Sinus infection, also referred to as sinusitis or rhinosinusitis, is an inflammation of the tissue lining the sinus cavities.
The inflammation, caused by a virus, bacteria, fungus or as a result of allergies, prevents the sinuses - a connected system of air-filled cavities located in the skull - from draining normally, leading to a build-up of mucus and secondary infection.
Acute sinusitis often occurs after a viral upper respiratory tract infection (URI).
The main symptoms of sinus infection are nasal obstruction, discolored nasal discharge, and facial pain or pressure that has been present for 7 days or more.
Fast facts on sinusitis
Here are some key points about sinusitis.
- Normally, the sinuses are empty except for a thin layer of mucus
- When the sinuses become inflamed and swollen, they are no longer able to drain mucus, resulting in a build-up
- Sinusitis can be acute (lasting less than 4 weeks), sub-acute (lasting no more than 12 weeks) or chronic (lasting 12 weeks or more)
- The overwhelming majority of cases of sinusitis are viral in nature and require symptomatic relief, not antibiotics
- Only about 0.5-2.0% of sinus infections episodes are bacterial
- Antibiotics are the primary form of medical treatment for acute bacterial sinusitis
- Yellow or green sputum color does not prove a sinus infection is bacterial, but rather indicates the presence of white blood cells
- Sinusitis affects an estimated 35 million people per year in the US and accounts for close to 16 million office visits per year.
Symptoms of sinus infection
A sinus infection consists of three main symptoms:
Facial pain or pressure is one of the three main symptoms of sinusitis.
- Facial pain or pressure
- Nasal obstruction
- Nasal discharge.
The pain from sinusitis may be felt around the eyes, under the eyes, on the forehead and around the nose. Because the roots of the teeth project into the floor of the maxillary sinus, pain is sometimes felt in the teeth.
Sinus pain can also feel like a generalized headache. The pain is often described as throbbing, and may worsen with straining or bending down.
Nasal obstruction and nasal discharge are prominent in sinusitis as the mucosa of the nose and sinuses are adjoining. The drainage may be cloudy or colored green or yellow, blood-tinged, thick and foul-smelling.
Additional symptoms of sinus infection may include:
- Post-nasal drip
- Loss of smell
- A feeling of fullness or pressure in the ear
- Bad breath
When the infection is caused by a virus, the symptoms of sinusitis are cold-like with runny nose, sore throat, sneezing, nasal congestion and coughing. Mucus may be clear, or slightly colored.
Antibiotics are not effective against a viral infection. Management is to treat the symptoms with supportive measures such as rest, fluids, saline nasal sprays and over-the-counter pain relievers and oral decongestants. Sinusitis caused by a virus typically resolves in 7-10 days.
Nasal discharge is one of the three main symptoms of sinusitis.
With a bacterial sinus infection, nasal discharge is thick, green or yellow. The nasal passages are swollen and mucus may be dripping down the back of the throat (post-nasal drip).
This type of sinus infection requires an evaluation by a health care provider for prescription antibiotics such as amoxicillin. The majority of individuals with acute bacterial sinusitis respond successfully to antibiotics, with complete resolution of symptoms in 10-14 days.
When sinusitis is due to allergies, inflammation leads to nasal congestion and swelling of the mucous membranes, which can block normal sinus drainage. Allergic sinusitis often leads to chronic sinusitis. Symptoms can be seasonal, or all year round, and are sneezing, itchy nose, throat, or eyes, nasal congestion, postnasal drip and runny (clear mucus) nose.
Treatment includes antihistamines, avoiding allergic triggers and, in some cases, allergy shots (immunotherapy).
Chronic sinusitis can cause more subtle symptoms that persist for months. Nasal congestion and post-nasal drainage are the most common symptoms of chronic sinusitis. A cough that is worse at night or on awakening in the morning is common in chronic sinusitis as well. Also, individuals with nasal polyps often have this type of infection.
Nasal steroid sprays are typically used as a form of treatment. Fungus is a likely cause of chronic sinusitis.
Potential complications of sinus infection
Although most cases of sinus infection are uncomplicated, there are potentially life-threatening complications of acute bacterial sinusitis that can occur. The walls of the sinuses are thin, and the sinuses share common blood and lymph drainage pathways with the eyes and parts of the central nervous system.
Complications of sinus infection include:
- Infection of the eye and its surrounding tissue
- Sinus cavity blood clot (thrombosis)
- Brain abscess
- Bone infection.
Symptoms of these rare complications include:
Fast facts about meningitis
- Meningitis is the inflammation of membranes that envelope the brain and spinal cord
- Around 10-12% of meningitis cases in industrialized countries are fatal.
- Redness or swelling in the eye or eye socket
- Pain with eye movements
- Changes in vision
- Drooping eyelid
- Sensitivity to light
- Swelling of the forehead
- Severe headache
- Onset of fever
- Inability to move neck forward (nuchal rigidity).
Immediate medical attention is required for any symptom that suggests a potential complication of sinusitis.
Sinus infection is one of the most commonly diagnosed diseases in the US, affecting an estimated 16% of the adult population annually.
The three main symptoms of sinusitis are nasal obstruction, nasal discharge and facial pain or pressure. The vast majority of cases of sinusitis are due to a virus and clear on their own in 7-10 days. When symptoms extend beyond 10 days or worsen in severity, evaluation by a health care provider is recommended.
Learn more about sinusitis, including how it is caused and treated.