Allergies occur when your body overreacts to a harmless substance called an allergen. A runny nose, along with other nasal symptoms such as stuffiness or sneezing, is typically caused by allergic rhinitis—commonly called hay fever. Allergies often worsen during certain seasons or with changes in the weather. Learn more about how allergies cause a runny nose and how to treat it in this article.
How Allergies Cause a Runny Nose
A runny nose can be caused by exposure to any allergen, including foods you might be allergic to. However, the most common allergy-related causes of runny nose are allergic rhinitis and sinusitis.
Allergic rhinitis causes a runny nose, stuffiness, sneezing, and itchy skin/eyes/mouth. Although this condition is commonly called hay fever, it doesn’t usually cause a fever. It occurs when your body overreacts to harmless substances in your environment.
You might have “seasonal allergies” that cause your symptoms to worsen during certain seasons, or your symptoms might occur throughout the year—a condition called perennial allergic rhinitis.
Seasonal allergies are caused by environmental airborne allergens. These can include:
Exposure to other specific allergens can also increase symptoms during certain seasons, such as:
- Campfire or fireplace smoke
- Insect stings/bites
- Chlorine in swimming pools
- Pine trees
- Holiday candy ingredients
Allergic rhinitis can also be triggered by indoor allergens or air pollution that aren’t season-specific, including:
- Pet dander
- Dust mites
- Indoor mold
- Cigarette smoke
- Diesel exhaust
- Dry air
A runny nose and post-nasal drip can also be a sign of sinusitis or sinus infection. Seasonal allergies can increase your risk of developing sinusitis. As the fluid builds up in your sinuses, viruses and sometimes bacteria can grow and cause an infection.
Unlike allergies, fever can occur as a side effect of sinusitis. Other symptoms of this condition include:
- Facial pain or pressure
- Sore throat
- Bad smelling breath
How a Sinus Infection Is Diagnosed
Overuse of Nasal Spray
Runny nose allergies can be made worse by one of the things meant to relieve your symptoms—decongestant nasal spray. This phenomenon is called rebound congestion.
Decongestant nasal sprays temporarily decrease nasal symptoms of allergies by reducing swelling in your nasal passageways. They are effective, and tend to work quickly. However, after just a few days of use, the reduced blood flow that helped relieve swelling can start to cause more swelling.
What to Know About Using a Nasal Spray
Treatment & Remedies
There are many treatments available for allergies, including both medications and runny nose home remedies. Effectiveness of these treatments will depend on the severity of your symptoms.
These medications are often the first line of treatment for runny nose allergies. They work by targeting chemicals produced by your immune system that are causing your unwanted symptoms.
Many antihistamines are available OTC, or over-the-counter, (such as Zyrtec, Allegra, Claritin, and Benadryl), while more severe symptoms might require prescription-strength medication. Many cold medicines also contain antihistamines as one of their ingredients.
Staying hydrated provides more than one benefit if you have allergies. First, drinking fluids helps thin out the mucus, making it easier to clear it out when you blow your nose.Second, breathing steam from hot drinks or soups can also open your sinuses and help soothe a sore throat that often occurs as a side effect of allergies.
Breathing warm, moist air can open your nasal passageways and loosen mucus if you have allergies. While this can be done at home using boiling water, it can lead to serious burns.
You can safely breathe some steam just by spending a few extra minutes in a hot shower. Or, try a commercial handheld steam inhaler designed specifically for this purpose. Essential oils, such as eucalyptus, tea tree, peppermint, and thyme can be added to help treat your symptoms.
Rinsing your nasal passageways can help relieve runny nose allergy symptoms by clearing out excess debris and breaking up mucus. This is often done using specialized vessels, such as a neti pot.
Runny nose symptoms can be caused by a variety of non-allergic conditions as well. Nonallergic rhinitis, common cold, and influenza all have symptoms similar to allergies.
Nasal issues can also be caused by a deviated septum, or “crooked nose,” or polyps, which are harmless growths that can occur in your nose.
See your doctor to diagnose the underlying cause of your symptoms. If you have allergies, your doctor might send you to a specialist, or allergist, for testing to determine what you are allergic to. This can provide valuable information to help determine the best treatments.
A Word From Verywell
You don’t have to “learn to live with” your allergies. If OTC medications and home remedies aren’t enough, talk to your doctor. You might benefit from allergy shots or other ongoing medical interventions.
Frequently Asked Questions
Can food allergies cause a runny nose?
An allergic reaction to food often causes a runny nose, as well as other symptoms, such as sneezing, itchy mouth, hives, and nausea.
Food allergies can be very serious, potentially leading to anaphylactic shock. If you are experiencing swelling of the lips, tongue, and throat, seek immediate emergency medical treatment.
What is the best allergy medicine to treat a runny nose?
Runny nose symptoms can be treated effectively with antihistamines and nasal decongestants.
Is it runny nose allergies or is it the flu?
While allergies and the flu both cause a runny nose and have other similar symptoms, there are some differences. The flu often causes a fever, which is not a side effect of allergies. The flu can resolve within a week or so, while allergies can occur over many weeks or even months.
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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
American College of Allergy, Asthma, and Immunology. Common seasonal allergy triggers.
Centers for Disease Control and Prevention. Sinus infection (sinusitis).
American Academy of Family Physicians. Antihistamines: understanding your OTC options.
Horváth G, Ács K. Essential oils in the treatment of respiratory tract diseases highlighting their role in bacterial infections and their anti‐inflammatory action: a review.Flavour Fragr J. 2015;30(5):331-341. doi:10.1002%2Fffj.3252