Are Sinus Infections Contagious?

By Sarah Malka, MD
Medically reviewed
August 30, 2021

If you’re an adult in the United States, chances are you’ve dealt with a sinus infection.

Also known as sinusitis, these infections affect approximately 30 million American adults each year.

Sinus infections can be uncomfortable and sometimes painful, with symptoms including nasal congestion, runny nose, sinus pressure, fatigue, fever, and headaches.

But are sinus infections contagious?

That depends on what kind of infection you have. There are three main causes for sinusitis—viruses, bacteria, and allergies.

The most common of the three is a virus, usually a cold or flu. When you have a sinus infection caused by one of these illnesses, you are contagious to those around you.

But you can’t transmit your sinus infection directly: The only illness you would be able to transmit is the cold or flu virus that caused your infection, not the sinus infection itself.

So not everyone who catches the virus from you would get a sinus infection; they might just get general cold or flu symptoms.

Neither bacterial or allergic sinus infections are contagious.

Bacterial sinus infections occur when a person’s nasal passages are blocked for an extended period of time, allowing bacteria to grow. In some cases, allergies can lead to chronic sinusitis, which can last for months. Neither of these can be passed to others. 

The vast majority of sinus infections are viral and will go away all on their own, especially if you’ve had symptoms for less than two weeks.

Bacterial sinusitis usually occurs as a later complication of viral sinusitis. 

In this article, we’ll learn more about how to tell the difference between the three main causes of sinus infections by exploring what a sinus infection is, what causes these infections, and how they spread.

I’ll then discuss common treatments for sinus infections, and when to see a doctor.

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What is a Sinus Infection? 

Located in the forehead, inside the cheekbones, and behind the nose, sinuses are a series of air-filled cavities that surround a person’s facial and nasal passages and help humidify outside air before it reaches the lungs.

The sinus passages can become swollen and inflamed through viral respiratory infections, like colds, or through outside irritation such as allergens, pollution, or cigarette smoke. 

Inflamed sinuses make it harder for mucus to drain out. As a result, fluid pools in the sinuses, causing pain, pressure, and other sinus infection symptoms.

Occasionally, bacteria can grow in this pooled mucous over time, leading to bacterial sinusitis.

Common symptoms of all types of sinus infections include: 

  • Postnasal drip
  • Congestion
  • Pain or swelling in the cheeks or forehead 
  • Fever
  • Runny nose or nasal discharge that looks green or yellow
  • Sore throat
  • Toothache 
  • Bad breath 
  • Consistent cough 
  • Fatigue

What Causes Sinus Infections? 

The most common cause of sinusitis are viral respiratory infections that lead to swelling and irritation of the sinuses, the most frequent being the common cold.

Other ways to contract a sinus infection include: 

  • Nasal polyps, or small growths in the lining of the nose, that may be asymptomatic but block the normal sinus pathways
  • Any structural change to the nasal cavity, such as a deviated septum or history of sinus or nose surgery
  • Hay fever (seasonal allergies or “allergic rhinitis”) causing swelling to the nose’s lining, usually during common allergy seasons

While sinus infections are common and most adults will experience one over their lifetimes, there are outside influences that can lead to more frequent cases of sinusitis.

Risk factors for an increased chance of a sinus infection include:

  • A lasting cold
  • Smoking or exposure to secondhand smoke
  • A broken nose or other structural problems within the sinuses 
  • A weak immune system, or starting the cycle of a new drug that weakens the immune system

How Do Sinus Infections Spread?

Sinusitis generally spreads in the same way a cold or flu does.

Particles and droplets containing viruses become airborne after a person coughs or sneezes, and those germs then spread to others.

These viruses can also be passed by physical touch. Surfaces like doorknobs can become a carrier for a virus if a sick person touches it before a healthy person does.

That’s why actions like washing hands with soap and water, covering your mouth when you cough or sneeze, and avoiding close contact with infected people are important in avoiding getting sick.

But even with the most stringent precautions, sinusitis is common enough that infections still spread fairly easily.

How long are sinus infections contagious? When caused by a viral infection, a person will generally feel symptoms for 7-10 days.

In these cases, they will be contagious with the underlying virus for two weeks, from a few days before they have symptoms until after the symptoms are gone.

Allergic sinusitis, and bacterial sinus infections that occur after a virus, are not contagious to others.  

Treatment

Fortunately, most sinus infections disappear without needing any prescription medication.

The majority will respond well to over-the-counter treatments with time. Without the use of antibiotics, close to 50% of all cases improve within a week, and 70% resolve within two weeks.

There are several ways to help speed up this process with home remedies, while relieving pressure and pain from the sinuses:

  • Applying a warm compress: Place this over the nose and forehead.
  • Using decongestant nasal sprays: These can help drain and dry up the pooled mucous. Use oxymetazoline (Afrin) twice a day for 3 days only (avoid if you have high blood pressure), or fluticasone (Flonase) twice daily for as long as you’re having symptoms.
  • Saline nasal sprays and rinses: These can help clear and thin pooled mucous, preventing bacterial infection and relieving symptoms.  You can use these several times per day.
  • Inhaling steam: This can be done either with a bowl or in a warm shower.
  • Avoiding polluted air, cigarette smoke, or anything else with air contaminants: These can all irritate and inflame the lungs and nasal passages. 
  • Using a humidifier: Adding moisture to the air can provide relief.
  • Drinking plenty of water and resting
  • Using an over-the-counter nasal decongestant: These OTC medications can provide a short-term way to improve symptoms, but should not be used for more than three consecutive days.
  • Taking acetaminophen or ibuprofen with or without an added decongestant: These OTC medications can be effective for sinus headaches and discomfort.
  • Taking Robitussin or Mucinex: Look for the active ingredient guaifenesin. These medicines can help to thin mucus and decrease coughing.

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When To See A Healthcare Provider 

While most sinus infections will go away on their own without antibiotics, some patients will need to see a healthcare provider for prescribed antibiotics or other solutions to beat the infection.

You should seek medical care after experiencing any of the following:

  • Severe headaches or intense facial pain that do not improve with appropriate doses of ibuprofen and acetaminophen and decongestants
  • Symptoms that get worse after initial improvement
  • Symptoms that persist 10 or more days without improvement
  • Fever over 100.4° F lasting longer than three days
  • Fever above 102° F (38.8° C)
  • Problems seeing, double vision, or severe swelling and redness around the eyes
  • Multiple sinus infections over the course of a year

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Frequently Asked Questions

Are bacterial sinus infections contagious?
No. Since they form inside the nose and not through an outside infection, bacterial sinus infections are not contagious. The underlying disease that caused a sinus infection—like a cold or flu—can be contagious, though.
Are sinus infections contagious to babies?
If a sinus infection is caused by a cold or another respiratory virus, that virus could be contagious to anyone who comes in contact with the virus, including babies and young children. But most who are exposed will get cold symptoms, not necessarily a sinus infection.
Are sinus infections contagious if on antibiotics?
Antibiotics help speed up the process of healing if your sinusitis is bacterial. But if your underlying infection is viral, or if you are incorrectly prescribed antibiotics for viral sinusitis, you will still be contagious until the virus goes away. You can possibly be contagious for a few days even before or after showing symptoms. Those suffering from a sinus infection should stay cautious around others for at least three days after the last symptoms have subsided.
K Health articles are all written and reviewed by MDs, PhDs, NPs, or PharmDs and are for informational purposes only. This information does not constitute and should not be relied on for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.

Sarah Malka, MD

Dr. Sarah Malka is a board certified emergency medicine physician with K Health. She completed her residency at Harvard Medical School.