Facial pressure, postnasal drip, and congestion are common signs of sinus inflammation, also known as sinusitis. When symptoms persist for up to 12 weeks, sinusitis shifts from being acute to what’s known as subacute sinusitis.

Sinusitis is inflammation of the paranasal sinuses. Your sinuses are the air-filled pockets in the bones around your eyes and nose.

Subacute sinusitis is one of four types of sinusitis. These inflammatory conditions can last for days or weeks at a time. Healthcare professionals diagnose sinusitis based on your symptoms and how long you’ve been experiencing them.

Classifying sinusitis by duration lets your doctor set expectations for home treatment, medication use, and more advanced medical procedures or tests.

If you’ve been diagnosed with subacute sinusitis, your symptoms have lasted longer than acute sinusitis but not so long they’re considered chronic sinusitis.

Sinusitis symptoms are the same, regardless of type. They typically develop after a cold or as a result of persistent or severe allergy symptoms.

Signs you might have sinusitis include:

Sinusitis symptoms can vary depending on their underlying cause. Some people may develop a fever, for example, when sinusitis is related to infection.

Sometimes, variations in your symptoms can provide diagnostic clues for your doctor.

The mucus in your runny nose, for example, can come in a variety of colors. Green discharge could signify an infection, while white discharge might be related to allergies. Brown or pink mucus could indicate bleeding in the sinus tissues.

Sinusitis covers a broad range of conditions that cause sinus inflammation.

Some of these, like allergies, may only cause mild inflammation that lasts a few days or a week. You may be able to manage it at home with self-care.

Sinusitis symptoms that don’t improve or worsen can be a sign of more complicated inflammatory processes, like those linked to severe bacterial infections, nasal polyps, or a weakened immune system.

These conditions typically require medical attention.

Like other forms of sinusitis, subacute sinusitis develops when the mucous membranes in your sinus cavities become inflamed, irritated, and swollen.

In addition to the causes outlined above, sinusitis can result from:

  • fungi
  • smoke
  • animal dander
  • dust
  • pollution
  • deviated septum or other structural changes in the nose
  • chronic health conditions that promote mucus buildup

The main diagnostic factor for subacute sinusitis is how long you’ve been experiencing your symptoms:

  • Acute sinusitis: Symptoms last for fewer than 4 weeks.
  • Subacute sinusitis: Symptoms last longer than 4 weeks but fewer than 12 weeks.
  • Chronic sinusitis: Symptoms last more than 12 weeks.
  • Recurrent sinusitis: There are at least four episodes of acute sinusitis within a 12-month period.

But first, your healthcare professional needs to evaluate you for sinusitis.

During the exam, they’ll ask questions about what you’re experiencing. They may want to know when your symptoms started, whether they’ve changed or progressed, and whether this is a recurring experience for you.

Once they’ve heard the full history, a physical exam helps them assess sinus inflammation and rule out other possible diagnoses.

Using their fingertips, your doctor may apply gentle pressure along your face to look for pain, swelling, or tenderness. They may also use a handheld, lighted viewing tool (otoscope) to check the structures of your eyes, nose, ears, and mouth.

Your clinician may recommend additional tests to ensure nothing goes unnoticed.

Diagnostic imaging, like radiographs and CT scans, can reveal structural concerns or unexpected masses in the sinuses.

Laboratory tests, like blood work, can screen for allergies or underlying diseases that may contribute to sinusitis.

Your doctor may also recommend a nasal endoscopy, a procedure that uses a rigid telescope to view the interior of your nasal cavities.

The results of your physical exam and diagnostic tests will lay the foundation for how your sinusitis gets treated.

Most cases of acute sinusitis are self-limiting, which means they resolve independently without needing medical intervention.

Subacute sinusitis may respond to home treatments such as:

The Centers for Disease Control and Prevention (CDC) recommends consulting with a healthcare professional anytime sinusitis lasts more than 10 days without improvement. Your clinician may recommend a 1–2 week course of antibiotics.

If your symptoms remain unchanged or worsen after antibiotics, they may refer you to an ear, nose, and throat (ENT) specialist.

Sinusitis is inflammation in your paranasal sinus cavities. Several types of sinusitis exist, defined by the duration of their symptoms.

Acute sinusitis lasts fewer than 4 weeks, while subacute sinusitis lasts more than 4 weeks but fewer than 12. Chronic sinusitis persists for 12 weeks or longer.

Subacute sinusitis is treatable and typically resolves with the use of home treatments or prescription antibiotics.

In some cases, your clinician may recommend diagnostic imaging or laboratory testing to rule out conditions related to chronic sinusitis.