American College of Physicians: Internal Medicine — Doctors for Adults ®


Special Focus: Acute Sinusitis

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From the January-February ACP Observer, copyright 2007 by the American College of Physicians.

The National Institute of Allergy and Infectious Diseases (NIAID) estimates that 37 million Americans suffer from sinusitis each year, accounting for $5.8 billion a year in related health costs. Sinusitis is the fifth most common reason to visit a primary care physician, according to a 2005 study published in the Journal of Family Practice.

"It is fairly predictable every year that during the winter there will be more in the way of viral illnesses and colds in a variety of different types of patients. Some of these patients develop acute sinusitis," said Kenneth Smith, FACP, assistant professor of medicine at the University of Pittsburgh Medical Center, and editorial consultant for PIER's module on acute sinusitis.

Most cases of sporadic acute sinusitis are due to viral or bacterial infection, while some are caused by trauma or exposure to noxious agents. Atopic disease, which occurs in about 15% of the U.S. population, may predispose patients to sinusitis, as does smoking.

Doctors are familiar with acute sinusitis in their practices, but the condition lacks an evidence-based definition, Dr. Smith continued.

Magnetic resonance image of sinusitis, showing inflammation of the mucous membrane.

"A lot of our decisions in terms of treatment are based on duration rather than whether or not sinusitis is present," Dr. Smith said. "Most people have viral sinusitis, which should clear rather rapidly, whereas [those with] bacterial infections will tend to have symptoms longer or more severely."

Symptom duration and severity are most often used to diagnose acute sinusitis in patients with upper respiratory infections. For example, the risk of sinusitis is considerably higher when the patient's upper respiratory infection has lasted for seven days, or there is facial pain or purulent discharge. "We're dealing with a greater than 50% probability rather than definite diagnostic criteria, and that makes studying an illness that much more difficult when you're dealing with a probability rather than a certainty."

This edition of ACP Observer Special Focus is designed to help optimize your ability to diagnose, treat and manage patients with acute sinusitis.


Many patients who come into the office with a cold that just won't go away think they may have sinusitis, and it is indeed often difficult to differentiate a lingering viral upper respiratory infection (URI) from acute sinusitis. In fact, acute sinusitis is usually a complication of a viral URI. Given the contiguity of the sinuses with the nasopharynx, the term rhinosinusitis is often preferred to characterize inflammation of both.

Patient history can differentiate infectious causes of rhinosinusitis from those due to allergy or environmental irritants, such as smoke or trauma. Although allergic rhinitis can predispose patients to acute infection, other underlying conditions more commonly cause chronic or recurrent sinusitis. Some of these include:

  • Diabetes
  • HIV disease and immunosuppressive medications
  • Anatomic abnormalities of the sinuses and nasal passages
  • Cystic fibrosis

The most important historical symptoms to inquire about are:

  • purulent rhinorrhea (rhinorrhea and facial pain may be unilateral or bilateral),
  • localized facial pain (most often over the maxillary sinuses) and
  • duration of illness beyond seven days.

Although most sinusitis is probably caused by viral infection, a few studies (using imaging criteria or the true gold standard of sinus puncture and bacteriologic analysis) have found that the above three factors correlate best with the diagnosis of bacterial sinusitis. Good evidence is lacking for other symptoms such as fever, facial pain and pressure that worsen on bending over, halitosis, maxillary toothache, and cough.

Duration of illness is important not only as a defining criterion for acute sinusitis but also in management decisions. It is important to distinguish between acute, subacute and chronic sinusitis. Acute sinusitis is defined by duration of disease lasting for less than four weeks, subacute sinusitis is reserved for patients with symptoms lasting from four to 12 weeks and chronic sinusitis is clinically defined by the presence of sinus signs and symptoms for more than 12 weeks. Chronic disease and recurrent episodes unresponsive to treatment suggest the presence of an underlying condition that requires more extensive evaluation.

On physical examination, look for tenderness over the sinuses and pus in the nose and pharynx. In rare cases, spread of infection beyond the sinuses is apparent on examination of the orbital structures or on neurological examination. Again, fever is not a distinguishing factor for acute sinusitis.

Diagnostic Studies

In uncomplicated cases of acute sinusitis, avoid sinus radiography, ultrasonography, CT or MRI. Many imaging modalities have high false positive rates. Asymptomatic patients may demonstrate abnormalities such as mucosal thickening, fluid levels or sinus opacification that do not require treatment. Ultrasonography, although less expensive that plain sinus radiography, is rarely used in the U.S. CT and MRI have no role in the diagnosis of acute sinusitis except when history and physical examination indicate local spread beyond the sinuses or intracranial complications.

At a cost of approximately $100, sinus radiography is not cost-effective or useful compared with symptomatic treatment. The occipitomental (Waters) view is the standard for visualizing the paranasal sinuses, especially the maxillary sinuses; however a series of three or four x-rays is often ordered. Radiographic abnormalities include sinus fluid and opacity. Mucous membrane thickening increases sensitivity but decreases specificity when compared with sinus puncture. Acute viral sinusitis probably causes the same radiographic changes as acute bacterial sinusitis. There have been studies comparing radiography to CT and ultrasonography, but there is no convincing evidence that these two latter modalities offer any clear advantage.

Diagnostic imaging with CT or MRI has no role in the overall management of acute sinusitis but is clearly indicated when clinical examination suggests spread of disease beyond the sinuses or intracranial complications. Advanced imaging techniques and other specialized studies may be required in patients predisposed to unusual bacterial infections, such as those with underlying anatomic abnormalities or immunosuppression. Such patients may be infected with atypical microbial pathogens, such as Pseudomonas aeruginosa or fungi, and a precise bacteriologic diagnosis may be needed to determine optimal therapy, especially when empirical therapy has failed to achieve a satisfactory response. In such cases, sinus puncture and culture of aspirate is the gold standard for diagnosis and should only be performed by a specialist.

