A sinus infection, also known as sinusitis, occurs when the lining of the sinuses becomes inflamed, causing swelling and a build-up of mucus. The condition often develops after a cold or flu and can cause nasal congestion, facial pain, headaches and a reduced sense of smell.
Most sinus infections are caused by viruses and improve without antibiotics. Bacterial infections account for a smaller proportion of cases, and symptoms alone do not always establish which type of infection is present, according to the US Centers for Disease Control and Prevention (CDC).
Common symptoms of a sinus infection
Symptoms vary depending on the cause and severity of the inflammation. They may include:
- Nasal congestion or a blocked nose.
- A runny nose or mucus draining down the throat.
- Pain, pressure or tenderness around the cheeks, eyes or forehead.
- Headaches.
- Reduced or lost sense of smell.
- Sneezing.
- Sore throat.
- Cough.
- Fever.
- Fatigue.
- Bad breath.
- Toothache.
- A feeling of pressure in the ears.
Some people also experience irritability, particularly children who have difficulty sleeping or breathing comfortably through the nose.
Itchy or watery eyes and frequent sneezing may occur alongside nasal symptoms, but they can also indicate allergic rhinitis, a condition in which the immune system reacts to substances such as pollen, dust or animal dander.
Nausea, heartburn, gastrointestinal pain, chest pain and a fast heartbeat are not among the main symptoms used to identify sinusitis. These symptoms may have other causes and should not automatically be attributed to a sinus infection.
Headaches and facial pressure
Headaches associated with sinusitis may occur alongside facial pain, nasal blockage and pressure around the forehead, cheeks or eyes. The discomfort can become more noticeable when the sinuses are inflamed and mucus drainage is restricted.
However, not every headache accompanied by nasal congestion is caused by sinusitis. Migraine and other headache disorders can produce symptoms that resemble a sinus headache.
Rest, adequate fluid intake and a warm compress placed over the nose and forehead may help relieve discomfort. Pain-relief medicines may also help when used according to their labels and with advice from a healthcare professional or pharmacist.
Severe or unusual headaches, particularly those accompanied by vision changes, confusion or swelling around the eyes, require urgent medical assessment.
Nasal congestion and discoloured mucus
Inflammation causes the lining of the nose and sinuses to swell, making it harder for mucus to drain. This can lead to a blocked nose, a runny nose and a sensation of pressure in the face.
Mucus may appear clear, white, yellow or green. However, its colour alone cannot determine whether an infection is bacterial or whether antibiotics are needed.
Sinusitis may also cause mucus to drain down the back of the throat, leading to coughing, throat irritation or bad breath.
A cold and sinusitis can share many symptoms. A cold may trigger sinus inflammation, so the two conditions are not necessarily separate illnesses.
How long does sinusitis last?
Acute sinusitis commonly improves within two to three weeks, although some cases take longer. The duration depends on the cause and severity of the illness.
The CDC advises seeking medical attention when symptoms last more than 10 days without improvement, become severe, worsen after initially improving, or are accompanied by a fever lasting more than three to four days.
These patterns may indicate a bacterial infection or another condition that needs further assessment. People with weakened immune systems should also seek medical advice when symptoms develop or persist.
How sinus infections are treated
Treatment depends on the cause of the infection and the severity of symptoms.
For many cases, care focuses on relieving symptoms while the body recovers. Options include saline nasal sprays, warm compresses and suitable pain-relief medicines. A healthcare professional or pharmacist can advise on other treatments, including nasal corticosteroids or antihistamines when appropriate.
Antibiotics are not routinely needed for sinus infections. They treat bacterial infections, not viral illnesses, and unnecessary use can cause side effects and contribute to antibiotic resistance.
A healthcare professional may prescribe antibiotics when a bacterial infection is suspected and treatment is appropriate. The choice of medicine and length of treatment depend on the individual case. Patients should take prescribed antibiotics exactly as directed and should not use leftover medicines or antibiotics prescribed for someone else.
Azithromycin, sold under brand names including Zithromax, is not a routine first-choice treatment for bacterial sinusitis under CDC guidance because of resistance among some bacteria that commonly cause respiratory infections.
When to seek medical attention
Most sinus infections resolve without serious complications, but some symptoms require prompt assessment.
Seek medical advice if symptoms persist for more than 10 days without improvement, worsen after initially getting better, or are accompanied by a prolonged fever or significant facial pain.
Seek urgent medical care for swelling or redness around the eyes, double vision, reduced vision, a severe frontal headache, confusion or other signs of a potentially serious complication.
People with chest pain, a persistently fast heartbeat or difficulty breathing should also receive prompt medical assessment rather than assuming these symptoms are caused by sinusitis.
Early assessment can help identify the cause of the symptoms and determine whether self-care, medication or further investigation is needed.
