is generally harmless in the long run. Conversely, flu symptoms are more intense and can lead to serious health complications without proper treatment, especially for children under five years of age, seniors over sixty-five, pregnant women, and individuals with chronic medical conditions. For example, the flu can lead to sinus and ear infections, pneumonia, respiratory failure, and inflammation in the heart, brain, or muscle tissue. Telltale signs that distinguish the flu from a cold include shortness of breath, severe muscle pain, little to no urination, and extreme lack of energy. While fevers are more typical of the flu, mild fevers can occasionally occur with the cold for young children.
The most effective treatment for both illnesses is rest. Colds generally resolve within seven to ten days with sufficient rest and fluid intake. Individuals with the flu benefit from the same treatment, but may additionally receive an annual flu vaccine to help prevent future infections. Over-the-counter medications can also relieve symptoms. To avoid catching a cold or flu in the first place, individuals should wash their hands regularly, avoid touching their face in public, stay away from people who are sick, and filter the air in their home if possible.
In summary, the common cold and flu are among the most common viral infections affecting the nose, throat, and lungs. Understanding the similarities and differences between these two illnesses can help individuals take better preventative measures and respond more effectively when symptoms arise.
References
Eccles, Ron. “Understanding the Symptoms of the Common Cold and Influenza.” The Lancet Infectious Diseases, vol. 5, no. 11, Nov. 2005, pp. 718–25, https://doi.org/10.1016/s1473-3099(05)70270-x.
Eccles, Ronald. “Mechanisms of Symptoms of Common Cold and Flu.” Birkhäuser Basel eBooks, 2009, pp. 23–45. https://doi.org/10.1007/978-3-7643-9912-2_2.
“Cold Versus Flu.” U.S. Centers For Disease Control And Prevention, 8 Aug. 2024, www.cdc.gov/flu/about/coldflu.html.
“Signs and Symptoms of Flu.” U.S. Centers For Disease Control And Prevention, 26 Aug. 2024, www.cdc.gov/flu/signs-symptoms/index.html.
Government of Canada. “Flu (Seasonal Influenza): Symptoms and Treatment.” Government of Canada, 9 Dec. 2025, www.canada.ca/en/public-health/services/diseases/flu-influenza.html.
Allan, G. Michael, and Bruce Arroll. “Prevention and Treatment of the Common Cold: Making Sense of the Evidence.” Canadian Medical Association Journal, vol. 186, no. 3, Feb. 2014, pp. 190–99, https://doi.org/10.1503/cmaj.121442.
“Common Cold.” Cleveland Clinic, 7 Feb. 2023, my.clevelandclinic.org/health/diseases/12342-common-cold.