Viral Sinusitis (Sinus Infection)

What is sinusitis (sinus infection)?

Sinusitis, also referred to as sinus infection or rhinosinusitis, is inflammation of the sinuses. The sinuses are air-filled cavities within the bones in the face and nose; sinusitis occurs when these cavities become inflamed and blocked, leading to a buildup of mucus and air. It is a common condition, occurring in many cases following a cold.[1]

Symptoms of sinusitis include nasal discharge, a blocked nose, tenderness around the head and sinus headaches. Generally, sinusitis is a non-serious condition which can be managed through self-care methods and over-the-counter medication. In most cases, symptoms will disappear within two to three weeks.

Types of sinusitis

There are two types of sinusitis:[2]

  • Acute sinusitis is defined as an infection that develops suddenly and lasts for a short amount of time. This will typically be around a week, though a duration of two to three weeks is not uncommon. Individuals experiencing a cold will often also develop a mild case of acute sinusitis, with most people only experiencing severe acute sinusitis once or twice in their lifetime.
  • Chronic sinusitis is far less common than acute sinusitis. It is defined as persistent sinusitis that lasts for over 12 weeks. In most cases, chronic sinusitis will develop from acute sinusitis.

Symptoms of sinusitis (sinus infection)

Sinusitis often develops following a cold. If the following symptoms are experienced at the same time as the various symptoms of a cold, it may indicate that sinusitis has developed:[3][4]

  • Yellow or green nasal discharge
  • A blocked or runny nose
  • Pain and tenderness around the affected sinuses (commonly less severe in chronic sinusitis)
  • Sinus pressure
  • Fever (above 38 C / 100.4 F)
  • Toothache
  • A reduced sense of smell (most common in chronic sinusitis)
  • Bad breath

In cases of chronic sinusitis, the severity of symptoms may vary over time. During an initial bout of acute sinusitis, symptoms may be severe, but fade over a number of days or weeks, leaving background symptoms such as mild sinus discomfort and stuffiness. Acute sinusitis may then redevelop, making symptoms once again severe.

When to see a doctor

Most mild cases of sinusitis will not require a visit to the doctor. However, if the following symptoms occur, medical attention is advised:

  • Symptoms are severe
  • Symptoms are getting worse
  • Frequent bouts of sinusitis are experienced

Causes of sinusitis (sinus infection)

The causes of acute and chronic sinusitis are typically different.

Causes of acute sinusitis

In the majority of cases, acute sinusitis is caused by a viral infection. This will typically be the same virus as has caused the preceding cold. The condition may also be caused by bacteria. This, however, is rare, only occurring in roughly 0.5 to 2 percent of cases.[5]

Causes of chronic sinusitis

The causes of chronic sinusitis are more multifaceted than the acute form of the condition. Although a viral infection may play a role in causing chronic sinusitis, long-term inflammation will often also have other contributing factors.[6]

Medical experts have identified three general categories of chronic sinusitis, each with different causes:

  • Chronic sinusitis without nasal polyposis: The most common form; typically caused by allergic reactions to airborne substances, irritation from airborne substances and infections.
  • Chronic sinusitis with nasal polyposis: Nasal polyps are abnormal growths within the nose. When polyps become large or numerous, they can block the airways and cause sinusitis. The reasons why some people develop nasal polyps are largely unknown.
  • Chronic sinusitis with fungal allergy: Air routinely contains small amounts of fungus, which most people can inhale without issue. Others, however, can experience an allergic reaction to this fungus, which causes a thick mucus to form in the sinuses. This can then lead to chronic sinusitis.

Several factors can make an individual more prone to chronic sinusitis or make the symptoms worse when the condition is being experienced. These include:

  • Allergies, especially those that are experienced all year round, can both increase one’s risk of chronic sinusitis and worsen its symptoms. These allergies include those to dust mites, animal hair and mold.
  • Airborne irritants, including things like tobacco smoke and formaldehyde, can increase the risk of developing chronic sinusitis.
  • People with an immune system disorder are at increased risk of developing chronic sinusitis.

Diagnosing sinusitis (sinus infection)

Most cases of sinusitis will resolve themselves in around one to three weeks and not require a visit to the doctor. However, if a person is concerned about their symptoms, they are particularly severe or last longer than the normal timeframe, seeking medical attention is advised.

