The overlap in symptoms between the common cold and COVID-19 makes it challenging to determine the cause of illness without a laboratory test. Both conditions are caused by respiratory viruses that circulate widely, especially during cooler months. Understanding the subtle differences in symptom presentation, illness timeline, and severity is the primary way to gain clarity before seeking a professional diagnosis. This article provides a comparative guide to help distinguish between these two common infections.
Symptoms Shared by Both Illnesses
A number of upper respiratory symptoms are common to both the common cold (typically caused by rhinoviruses) and COVID-19 (caused by the SARS-CoV-2 virus). Both illnesses frequently present with a cough, which can range from mild to moderate in intensity. A sore throat is also a common early indicator, often described as a scratchy or painful sensation. Congestion and a runny nose, hallmarks of a typical cold, are also often reported by individuals infected with SARS-CoV-2. Additionally, a general feeling of being unwell, known as malaise, may be present in both cases.
Key Differentiating Symptoms
While many symptoms overlap, certain indicators are more characteristic of one illness, offering clues for differentiation. The sudden, profound loss of taste or smell (anosmia/ageusia) remains a distinguishing feature of COVID-19, often occurring without significant nasal congestion. In contrast, the common cold rarely causes a complete loss of these senses; any reduction is typically a result of severe nasal blockage. Shortness of breath or difficulty breathing is another differentiating symptom for COVID-19, which is uncommon with the common cold. Cold symptoms are generally confined to the upper respiratory tract, whereas COVID-19 often involves systemic issues like significant muscle aches (myalgia), persistent headache, and severe fatigue. A COVID-19 cough is often described as a dry, continuous cough, which can be more forceful than the typically milder cough associated with a cold.
Illness Progression and Severity
The speed and trajectory of the illness can provide insight into the likely cause. Common cold symptoms typically appear gradually, slowly building over one or two days before reaching a peak and then resolving within a week to ten days. Colds rarely involve a fever, and if one is present, it is usually low-grade and brief. Conversely, the onset of COVID-19 symptoms can be more abrupt, and the illness often has a more volatile course, sometimes worsening or fluctuating over a longer period. A high or persistent fever is a much more frequent occurrence with COVID-19, reflecting the body’s more aggressive systemic response to the virus and potentially causing more severe disease, particularly in those with underlying health concerns.
When to Seek Testing
Because of the extensive symptom overlap between the common cold and COVID-19, relying solely on symptom comparison is not a definitive diagnostic method. The most reliable way to confirm the illness is by taking a test, which is particularly important in specific circumstances. If any of the key differentiating symptoms, such as the loss of taste or smell or shortness of breath, are present, testing should be sought immediately. Even if the symptoms are mild and resemble a cold, testing is recommended if there has been a known exposure to someone with COVID-19. In cases of exposure without symptoms, experts suggest waiting at least five full days before taking a test to ensure the virus has reached detectable levels. Testing is also advisable before gathering with individuals who are at a higher risk for severe illness, such as the elderly or those who are immunocompromised.
Testing Options
Testing options generally include rapid antigen tests, which provide quick results but are less sensitive, and PCR tests, which are highly accurate but take longer for processing. If an at-home rapid test is negative but symptoms continue, repeating the test 48 hours later or seeking a more sensitive PCR test is a prudent next step.