How To Tell the Difference Between Allergies vs. Sinus Infection (Sinusitis)

Allergies occur when your body's immune system reacts to a foreign substance. Some may be "seasonal" when you get them only in the spring or fall, or they may be year-round. Sinusitis or a sinus infection is an inflammation or swelling of the tissue lining the sinuses. A sinus infection usually happens after you've had a cold or allergies. You should seek medical attention if you have trouble breathing; any of the signs or symptoms are particularly severe.
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How to Tell the Difference Between Allergies vs. Sinus Infection
You can tell the difference between allergies vs. a sinus infection by evaluating your symptoms.
Allergies vs. Sinus Infection Symptom Comparison
Symptom | Allergies | Sinus Infection |
---|---|---|
Thick colored mucus | Possible | Likely |
Stuffy nose | Likely | Likely |
Sneezing | Likely | Possible |
Coughing | Possible | Likely (from post-nasal drip) |
Headache | Possible | Likely |
Fever | Not likely | Slight fever possible |
Swollen feeling in your face | Possible | Possible |
Watery or itchy eyes | Possible | Not likely |
Symptom Comparison
If you have allergies, you'll start feeling symptoms soon after coming into contact with the stuff you're allergic to. Your symptoms keep up as long as the allergen still surrounds you. Allergies can occur at any time of year. While some may be "seasonal," which is when you get them only in the spring or fall, or they may be year-round. For instance, an allergy to pets or mold would be a problem no matter the season.
Sinusitis, however, usually happens after you've had a cold or allergies. Some symptoms will linger, even after your cold goes away. You may have a stuffy nose and cough for more than a week or two. There are two kinds of sinusitis: "acute" and "chronic." If your symptoms last less than 4 weeks, it's acute. If they go on for 3 months or longer, you have chronic sinusitis.
What Causes Allergies
Allergies occur when your body's immune system reacts to a foreign substance. Pollen, bee venom, pet dander, or a certain food(s) are the most popular allergies. Your immune system produces substances known as antibodies. When a person has allergies, the immune system makes antibodies that identify a particular allergen as harmful while it isn't.
When in contact with the allergen, your immune system's reaction may cause inflamed skin, sinuses, airways, or digestive system. The severity of allergies ranges from person to person, from minor irritation to anaphylaxis, a life-threatening emergency. Most allergies can't be cured. However, treatments can help relieve your allergy symptoms.

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What Causes a Sinus Infection
Sinusitis or a sinus infection is an inflammation or swelling of the tissue lining the sinuses. Healthy sinuses are filled with air, but when they become blocked and filled with fluid, germs can grow and cause an infection.
Conditions that can cause sinus blockage may include:
- The common cold
- Allergic rhinitis, which is swelling of the lining of the nose caused by allergens
- Small growths in the lining of the nose called nasal polyps
- A deviated septum, which is a shift in the nasal cavity
Treating Allergies vs. Sinus Infection
Allergies
When dealing with allergies, the first thing you may turn to ease the symptoms are decongestants or antihistamines. They're the most common treatments, and they help ease a stuffy or runny nose, sneezing, and itching. Your doctor may also suggest corticosteroids, meds that reduce inflammation.
If you are dealing with seasonal or year-round allergies, a long-term solution may be needed. Some people begin their allergy medication before their allergy season begins.
Some doctors also recommend allergy shots. For around 3 to 5 years, you would receive regular injections of a small amount of whatever kicks off your allergic reaction, similar to how a vaccine works. This will help your body develop an "immunity" and have less and less reaction to your allergy trigger.
Sinus Infection (Sinusitis)
Antihistamines can help treat a sinus infection. You can also try nasal decongestant sprays, but you should use them for only 3-4 days. After that, you could get what's called the "rebound" effect, which means your symptoms start to get worse rather than better in between dosing, so you'll feel the need to use more and more of the decongestant nasal spray.
Another option to consider is nasal sprays that have corticosteroids. However, it can take several weeks to experience the full benefits. Humidifiers, salt-water rinse, or hot packs are other natural solutions that may help your symptoms. If bacteria cause your sinusitis, your doctor may put you on a round of antibiotics. You may take them anywhere from 3-28 days.

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Preventing Allergies vs. Sinus Infection
The best way to prevent allergies is to avoid your allergies. However, sometimes coming in contact with allergens is inevitable. Here are some ways to avoid allergies:
- Take your allergy medication as prescribed
- Know what an allergic reaction looks like and what to do in the event
- Keep your epinephrine auto-injectors with you at all times, if applicable
The best ways to prevent a sinus infection include:
- Frequently washing your hands.
- Keeping the nose moist with nasal saline sprays
- Avoid nasal irritants such as pollution, smoke
- Irrigate your sinuses regularly (from once a day to once a week for some) with a saline sinus wash
When to Seek Medical Attention
Allergies
You should seek medical attention if you are having trouble breathing. Any of the signs or symptoms are particularly severe, such as loss of consciousness or difficulty breathing, or if different parts or systems of the body are involved, such as having the combination of hives and vomiting.
Sinus Infection
You should make an appointment with your doctor if you have a fever, nasal discharge, congestion, or facial pain that lasts longer than ten days or keeps coming back.

Alyssa is a Senior Marketing Associate & Content Writer at Mira. She is passionate about educating others on how to affordably access healthcare.