Sinus Infection Symptoms, Types, & Causes

Sinus Infection Symptoms: When to Contact a Doctor

Your head is filled with a series of interconnected holes and cavities known as sinuses. The largest of these cavities measure up to an inch across, though others are smaller. The main sinuses include:

  • The maxillary sinuses, which are located behind your cheekbones
  • The frontal sinus, found low in the center of your forehead
  • Ethmoid sinuses, located between the eyes
  • Sphenoid sinuses, located just behind the ethmoid sinuses

Even experts aren’t sure of the exact purpose of sinuses. They may help filter and humidify air through structures called turbinates. Others say the sinuses help to amplify your voice or protect against facial trauma.

Unfortunately, as necessary as they are, your sinuses are warm and moist, making them the ideal environment for potential infections. Let’s take a closer look at the types and symptoms of sinus infection.

What is a Sinus Infection?

Each of your sinuses connects to the nasal airway via a tiny hole called the ostium. Each cavity is lined with a thin, soft tissue called the mucosa. Sinus infection, scientifically known as sinusitis, is an inflammation or swelling in the mucosa.

Other than some mucus, the sinuses are meant to be empty. When they fill with fluid, the sinuses become a breeding ground for potential infections. Blocked sinuses or the ostium can also prevent bacteria from properly draining either out of your nose or down your throat.

Causes of Sinusitis

Sinus infections can be caused by bacteria, viruses, and fungi trapped in the sinuses by anything that interferes with the general flow of air in your sinuses and the drainage of mucus. Some of the most common causes of sinus infections include:

  • The common cold – A common cold can cause swelling in the nasal tissue, leading to inflammation in the sinuses that then blocks the holes that would normally allow for drainage.
  • Allergies – Similar to the common cold, severe seasonal allergies can cause inflammation that blocks nasal passages to prevent proper draining.
  • Bacterial infections – While they’re rarely the cause of initial infections, bacteria can sometimes complicate existing infections and create secondary infections. Bacteria exist even in healthy individuals and are just waiting for the right opportunity to grow and invade. The most common bacteria that cause sinus infections are Streptococcus pneumoniae and Haemophilus influenzae.
  • Tissue irritants – This comprises anything put into the nose or breathed in that causes irritation to your nasal tissues, like cigarette smoke and airborne pollutants. Excessive use of certain over-the-counter nasal sprays can also irritate nasal tissue.
  • Nasal polyps – Nasal polyps are benign growths that develop from sinus or nasal tissues. Polyps can also block nasal passages with the bonus effect of causing headaches by restricting airflow.
  • Anatomy – Some people also just happen to be born with an inclination for sinus infections thanks to certain anatomical abnormalities, including cleft palates and narrow drainage passageways. A deviated septum, wherein the center wall between your nostrils (a structure known as the septum) is severely shifted to one side, is a common cause for chronic sinus infections. Enlarged adenoids, which are masses of tissue found behind the nasal cavity, can also lead to consistent sinus infections.
  • Dehydration – From weather to diseases (like cystic fibrosis) to certain medications (like antihistamines), your sinuses may suffer from a lack of moisture. Aside from the general irritation this poses, dry conditions cause a drying and thickening of mucus secretions. This can lead to more blockages, which only makes it harder for your nose and sinuses to drain properly.
  • Tooth infection – Pockets of bacteria in infections of the gums and teeth can actually eat through the bone between your mouth and your maxillary sinuses. The bacteria then spread up to the sinus, causing an infection. This is most often caused by severe infections, particularly in the back teeth of your upper jaw.

Fungi tend to be much rarer but can still pose as a potential initiator of sinus infections. They are most common in people with immunodeficient disorders or otherwise compromised immune systems. Sinus infections caused by fungi are also common in victims caught in hurricanes, tsunamis, earthquakes, and other natural disasters that may cause a dispersal of fungi from the soil and water.

When you breathe in a fungus, it can grow within your sinuses, blocking airways and potentially cutting off blood supply to essential tissue in the nose and eyes. Aspergillus is one of the most common fungi associated with sinus infection.

Common Symptoms of a Sinus Infection

While sinusitis symptoms can differ from person to person based on the severity of the infection, most people will experience the same general suite of symptoms. These include:

