The four main types of sinusitis are acute, subacute, chronic, and recurrent (these are based on how long a person's symptoms have been present). Within these categories, there may be more specific types. For example, chronic sinusitis may be broken down into different categories based on whether a person has nasal polyps or allergic fungal chronic rhinosinusitis.
What Are the Different Types of Sinusitis?Sinusitis occurs when the sinuses become swollen, irritated, and inflamed. Based on how long symptoms have been present, healthcare providers will classify it as one of four types. These types include:
- Acute sinusitis (symptoms lasting for fewer than 4 weeks)
- Subacute sinusitis (symptoms lasting between 4 and 12 weeks)
- Chronic sinusitis (symptoms lasting 12 weeks or longer)
- Recurrent sinusitis.
Healthcare providers often will use the term "rhinosinusitis" instead of just "sinusitis." This is because inflammation of the sinuses rarely happens without inflammation also happening inside the nose. The medical term for the nasal passages is "rhino."
The term "sinusitis" may also be used interchangeably with "sinus infection," although technically not all cases of sinusitis are caused by an infection.
Types of Acute Sinus InfectionsAcute sinusitis is diagnosed when symptoms have been present for fewer than four weeks. This condition can also be separated into different types. These include acute viral rhinosinusitis (AVRS) and acute bacterial rhinosinusitis (ABRS). AVRS is by far the most common type. It is responsible for up to 98 percent of all acute sinusitis cases.
- Chronic rhinosinusitis without nasal polyposis (polyps)
- Chronic rhinosinusitis with nasal polyps
- Allergic fungal chronic rhinosinusitis.
About one in three people is diagnosed with chronic rhinosinusitis with nasal polyps. Nasal polyps are clear masses filled with gelatin-like inflammatory material that can be yellow-grey to white in color. They may occur in the nasal passages or paranasal sinuses. In order to make this diagnosis, the polyps must be present on both sides.
Chronic rhinosinusitis with nasal polyposis usually affects people with a normal immune system. These people may be sensitive to aspirin and nonsteroidal anti-inflammatory drugs (NSAIDs).
About 1 in 10 people is diagnosed with allergic fungal chronic rhinosinusitis. This type of chronic sinusitis is different from fungal sinusitis. People with allergic fungal chronic rhinosinusitis may or may not have polyps. But they do have:
- An allergy to certain types of fungus.
- "Allergic mucus." Allergic mucus within the nose or sinuses has fungi inside of it and certain other chemicals that show an allergic reaction to these fungi.
Fungal chronic rhinosinusitis also affects people with a normal immune system.
Chronic rhinosinusitis without nasal polyposis is the most common form of chronic sinusitis. About two in every three people have this type. It is diagnosed if a person does not meet the criteria for the other two types of chronic sinusitis.
People at risk for this form of chronic sinusitis include those with:
- Allergies (allergic rhinitis, hay fever, seasonal allergies, year-round allergies)
- Non-allergic rhinitis
- A weakened immune system, such as in people with HIV, AIDS, or diabetes, along with people who have low blood counts because of chemotherapy or who have had an organ transplant.