Complications and consultations

Most cases of acute viral sinusitis and even most cases of acute bacterial sinusitis are self-limited and respond to supportive therapy. In patients with recurrent episodes of sinusitis, it is often difficult to determine whether it is due to infection with a new organism or a recrudescence of smoldering infection from an incompletely treated pathogen. Patients with chronic disease are often treated with multiple courses of various antibiotics and may harbor resistant organisms. In these patients, chronic sinusitis has a different histopathology and prognosis, requiring advanced imaging and otorhinolaryngologist consultation. When atopic disease is suspected, allergist consultation may also be useful.

The most serious complications are the result of bacterial sinusitis occurring in patients with chronic underlying diseases, such as diabetes, anatomic abnormalities or immunosuppression predisposing them to infection with unusual pathogens. This can lead to local spread of disease causing osteitis of the sinus bones; periorbital and orbital cellulitis; and central nervous system manifestations, such as meningitis, brain abscess or infection of the intracranial venous sinuses, particularly the cavernous sinus. Such complications are usually clinically evident. For example, orbital cellulitis is diagnosed on the basis of orbital swelling, redness of the conjunctiva and limitation of extraocular movements. In such cases, otorhinolaryngologist, neurologist, infectious disease and ophthalmologist consultation are most likely required.


Although there are no well-designed studies to address their effectiveness, it is reasonable to consider sinus irrigation and over-the-counter saline to increase mucosal moisture and remove inflammatory debris and bacteria. Such measures may relieve patients' discomfort, and the cost is low compared with drug therapy.

Then begin to assess the need for further drug therapy by estimating the probability that the patient does or does not have bacterial sinusitis on the basis of the presence or absence of the same factors that led you to initially suspect sinusitis (URI >7 days, facial pain, purulent drainage). The probability of bacterial sinusitis is low if only one of these factors is present and higher if at least two are present.

If the probability of bacterial sinusitis is low, and especially if symptoms are mild or moderate, most patients with rhinosinusitis will improve without antibiotic treatment. Such patients can be treated with symptomatic therapy including an appropriate combination of the following agents:

  • mucolytic agents to reduce viscosity of nasal secretions
  • decongestants to reduce mucosal inflammation and improve ostial drainage by causing vasoconstriction
  • antihistamines and intranasal steroids to inhibit inflammation
  • appropriate doses of analgesics and antipyretics as needed

It should be recognized that some studies of these proteolytic enzymes, alpha-adrenergic agonists, mucolytic agents, intranasal corticosteroids, and antihistamines have been carried out in conjunction with antibiotics, have included patients with chronic sinusitis, and have shown varying efficacy.

In patients with a higher risk of bacterial sinusitis with two or more of the above factors present, assess the severity of the patient's symptoms. Unfortunately, there is no validated tool to assess symptoms quantitatively in patients with acute sinusitis. However, if symptoms are severe, consider immediate short-course antibiotic therapy. If symptoms are less severe, consider antibiotic therapy if there has been no improvement after seven to 10 days of symptomatic therapy.

When using antibiotic therapy, use amoxicillin or amoxicillin-clavulanate as a first-line agent. In penicillin-allergic patients, consider doxycycline or trimethoprim-sulfamethoxazole in adults and doxycycline in older children (but not in younger children). There are few data on the optimal duration of therapy. Most trials have been carried out for seven to 14 days, but there is no firm evidence that such long courses are needed to treat acute bacterial sinusitis.

The predominant organisms in patients with acute bacterial sinusitis since the 1970s are S. pneumoniae and H. influenzae. Studies done in the 1990s showed some contribution from M. catarrhalis some H. influenzae, producing beta-lactamases and making them resistant to penicillin and amoxicillin. These latter two organisms are sensitive to doxycycline.

Although randomized trials have demonstrated the effectiveness of antibiotics in treating acute sinusitis, there is a high spontaneous cure rate in patients given placebo, suggesting that some of the patients may have had viral sinusitis. Decision analysis suggests that initial empirical antibiotic therapy is most cost-effective when the expected prevalence of bacterial sinusitis is high.

Despite concerns about development of bacterial resistance, there are few data to suggest that newer, more costly broader-spectrum antibiotics are more effective in adults than the older, narrow-spectrum agents recommended above. It is worth noting, however, that pneumococcal resistance rates for trimethoprim-sulfamethoxazole may be as high as 18% to 20%, and this drug is not recommended in children.

Minor adverse reactions, mainly gastrointestinal, occur in 10% to 20% of patients taking amoxicillin, folate inhibitors and doxycycline, but the withdrawal rate in randomized trials of these agents is about 4% to 6%. In most cases, side effects disappear when the drugs are discontinued.


Symptoms of uncomplicated acute sinusitis usually resolve within four weeks, and routine office visits may only increase the cost of management of this generally benign condition without meaningful clinical gains. However, re-evaluate the patient when symptoms persist or new symptoms develop. Failure to improve or new and worsening symptoms may suggest complications, such as spread of infection beyond the sinuses. In such cases, in addition to careful physical examination, imaging studies and appropriate consultation may be necessary.

This information comes from the PIER module "Acute Sinusitis."

The information included herein should never be used as a substitute for clinical judgment and does not represent an official position of the ACP.


Conditions predisposing to sinusitis


  • Viral upper respiratory infections
  • Allergic rhinitis
  • Deviated nasal septum
  • Nasal polyps
  • Foreign bodies
  • Swimming and diving
  • Smoking


  • Immune deficiency
  • Cystic fibrosis
  • Dysmotile cilia syndrome


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