Differences between Common Cold and Flu
Contents
Comparison Article
The common cold and influenza (flu) are both contagious respiratory illnesses, but they are caused by different viruses. Because these two types of illness have similar symptoms, it can be difficult to tell them apart based on physical sensations alone. In general, the flu is more intense than the common cold, and symptoms such as fever, body aches, extreme tiredness, and dry cough are more common and intense with the flu. Colds are usually milder, and people with colds are more likely to have a runny or stuffy nose.
Comparison of symptoms
The following table summarizes common clinical differences between the two conditions as identified by public health organizations such as the Centers for Disease Control and Prevention (CDC).
| Feature | Common cold | Influenza |
|---|---|---|
| Onset of symptoms | Gradual | Abrupt |
| Fever | Rare | Usual; can last 3–4 days |
| Aches | Slight | Usual; often severe |
| Chills | Uncommon | Fairly common |
| Fatigue, weakness | Sometimes | Usual |
| Sneezing | Common | Sometimes |
| Stuffy nose | Common | Sometimes |
| Sore throat | Common | Sometimes |
| Chest discomfort, cough | Mild to moderate | Common; can be severe |
| Headache | Rare | Common |
Viral causes
Over 200 different viruses can cause the common cold. Rhinoviruses are the most frequent cause, accounting for approximately 30% to 80% of cases. Other contributors include human coronaviruses, parainfluenza viruses, and adenoviruses. These viruses affect the upper respiratory tract, primarily the nose and throat.
Influenza is caused by influenza viruses A, B, and C. Type A and B viruses cause the seasonal epidemics of disease that occur almost every winter in the United States. Type C infections generally cause mild respiratory illness and are not thought to cause epidemics. Unlike cold viruses, the flu can affect both the upper and lower respiratory tracts, including the lungs.
Diagnosis and treatment
Because the symptoms of the flu and a cold overlap significantly, clinical diagnosis is often based on the prevalence of the flu in the community. However, healthcare providers can use diagnostic tests to determine if a patient has the flu. These tests, such as the rapid influenza diagnostic test (RIDT) or molecular assays, involve swabbing the inside of the nose or the back of the throat. These tests must be performed within the first few days of illness to be effective.
Treatment for the common cold is primarily supportive. This includes rest, hydration, and over-the-counter medications to manage symptoms like nasal congestion or a sore throat. Antibiotics are not effective against cold viruses and are only prescribed if a secondary bacterial infection develops.
For the flu, antiviral drugs are available by prescription. These medications can shorten the duration of the illness and reduce the risk of complications. They are most effective when started within 48 hours of the onset of symptoms.
Prevention
The most effective way to prevent the flu is to receive an annual influenza vaccine. While there is no vaccine for the common cold, the risk of infection can be reduced through frequent handwashing with soap and water, avoiding close contact with sick individuals, and disinfecting frequently touched surfaces.
