How to Tell If You Have a Sinus Infection

February 23, 2026

A man holds the bridge of his nose while sitting back

Stuffy nose, facial tenderness and headache are symptoms that people commonly experience during cold and allergy season. They can also be signs of a sinus infection, says Sanjeet Rangarajan, MD, a rhinologist at University Hospitals. “Most sinus infections start with a viral upper respiratory infection, essentially a cold,” he says.

What Is a Sinus Infection?

Your sinuses are made up of four hollow spaces that are situated in and around your forehead and nose on the inside of your head. The lining of your sinuses (called mucosa) can become inflamed for many reasons, says Dr. Rangarajan.

Sinus inflammation can be caused by:

Allergies
Colds
Environmental exposures (smoke, pollen, dust, mold, chemicals, air pollution)
Infections
Reactive upper respiratory diseases (chronic coughing, wheezing, difficulty breathing)

“When inflammation in the sinuses is caused by a viral, bacterial or fungal infection, it’s considered a sinus infection or sinusitis,” says Dr. Rangarajan.

Symptoms

Sinus infections can cause a range of symptoms – from a stuffy nose to facial pressure. Signs of infection can vary from person to person, but Dr. Rangarajan says the classic symptoms of a sinus infection are:

Congestion
Facial pressure or pain
Thick nasal drainage
A reduced or absent sense of smell

Additional symptoms may include:

Post-nasal drainage
Cough
Ear fullness
Fatigue
Headache
Light fever
Pain in the teeth
Runny nose
Sore throat

“One important misconception is that discolored mucus – yellow, brown or green – means infection,” says Dr. Rangarajan. “On its own, it usually reflects inflammation, not bacteria.”

Causes

Sinus infections usually start when something inflames the sinuses and prevents them from draining normally. There are many things that can irritate and inflame your sinuses, but sinus infections typically have three possible causes: viral, bacterial or fungal.

Most sinus infections are viral. Less than 2% are caused by bacteria. “That distinction matters, because most sinus symptoms don’t require antibiotics,” says Dr. Rangarajan. When you get a cold, the virus causes swelling in the nasal passages and sinuses, which blocks drainage and creates pressure, along with mucus buildup, where germs and bacteria can grow.

Some people are more likely than others to develop sinus infections or get recurring infections. “Many patients who report frequent ‘sinus infections’ are actually dealing with chronic sinus inflammation rather than repeated bacterial infections,” says Dr. Rangarajan. “Identifying and treating those underlying factors is key.”

Underlying factors that can increase your risk of sinus infection include:

Allergies
Asthma
Smoking
Immune system issues
Dental disease
Rheumatologic issues
Deviated septum
Nasal polyps

Diagnosis

Sinus infections are typically diagnosed based on your symptoms and how long you’ve had them. “Imaging isn’t needed for routine cases, and studies like sinus plain film x-rays are often unhelpful,” says Dr. Rangarajan. A nasal endoscopy (a thin tube with a light and camera are used to examine the nasal passage and sinuses) or CT scan may be recommended if your symptoms don’t go away or they keep coming back, he says. These tests can help detect if there are any abnormalities or blockages in your sinuses and whether chronic sinus disease is present.

Dr. Rangarajan advises seeking care if your symptoms:

Last longer than 10 days without improvement.
Worsen after initially improving.
Are unusually severe.

“Serious complications are rare but can occur, and can spread to the eyes or brain,” he says. “Warning signs like eye swelling, vision changes, severe headache or high fever need prompt medical evaluation.”

How to Treat and Prevent Sinus Infections

Most sinus infections are treated with saline nasal irrigation, intranasal steroid sprays and supportive care, says Dr. Rangarajan. Antibiotics are only helpful when severe early symptoms, prolonged symptoms or “double worsening” symptoms (symptoms that seem like they’re getting better get worse again) strongly indicate that it’s a bacterial infection.

“Because the underlying cause is usually viral and inflammatory, treatment focuses on reducing inflammation and improving drainage,” says Dr. Rangarajan. “Decongestants, nasal sprays and saline nasal irrigations can be very helpful, along with rest, good nutrition and all the other healthy habits for someone who is ill.”

Dr. Rangarajan points out that some people have anatomic issues (like a deviated septum) that can lead to sinus infections or chronic sinusitis. These can be managed with a medical regimen tailored to the patient’s symptoms and anatomy. “For some, an endoscopic sinus surgery may be recommended,” he says. This is a minimally invasive procedure that can help reduce or eliminate sinus symptoms.

How Sinus Care Is Evolving

“Sinus care today looks very different than even 20 years ago,” says Dr. Rangarajan. Recent advances in sinus care have resulted in more options for managing symptoms. “Modern treatment focuses on restoring healthy sinus function and controlling the underlying cause of inflammation rather than repeatedly treating presumed infections or aggressive surgery,” he says. Antibiotics are no longer a first-line treatment for most sinus infections.

The medical community also has a better understanding of how sinus infections develop, which has led to more effective options for treating them. Some of the newer treatments are particularly successful at helping people with frequent or persistent sinus infections, says Dr. Rangarajan. These include high-volume topical steroid therapies, office-based procedures for selected patients, new endoscopic sinus surgery techniques and biologic medications for severe chronic sinusitis with nasal polyps.