When Is a Sinus Infection Serious?

Find out how you can tell the difference between a viral and bacterial sinusitis – plus what to do if you suspect an infection.

Sanaz Majd, MD
3-minute read
Episode #125

I’ve been seeing a big surge of viral upper respiratory infections. There was a peak in the usual winter season, but suddenly patients are filing into my waiting room one-by-one, sniffling and coughing. Some who say they “never get sick” may understandably get a tad panicked when experiencing a few days of nasal congestion (those cold gurus who get exposed frequently already know the drill). I don’t blame them – how do you know it’s serious when you rarely get sick in the first place? 

When Is a Sinus Infection Serious?

So I decided to devote today’s episode to acute sinusitis to really help patients delineate what is simply a viral-common-cold-nasal-congestion-thing and what is a true bacterial sinus infection.

What is Acute Sinusitis?

Sinuses are the little pocket holes inside your facial bones that have a connection to your nose. Sinusitis refers to the inflammation of those pocket holes and nasal passages. In fact, as a general rule, any term in medicine that ends in “-itis” refers to inflammation. For instance, bronchitis is inflammation of the bronchials (upper lungs), colitis is inflammation of the colon, bursitis is inflammation of the bursa surrounding joints, etc.

What Causes Sinusitis?

  • Viruses: By far the most common causes of inflammation in the sinuses are viruses that cause the common cold. Viruses are notorious for causing nasal congestion (and runny noses), and hence, inflammation of the sinuses. These nasal symptoms can take 7-10 days to resolve on their own, and often worsen daily until reaching peak discomfort on the 4th or 5th day. The illness begins to improve gradually daily after that. With the common cold, most patients have some improvement after 7-10 days (although they may not be 100% back to their normal baseline state).

See also: What Is the Flu Virus?


  • Bacteria: Bacterial sinusitis can occur when fluid collections within the sinuses don’t drain well, like after the common cold that commonly causes this fluid overload. Then bacteria begin to grow in these moist, wet, fluid-filled sinus pockets. This typically happens after the 7-to-10-day timeframe of the common cold.

Symptoms of Bacterial Sinusitis

Most patients who develop a bacterial sinusitis after a cold describe their nasal congestion improving sometime between the 5th and 10th day, and then boom, all of a sudden get severe facial pain. Again, the timing is very important, as sinusitis does not develop within the first 7 days after a viral infection.

Sinus infections may cause the following symptoms:

  • Facial pain or pressure, may be worse with bending forward

  • Thick nasal discharge

  • Tooth pain

  • Fevers

  • Ear discomfort or clogging sensation


Please note that all content here is strictly for informational purposes only. This content does not substitute any medical advice, and does not replace any medical judgment or reasoning by your own personal health provider. Please always seek a licensed physician in your area regarding all health related questions and issues.

About the Author

Sanaz Majd, MD

Dr. Sanaz Majd is a board-certified Family Medicine physician who graduated from Drexel University College of Medicine in Philadelphia. Her special interests are women's health and patient education.