What is the difference between a cold and an allergy?

UCLA Health
Administration Specialist

A cold is a respiratory infection caused by a virus. An allergy is your body’s response to a substance (trigger) in the environment, such as pollen or dust. Both can cause a stuffy nose and other symptoms. However, colds go away in about 7 to 10 days. Allergy symptoms tend to last longer. Allergy symptoms tend to worsen during certain times of the year when environmental allergens are present.

Symptoms of a cold or flu differ from those of allergies. In this video, Yvonne Braver, MD, of Brandon Regional Hospital describes the main differences between a cold and allergies.
Stacy Wiegman, PharmD
Pharmacy Specialist
The difference between a cold and an allergy starts with the causes of each condition. A cold is an infection caused by a virus. An allergy is the body’s reaction to an allergen, a substance (such as pollen) that your immune system views as an invader. A cold will typically last for a week to 10 days, while an allergy continues for as long as you’re exposed to the allergen. Colds are most common during the winter, but allergies can occur any time—usually in spring and fall. A cold evolves, starting with a runny or stuffy nose, mucus that may turn yellow or green, and a sore throat. An allergy occurs when you’re exposed to the allergen. Your nose runs with clear mucus, you sneeze and your eyes itch.
Sherrie Pierce, DNP
Nursing Specialist

Telling the difference between cold and allergy symptoms can be difficult to distinguish even for health care providers. I explain it to my patients like this:  If it is allergies you will have sneezing, itching, nasal congestion and a clear watery nasal drainage (most of the time). If you have a cold you may have a fever, a more persistent sore throat, cough, general malaise and a thicker mucous but clear runny nose (most of the time). Nasal drainage can sometimes be cloudy or darker, especially in the morning, and this does not necessarily mean you need an antibiotic. Treat cold symptoms with fluids, rest and good nutrition and see your health care provider if symptoms last longer than 7 days or worsen.

Dr. Leigh Vinocur, MD
Emergency Medicine Specialist

Cold symptoms and allergies are somewhat similar. Colds almost always include cough and congestion with a yellowish mucus discharge as well as occasional muscle aches, fatigue and sometimes fever. Most colds usually begin with a sore throat. Allergies symptoms almost never include a fever or sore throat; the most common allergy symptoms are itchy, watery eyes and clear mucus congestion or postnasal drip.

Colds can last anywhere from a few days to 2 weeks, whereas allergy symptoms can last for months. Colds occur in winter months most often, but can occur at anytime. Allergies, especially seasonal ones, usually appear in spring due to flowers and tree pollen, and the fall for grasses. However, mold and dust allergies can occur anytime.

Dr. Peter N. Mattar, MD
Family Practitioner

Differentiating between cold and allergy symptoms can be challenging. Cold symptoms include runny nose, cough, fever at times, head congestion, sore throat, and/or headache. Allergy symptoms include clear runny nose, postnasal drip causing itchy throat, watery itchy eyes, and/or sneezing. Colds last few days to a week, but allergy symptoms can last for months at a time. Although colds and allergies can occur any times, colds usually occur in the winter months while allergies usually peak in the fall and spring.

The difference between a cold and an allergy is that a cold is caused by a virus and allergies often occur in response to irritants like dust mites, pollen or ragweed.
In this video, Tarak Reddy, MD from StoneSprings Hospital Center differentiates between a cold and an allergy and their respective symptoms.
There are many common symptoms of flu and allergies. Brian Hanrahan, MD from Johnston-Willis Hospital shares one major symptom that can help you differentiate between the two.
To tell the difference between a cold or flu and allergies, you look at the onset and the duration. In this video, I will explain that cold and flu symptoms clear up within a week, whereas allergies are chronic.

Continue Learning about Cold and Flu

Cold and Flu

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Colds and flu are both viral infections, but have different symptoms. With a cold you will have symptoms such as a runny nose or a sore throat. Flu symptoms come on suddenly and may include fever, body aches or vomiting. While the...

re is no cure for either, there are treatments -- chicken soup, nasal sprays, rest -- which can help your feel better.

Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.