  • Aches and pains – The most obvious and common symptom, aches and pains in any of the sinuses are caused by inflammation and swelling, which create a dull pressure that seems to push against your face. This includes pain in the forehead, between your eyes, in your teeth and upper jaw, and on both sides of your nose. This also causes visible swelling around the face and facial tenderness.
  • Headaches – The excess pressure, blocked air passages, and swelling associated with sinus infections can lead to headaches. These are usually at their most severe in the morning as the fluids have built up inside your sinuses all night long. Your headache can then get worse with sudden dramatic changes in weather. Due to added pressure around the nerves and tissue surrounding the sinuses, you may also suffer form toothaches, earaches, and general pain in your cheeks and jaws.
  • Fever – Common to any infection, a higher body temperature is one of your body’s natural defense mechanisms against invading bacteria, viruses, and other foreign bodies.
  • Sinus discharge – Sinus infections often result in a greenish-yellow discharge leaking out your nose, forcing you to blow your nose more often. In some sinus infections, the discharge may bypass your nose entirely and be rerouted to the back of your throat. This may cause an itch or tickle in your throat and is known as a postnasal drip. During the day, you may find yourself clearing your throat more often, but at night and immediately after you wake up, you may find yourself coughing more. Postnasal drips can also make your voice sound hoarser.
  • Congestion – With a sinus infection, you may find yourself breathing out of your mouth more often. Blockage and inflammation in your sinuses can keep you from breathing properly out of your nose, which can also result in your not being able to smell or taste normally. You may also sound more stuffed up when you talk.
  • Cough – As the discharge builds up, it will work its way down the back of your throat, which leads to irritation. Over a long period of time, this irritation can get worse, leading to persistent coughing, which only gets worse when you lie down to sleep. You may want to prop yourself up when you sleep to prevent the coughing.
  • Sore throat – The irritation caused by postnasal drip will also present itself in the form of a sore throat. While it can start as a mere tickling sensation, your sore throat can get worse as the mucus further irritates and inflames the lining, leading to greater soreness and a scratchy voice.
  • Ulceration – Ulceration is possible in sinus infections caused by a fungus. These ulcers appear around the nasal area with a dark necrotic center and sharply defined edges.

Types of Sinus Infections

Sinus infections can be categorized based on their duration and severity.

  • Acute sinusitis – Acute sinus infections generally come after viral or bacterial infections of the upper respiratory tract (common cold), though they can also be triggered by allergens and pollutants. Acute sinus infections tend to be the most common, and as bothersome as they may be, they generally should not last more than 30 days.
  • Sub-acute sinusitis – Sub-acute sinus infections pose many of the same symptoms as acute sinusitis but tend to last longer—over a month but less than 3 months.
  • Recurrent acute sinusitis – You may be diagnosed with recurrent acute sinusitis if you experience two to four episodes of sinus infections in one year with about 8 weeks between each episode. Between episodes, the lining in your sinuses should normalize.

Sinus infections can also be categorized as infectious or noninfectious. Cases of infectious sinusitis are caused by uncomplicated viral infections and bacterial growth. Noninfectious sinusitis is caused by allergic conditions, irritants, and pollutants in the environment.

A Look at Chronic Sinus Infections

Chronis sinus infections can pose a whole new set of issues on their own. Sinus infections are diagnosed as chronic when they last longer than 3 months. Chronic sinusitis is one of the most prevalent chronic illnesses in the nation, affecting about 146 people per population of 1,000.

In most cases, chronic sinus infections are a continuation of unresolved acute sinus infections, but they may also be caused by fungi. They are also common in people who have compromised immune systems from preexisting conditions, such as diabetes, AIDS, and leukemia.

As chronic sinus infections are usually accompanied by symptoms of nasal inflammation, chronic sinusitis is often called chronic rhinosinusitis (or CRS). Chronic rhinosinusitis can be classified further as:

  • Chronic rhinosinusitis with nasal polyps
  • Chronic rhinosinusitis without nasal polyps
  • Allergic fungal rhinosinusitis

Chronic sinus infections can also be linked to allergens, cystic fibrosis, environmental pollutants, and gastroesophageal reflux. Chronic sinusitis may also point to anatomical abnormalities, such as a deviated septum or obstruction in the ostiomeatal complex.

When to Contact a Doctor

If you exhibit any symptoms of sinus infection for several weeks, make an appointment with your doctor as soon as possible. You should also contact your doctor if you experience any pressure or pain in your upper face, accompanied with postnasal drip, nasal discharge, bad breath that isn’t related to dental issues, or a high fever that lasts several days.

If left untreated, your sinus infection can pose more serious health issues, including:

  • Changes to vision and potential blindness
  • Changes to personality
  • Seizures
  • Meningitis
  • Osteomyelitis, or Pott’s puffy tumor, a condition indicating an infection of the frontal bone in the forehead (this is mainly limited to children)

Sinus infections, particularly those caused by viruses, will generally clear up on their own. Treatments for other sinus infections are available and mainly center around a course of antibiotics. However, even if you have a simple acute sinus infection, you should consider consulting your doctor or visit an urgent care center for relief from any uncomfortable symptoms.

Read more of our Sinus Infection Series:

Sinus Infection vs. Cold: What's the Difference?

Can A Sinus Infection Go Away Without Antibiotics

Can A Sinus Infection Cause Tooth Pain?

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Alexa Englehart

Alexa Englehart

Alexa currently lives in sunny San Diego, California. When not writing, she enjoys running, hiking, swimming, horseback riding, and reading.

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