A woman with a sinus infection (sinusitis) blows her nose.

What do 31 million people in the United States have in common every year? According to the American College of Allergy, Asthma & Immunology, sinus infections, also known as sinusitis or rhinosinusitis. Considering how common these infections are, many people wonder if sinus infections are contagious.

The answer is a little more complicated than a simple “yes” or “no.”

There are many causes of sinusitis; depending on the cause, the sinus infection may or may not be contagious. The most common cause of acute sinusitis is a viral infection. In other words, most short-term sinus infections are caused by a virus (also known as viral sinusitis). When a virus is to blame, sinusitis can be contagious. Much less commonly, acute sinusitis can be the result of bacteria; bacterial sinusitis is not contagious.

Transmission: How Do You Get Sinus Infections?

A sinus is a small cavity in the body, specifically in organs or tissues. When most people think of sinuses, though, they are thinking of paranasal sinuses, located in the skull around and connecting to the nose. A sinus infection occurs when these cavities become inflamed.

How does this inflammation occur? There are several potential causes of sinusitis (both acute and chronic), including:

  • Allergies
  • Bacteria
  • Deviated septum
  • Fungi
  • Nasal polyps
  • Nasal tumors
  • Viruses

Viral Sinusitis

A virus is most often to blame for a sinus infection. One of the immune system’s go-to responses to a foreign invader like a virus is inflammation; when this inflammation occurs, mucus in these cavities cannot drain. The result? There’s a buildup of mucus in the sinuses, which can lead to pressure, pain, and infection—aka, a sinus infection. All in all, it’s no wonder that a sinus infection can develop from a viral infection like the cold or flu.

Common colds and the flu are highly transmissible, meaning they are easy to pass from person to person. There’s a reason why moms have always said to cough or sneeze into the elbow; one of the most common ways these viruses spread is through the air when someone coughs or sneezes and doesn’t cover their mouth.

Another common form of transmission is when someone coughs or sneezes into their hands, and then grabs something with their infected hand, like a countertop, doorknob, or light switch. Once the virus reaches these surfaces, it can live there for a short period of time. If someone touches an infected surface, they run the risk of becoming sick themselves. This illness presents the possibility of a sinus infection.

Bacterial Sinusitis

Short-term sinus infections are rarely the cause of a sinus infection. By some estimates, bacterial sinusitis only occurs in roughly 0.5% to 2% of cases, and even then it’s often the complication of a viral infection.

Sinus infections caused by bacteria are not contagious.

Allergic Sinusitis

Allergies may be to blame for other cases of sinusitis. Specifically, a common allergic response is inflammation. This inflammation can prevent mucus from draining out of the paranasal sinuses. Watery eyes, sinus congestion, sneezing, runny nose, and more may develop as a result.

Symptoms

Sinus infection symptoms include:

  • Altered or diminished sense of smell
  • Bad breath
  • Coughing
  • Ear inflammation
  • Facial pain and tenderness
  • Facial swelling
  • Fatigue
  • Fever
  • Headache
  • Itching
  • Nasal congestion
  • Nasal discharge (thick and either green, yellow, or cloudy)
  • Runny nose

How Long Do These Symptoms Last?

How long these symptoms last will vary based on several factors. That being said, acute viral sinusitis typically only lasts 7-10 days. Cases lasting longer are likely the result of bacterial infections, and may require a trip to the doctor for antibiotics.

Chronic sinus infections last at least 12 weeks.

Treatment

Treatment will vary based on what is causing the sinusitis.

For Cases Lasting 7 to 10 Days

Most cases of sinusitis last 7 to 10 days and present only mild symptoms, and the condition will typically improve without the need for a doctor’s visit. In these cases, it’s simple enough to simply treat the symptoms to make these 7 to 10 days easier to manage.

Antihistamines

Antihistamines are the go-to medications for combating allergies, especially runny noses caused by allergies. Why is that, though? Well, the cells in the body release histamine to trigger acute (short-term) inflammatory responses. So, when allergies result in inflammation, an antihistamine can reduce the body’s inflammatory response.

Antihistamines might not always help, though. In some cases, antihistamines can result in mucus drying up too much—hardened, thick mucus is much harder to pass from the body. 

Available over-the-counter (OTC) antihistamines include:

OTC Decongestants

Nasal decongestants are many people’s go-to OTC drug for reducing stuffiness. Decongestants that contain pseudoephedrine typically work by constricting blood vessels (i.e., it fights inflammation and swelling). Once these vessels constrict, it’s easier to pass built-up mucus that was causing congestion in the first place.

OTC decongestants include:

OTC Pain Relievers and Fever Reducers

When pain and fever strike, common OTC medications like acetaminophen (paracetamol, Tylenol) and ibuprofen (Advil, Motrin) may help. Since ibuprofen is a non-steroidal anti-inflammatory drug (NSAID), it may work better for sinus infections.

However, not everyone can take ibuprofen, such as those who are on blood thinners. Conversely, people with severe liver problems should not take acetaminophen. So, it’s always important to ask a doctor which OTC drug they think is best for a patient’s specific situation.

Sleep

If someone needed an excuse to squeeze in some extra Z’s, a sinus infection could be it. After all, rest in one of the primary ways the body heals itself, meaning sleep is crucial to maintaining good health. So, getting a little extra shut-eye during a sinus infection can help the body combat this condition more effectively. This method may be particularly effective for those struggling to relieve sinus pressure.

For Cases Lasting Longer than 7 to 10 Days

For bacterial infections that last longer than 7 to 10 days, it’s important to see a doctor and discuss symptoms. At this point, the doctor may prescribe antibiotics to clear the infection. It’s important to note that antibiotics will only work on bacterial infections, meaning antibiotics will not be effective in treating the vast majority of sinus infections. In fact, taking antibiotics for a viral infection can be harmful as it increases the risk of antibiotic resistance. The result? Future infections will be much harder to treat.

When to See a Doctor for a Sinus Infection

Sometimes sinus infections can pose serious problems and require professional medical attention. People should pay attention to the signs their body is giving them and seek help if they notice that:

  • Symptoms don’t go away after 12 weeks and/or after OTC don’t provide relief
  • Multiple sinus infections occur over the course of a single year
  • Worsening symptoms
  • Symptoms are severe

Severe symptoms include:

  • Confusion
  • High fever (for adults, 102°F to 103°F or 38.8°C to 39.4°C)
  • Persistent, intense headaches
  • Sharp pain in teeth or cheeks
  • Swelling around the eyes or of the forehead
  • Vision problems, particularly double vision

Treating a sinus infection is important, as these infections can lead to complications like:

  • Abscesses
  • Meningitis
  • Osteomyelitis (bone infection)

Final Thoughts

Most sinus infections are caused by a virus, meaning most sinus infections are contagious. Passing on the sinusitis-causing virus to someone else means they can get sick with a cold or flu and even develop a sinus infection themselves.

That all means good hygiene is important, to reduce the risk of both catching and transmitting all sorts of viral infections.

  • Wash hands with soap and warm water for at least 20 seconds
  • Cough or sneeze into the elbow
  • Stay home when sick

The good news about sinus infections is that they typically go away on their own, and people often can manage their symptoms through the use of widely available OTC remedies. Those who notice any of the severe symptoms above or notice that their sinusitis simply will not go away should speak with their doctor.

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