Most sinus infections don't require antibiotics

The vast majority of sinus infections are caused by viruses and should not be treated with antibiotics, suggest new guidelines released by the Infectious Diseases Society of America (IDSA).

Nearly one in seven people are diagnosed with a sinus infection each year. Although sinus infections are the fifth leading reason for antibiotic prescriptions, 90 to 98 percent of cases are caused by viruses, which are not affected by antibiotics. Used inappropriately, antibiotics foster the development of drug-resistant superbugs.

"There is no simple test that will easily and quickly determine whether a sinus infection is viral or bacterial, so many physicians prescribe antibiotics 'just in case,'" said Anthony W. Chow, MD, chair of the guidelines panel and professor emeritus of infectious diseases at the University of British Columbia, Vancouver. "However, if the infection turns out to be viral – as most are – the antibiotics won't help and in fact can cause harm by increasing antibiotic resistance, exposing patients to drug side effects unnecessarily and adding cost."

The guidelines – the first developed by IDSA on this topic – provide specific characteristics of the illness to help doctors distinguish between viral and bacterial sinus infections.

A sinus infection, called acute rhinosinusitis, is inflammation of the nasal and sinus passages that can cause uncomfortable pressure on either side of the nose and last for weeks. Most sinus infections develop during or after a cold or other upper respiratory infection, but other factors such as allergens and environmental irritants may play a role.

The guidelines recommend treating bacterial sinus infections with amoxicillin-clavulanate versus the current standard of care, amoxicillin. The addition of clavulanate helps to overcome antibiotic resistance by inhibiting an enzyme that breaks down the antibiotic. The guidelines also recommend against using other commonly used antibiotics, including azithromycin, clarithromycin and trimethoprim-sulfamethoxazole, due to increasing drug resistance.

The recommendation to use amoxicillin-clavulanate instead of amoxicillin is a major shift from older guidelines developed by other organizations. Dr. Chow notes that this recommendation was made due to increases in antibiotic resistance as well as the common use of pneumococcal vaccines, which have changed the pattern of bacteria that cause sinus infections.

Acute rhinosinusitis Acute rhinosinusitis is characterized by inflammation of the nasal mucosa and paranasal sinuses for less than 4 weeks. Although clinicians frequently prescribe antibiotics for rhinosinusitis, it is almost always viral in origin with less than 2% of the cases stemming from bacteria. Bacterial rhinosinusitis typically results from a secondary infection arising from sinus ostia obstruction and impaired mucous drainage with the most common organisms being , , and in decreasing order of prevalence.