Seasonal cold or seasonal allergy: key symptoms and differences

What is the common cold and what causes it?  

The common cold is one of the most frequent respiratory infections, especially during the colder months. It is caused by several types of viruses that mainly affect the nose, throat and sometimes the bronchi. It is easily transmitted when an infected person coughs, sneezes or comes into close contact with others, as the small droplets that are released may carry the virus. 

Early symptoms tend to develop gradually and include nasal congestion, sore throat, sneezing and sometimes a mild cough. In most cases, the cold resolves on its own within a few days with supportive care like rest and proper hydration.  

Allergy: a reaction of the immune system 

Allergic rhinitis—also known as seasonal allergy—causes symptoms similar to those of a cold. However, unlike colds, allergies are not caused by a virus. Instead, they’re the result of an overreaction of the immune system to substances that are usually harmless, called allergens. 

Common allergens include pollen, dust mites, and pet dander from animals like cats and dogs. Exposure to these allergens can trigger an inflammatory response, leading to symptoms such as a runny or itchy nose, repeated sneezing, and often itchy or swollen eyes. 

Why is it so easy to confuse them? 

According to Dr Bartra, they're frequently mistaken because their symptoms can appear almost identical: “Many patients who believe they’re suffering from repeated colds may actually have a respiratory allergy that produces very similar symptoms.” 

However, the underlying cause is different in each case: 

• Colds are caused by the immune system’s response to a viral infection. 

• Seasonal allergies are triggered by the immune system reacting to allergens in the environment. 

While both share symptoms such as sneezing, runny nose and nasal congestion, the context and duration of these symptoms can offer important clues to help tell them apart. 

Main differences that can help distinguish them 

Cough and sore throat: 

People with seasonal allergies rarely experience a sore throat or cough. These symptoms are much more typical of viral infections, which cause inflammation in the throat and irritate the airways. In contrast, in the case of allergic rhinitis, any throat discomfort tends to be mild and typically due to irritation caused by the constant runny nose. 

Fever: 

Fever is another differentiating element. It doesn’t occur to those with seasonal allergies, since there is no infection involved. On the other hand, colds often bring a low to moderate fever—especially during the early days—as the body’s natural response to the virus. 

Itchy or swollen eyes: 

Itchy, red or swollen eyelids—and even dark circles under the eyes due to congestion—are common in seasonal allergies. These symptoms are unusual in viral colds and are a clear indicator of an allergic response. 

When to seek medical advice 

If symptoms last more than two weeks, return each year at the same time, or worsen in particular seasons, it is advisable to consult a healthcare provider. Getting an accurate diagnosis is essential to ensure the most suitable treatment and to improve the patient's quality of life. 

INFORMATION DOCUMENTED BY:

Dr Joan Bartra, Head of the Allergy Department at Hospital Clínic Barcelona.