Also known as sinusitis or rhinosinusitis, a sinus infection is a common condition that affects millions of people each year. Because they resemble highly infectious conditions like the flu, many people believe that they are equally contagious. Ultimately, whether or not a sinus infection is contagious depends on its cause.

Locations of Infection

Sinus infections can occur in a few different locations:

  • Paranasal sinuses near the nose and eyes
  • Ethmoidal sinuses between the eyes
  • Sphenoidal sinus behind the eyes
  • The frontal sinuses above the eyes
  • The maxillary sinuses below the eyes

Because the maxillary cavity is the largest, maxillary infections are the most common type.

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Causes of Sinus Infections

Most sinus infections are the result of a virus, though bacterial infections are also possible. In rare instances, a fungus may be responsible. Other types of infections typically precipitate a sinus infection. For example, conditions like the cold or flu can lead to fluid build-up in the sinuses. This creates a perfect environment for bacteria or viruses, leading to an infection.

woman fluid runny nose tissue PeopleImages / Getty Images


Are Sinus Infections Contagious?

While some debate remains, most experts agree that bacterial sinus infections are not contagious. However, evidence suggests that viral infections can easily spread from person to person. The most common viruses responsible for sinus infections are rhinoviruses, coronaviruses, and influenza viruses. Fungal sinus infections are not contagious, though a fungus-rich environment may cause infections in multiple people.

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How Viruses Travel

Viruses can utilize many means of transmission. Some viruses travel on droplets in the air after someone sneezes, coughs, or breathes. Inhaling these particles can lead to infection. Direct hand contact between people, such as during a handshake, is another method of transmission. Certain viruses can live on inanimate objects, such as doorknobs, for several days. If a person uses the object and then touches their eyes, nose, or mouth, the virus may spread to them.

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Virus Lifespan on Surfaces

Different viruses can survive on an object for varying amounts of time. A study of the rhinovirus discovered it could remain active on an object for up to 48 hours, though the infection rate dramatically fell over that time. Research on influenza viruses found that when infected mucus droplets landed on an object, the mucus kept one virus active for 17 days.

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Chances of Infection

Ultimately, the virus type determines how likely a person is to develop a sinus infection. Some viruses are substantially more powerful or active than others and are more likely to survive long enough to spread. This, along with differences in immune system strength, makes it extremely difficult to predict the risk of a sinus infection.

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Risk Factors

Certain factors dramatically increase the risk of developing a sinus infection. People with nasal allergies, nasal polyps, rare nose structures, or asthma are significantly more likely to have sinus infections. Individuals who smoke may develop sinus infections more often. Underlying conditions like diabetes, HIV, and cystic fibrosis also increase the risk.

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Knowing Symptoms

Recognizing the symptoms of a sinus infection can enable a person to limit and protect against the virus’ spread, through their own body and to others. It can sometimes be difficult to distinguish sinus infection symptoms from a respiratory or similar illness. Facial pain or pressure along with bad breath are the key signs of a sinus infection. Other symptoms include a cough, runny nose, sore throat, and headache.

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Preventing Transmission

Following a few basic protocols can dramatically reduce the risk of viral transmission. Notably, proper and frequent handwashing ensures the virus cannot travel through direct contact. Multi-layer masks can limit the spread of infected droplets, while specialized medical masks can sometimes prevent the spread entirely. Flu and pneumococcal vaccines are also effective.

proper washing hands Moyo Studio / Getty Images



Initial treatment for a sinus infection is watchful waiting. Most people’s bodies can fight the infection without the need for further treatment. If the infection does not improve after several days, the person may require antibiotics. Should any complications arise, doctors will treat those issues directly and on a case-by-case basis. Saline nasal sprays may provide short-term relief.

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