Upon visiting a doctor, they will typically ask some questions about the symptoms being experienced and perform a physical examination. This may include an anterior rhinoscopy, which involves a doctor using a lighted instrument to examine the nose and sinuses. Through this, a doctor will usually be able to confirm a diagnosis of sinusitis. If the symptoms persist for longer than 12 weeks, a doctor will be able to confirm a diagnosis of chronic sinusitis.

If chronic sinusitis is confirmed, further tests may be required to establish what form of the condition is being experienced. This may involve a nasal endoscopy, in which a lighted, flexible tube mounted with a camera is inserted into the nasal cavity and sinuses for examination purposes.[7]

Sinusitis (sinus infection) treatment

Acute sinusitis and chronic sinusitis will typically require different treatment methods.

Treatment for acute sinusitis

In most cases, acute sinusitis will not require any specialist treatment from a doctor. As the condition will typically resolve itself naturally in a number of weeks, a combination of self-care methods and over-the-counter medications is usually sufficient. This includes:[8][9]

  • Painkillers such as ibuprofen and paracetamol can help with pain relief.
  • Decongestant nasal sprays can be effective in the short-term at resolving a blocked nose. However, long-term use (over 5-7 days) is not advised.
  • Staying hydrated and getting plenty of rest is advised to aid recovery.
  • Warm face packs or a warm flannel placed over the face can help ease congestion and a blocked nose.

If the symptoms are particularly severe, a doctor may prescribe:

  • Antibiotics may be prescribed in rare cases. As acute sinusitis is typically caused by a virus, antibiotics cannot be used as a cure. However, they may be prescribed when symptoms are severe; when an individual also has a heart problem, cystic fibrosis or a weak immune system; or when symptoms do not seem to be getting better or are worsening.
  • Steroidal nasal sprays may be prescribed to help relieve particularly severe sinus inflammation.

Treatment for chronic sinusitis

Chronic sinusitis will generally require long-term management. Different people will require different treatment methods, depending on which type of the condition is being experienced, its severity and whether any other conditions are also being experienced.

Treatment methods include:[10]

  • Lifestyle changes: People with chronic sinusitis who smoke cigarettes should quit, as smoke can aggravate the condition. Moreover, people with allergies which contribute to their condition should aim to limit their exposure to allergens. This may involve making environmental changes at home or in the workplace.
  • Saline solution: Daily washing of the nasal passageways with a saline solution may be useful in helping to reduce inflammation.
  • Steroid nasal sprays: Nasal sprays containing steroids are effective at reducing inflammation. Doctors will normally prescribe a course, with its length depending on the severity of the condition. If inflammation is very severe, steroid pills may be prescribed. However, this is not routine due to the risk of side-effects such as sleeping problems and acne.
  • Antibiotics: In some cases, sinusitis may result from a bacterial infection. In these cases, antibiotics may be prescribed. The course will generally need to be prolonged (3-4 weeks).
  • Over-the-counter medications: If the symptoms of acute sinusitis develop on top of the symptoms of chronic sinusitis, painkillers such as ibuprofen and paracetamol can be effective at reducing pain. Decongestant nasal sprays can also be effective at relieving a blocked nose. These nasal sprays, however, provide only short-term relief and should not be used for over 5-7 days at a time.


Taking care to prevent the spread of colds or the flu in the home and community can help prevent some cases of viral sinusitis.

  1. Bupa. “Sinusitis.” Accessed December 8, 2017.

  2. Patient. “Acute Sinusitis.” November 26, 2015. Accessed December 8, 2017.

  3. NHS Choices. “Sinusitis.” May 13, 2015. Accessed December 8, 2017.

  4. Patient. “Chronic Sinusitis.” November 26, 2015. Accessed December 8, 2017.

  5. UpToDate. “Patient education: Acute sinusitis (sinus infection).” October 4, 2017. Accessed December 8, 2017.

  6. UpToDate. “Patient education: Chronic sinusitis (sinus infection).” June 13, 2016. Accessed December 8, 2017.

  7. Bupa. “Sinusitis.” Accessed December 8, 2017.

  8. Patient. “Acute Sinusitis.” November 26, 2015. Accessed December 8, 2017.

  9. Bupa. “Sinusitis.” Accessed December 8, 2017.