THURSDAY, Dec. 29 (HealthDay News) -- Sinusitis is one of the most diagnosed diseases in the United States, affecting approximately 16 percent of adults, and is responsible for nearly $5.8 billion in health-care costs annually.

Updated recommendations for the diagnosis and management of sinusitis have just been released by the American Academy of Allergy, Asthma & Immunology.

The updated practice guidelines include these sinusitis classifications:

• Acute sinusitis. Symptoms last for less than four weeks and include the following: persistent symptoms of an upper respiratory tract infection, purulent rhinorrhea, postnasal drainage, anosmia, nasal congestion, facial pain, headache, fever, cough and purulent discharge.
• Subacute sinusitis: symptoms from four to eight weeks.
• Chronic sinusitis: symptoms for eight weeks or longer of varying severity consisting of the same symptoms as seen in acute sinusitis.
• Recurrent sinusitis: three or more episodes of acute sinusitis a year.

Diagnosis of sinusitis is based on a combination of clinical history, physical examination, imaging studies, and/or laboratory tests. The updated guidelines recommend:

• Diagnosis of acute sinusitis should be primarily based on the history and physical examination of the patient. Imaging techniques such as radiographs or CT scans are not necessary.
• Antibiotics should be withheld for 10 to 14 days, unless the patient develops severe symptoms such as fever, facial pain or tenderness, or swelling around the eye.
• Antibiotics are the primary therapy for sinusitis. However, with increasing resistance to penicillin being reported, it may be necessary to use alternative antibiotics.
• Referral to an allergist/immunologist is needed, particularly for people with chronic or recurrent sinusitis associated with certain conditions and for patients who've had prior surgery but still experience sinusitis.
• Surgery should be considered only after medical therapy has failed.

The guidelines appear in the December issue of the Journal of Allergy & Clinical Immunology.