The sinuses are hollow cavities in the skull beside or above the nose. Their role is to produce mucus, which moisturizes your nasal passages. Sinusitis is when one or more of the sinuses gets inflamed, which is swelling of the sinus lining and more mucus production. Another term for sinusitis is sinus infection, because infection is a common cause of inflammation. Doctors often classify sinusitis as acute or chronic, depending on how long it has been present. Although anyone can get sinusitis, some people are more prone to developing it. Having asthma or allergies increases your risk of developing chronic sinusitis, as does having a blockage (such as polyps) in your nasal passages. If you suspect you have sinusitis, see your doctor for a diagnosis. You may need antibiotics or other treatments to treat the infection, and maybe to relieve the symptoms. The Difference Between Acute Sinusitis and Chronic Sinusitis Sinusitis is subdivided into four categories: Acute Chronic Subacute Recurrent These designations describe how long or often you’ve had sinusitis. All four can cause the same type and intensity of pain or discomfort, but they may have different causes and require different treatment approaches. Acute sinusitis is typically an infection in a sinus cavity that lasts no longer than 30 days. Viruses cause most sinus infections, but bacteria and fungi can also cause it. Sinusitis symptoms lasting longer than 90 days is chronic sinusitis. However, if your sinusitis falls between acute and chronic, meaning it lasts longer than 30 days but not past 90 days, it is subacute sinusitis. Some people get frequent or repeat acute sinus infections. They clear up, either on their own or with treatment, but another infection develops. Four or more bouts of acute sinusitis in one year is recurrent sinusitis. Acute or Chronic Sinusitis: Symptoms Are Similar The symptoms of sinusitis are similar regardless of the subgroup—acute, chronic, subacute or recurrent. The most common symptoms are: Pressure or pain in your face, around your cheekbones, around your upper teeth, or up to your forehead Pain or pressure in your face or headache that worsens when you bend down Tenderness over specific sinuses when you touch your face Swelling over specific sinuses Nasal congestion, stuffiness Green or yellow discharge from your nose Dripping sensation down the back of your throat Foul taste in your mouth Bad breath Cough, particularly when you are lying down Fever Differing Causes Between Acute and Chronic Sinusitis While viruses, bacteria and even fungi can cause acute sinusitis, acute infections most often follow a viral illness, such as a cold or the flu. Chronic sinusitis, on the other hand, is persistent inflammation, often complicated by infections, allergies, malformations or blockages in the nasal passages, trauma to the nose or sinuses, or breathing in irritants, such as smoke or pollution. Keep in mind, chronic sinusitis is not simply an acute sinus infection that hasn’t cleared up. In fact, it doesn’t necessarily have to be an infection at all. Diagnosing Acute and Chronic Sinusitis Acute sinusitis is usually diagnosed based on your symptoms, although your doctor may request a CT (computed tomography) scan or X-ray to verify the diagnosis in some cases. If you have chronic sinusitis or recurrent sinusitis, a CT will help your doctor see the extent of the infection or inflammation, and how many of the sinuses are affected. An ear, nose and throat specialist (ENT, otorhinolaryngologist or otolaryngologist) may perform a nasal endoscopy. After applying a local anesthetic, the doctor inserts an endoscope (a long narrow tube with a camera on the end) into your nose to see the inside of your nasal passages. Your doctor may also take a swab of the discharge to check for bacteria or fungi. Allergy tests may reveal if certain allergens could be contributing to chronic sinusitis. Although both acute and chronic sinusitis can cause significant pain and discomfort, the causes are different and treatment must target the causes. To avoid complications of sinusitis, it’s important to see your doctor or nurse practitioner for an accurate diagnosis and treatment plan if you are experiencing symptoms of sinusitis.